From a08dfecc57eefcbdff0127b4615ac797ea008d1a Mon Sep 17 00:00:00 2001
From: kt <kt@katbyte.me>
Date: Wed, 7 Oct 2026 10:47:51 -0700
Subject: [PATCH 1/3] changelog and readme

---
 CHANGELOG.md                                  |   5 +
 README.md                                     |  19 +++
 cli/pr-ast.go                                 |  37 ++----
 cli/pr.go                                     |  38 ++----
 integration/integration_azurerm_test.go       | 123 ++++++++++++++++++
 .../batch/actions/batch_pool_resize/action.go |  19 +++
 .../actions/batch_pool_resize/action_test.go  |  25 ++++
 .../internal/services/batch/parse/pool.go     |  24 ++++
 .../internal/services/batch/registration.go   |  37 ++++++
 .../resources/batch_account/data_source.go    |  22 ++++
 .../batch_account/data_source_test.go         |  25 ++++
 .../batch/resources/batch_account/r_schema.go |  24 ++++
 .../batch/resources/batch_account/r_update.go |  20 +++
 .../batch/resources/batch_account/resource.go |  26 ++++
 .../resources/batch_account/resource_test.go  |  36 +++++
 .../batch/resources/batch_pool/r_read.go      |  22 ++++
 .../batch/resources/batch_pool/r_schema.go    |  20 +++
 .../batch/resources/batch_pool/resource.go    |  16 +++
 .../resources/batch_pool/resource_test.go     |  25 ++++
 .../services/batch/validate/account_name.go   |  22 ++++
 .../services/batch/validate/pool_id.go        |  23 ++++
 .../batch/2024-07-01/pool/id_pool.go          |  23 ++++
 lib/provider/file-types.go                    |   5 +-
 lib/provider/file.go                          |  24 ++++
 lib/provider/resource_folder.go               |  42 ++++++
 lib/provider/resource_folder_test.go          |  76 +++++++++++
 26 files changed, 722 insertions(+), 56 deletions(-)
 create mode 100644 integration/testdata/azurerm/internal/services/batch/actions/batch_pool_resize/action.go
 create mode 100644 integration/testdata/azurerm/internal/services/batch/actions/batch_pool_resize/action_test.go
 create mode 100644 integration/testdata/azurerm/internal/services/batch/parse/pool.go
 create mode 100644 integration/testdata/azurerm/internal/services/batch/registration.go
 create mode 100644 integration/testdata/azurerm/internal/services/batch/resources/batch_account/data_source.go
 create mode 100644 integration/testdata/azurerm/internal/services/batch/resources/batch_account/data_source_test.go
 create mode 100644 integration/testdata/azurerm/internal/services/batch/resources/batch_account/r_schema.go
 create mode 100644 integration/testdata/azurerm/internal/services/batch/resources/batch_account/r_update.go
 create mode 100644 integration/testdata/azurerm/internal/services/batch/resources/batch_account/resource.go
 create mode 100644 integration/testdata/azurerm/internal/services/batch/resources/batch_account/resource_test.go
 create mode 100644 integration/testdata/azurerm/internal/services/batch/resources/batch_pool/r_read.go
 create mode 100644 integration/testdata/azurerm/internal/services/batch/resources/batch_pool/r_schema.go
 create mode 100644 integration/testdata/azurerm/internal/services/batch/resources/batch_pool/resource.go
 create mode 100644 integration/testdata/azurerm/internal/services/batch/resources/batch_pool/resource_test.go
 create mode 100644 integration/testdata/azurerm/internal/services/batch/validate/account_name.go
 create mode 100644 integration/testdata/azurerm/internal/services/batch/validate/pool_id.go
 create mode 100644 integration/testdata/azurerm/vendor/github.com/hashicorp/go-azure-sdk/resource-manager/batch/2024-07-01/pool/id_pool.go
 create mode 100644 lib/provider/resource_folder.go
 create mode 100644 lib/provider/resource_folder_test.go

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d9c5e45..36aaaca 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+## Unreleased
+
+- support the azurerm resource-per-folder layout (`internal/services/batch/resources/batch_account/{resource,r_create,data_source}.go`, and `actions/` alongside `resources/`): a change to any file in a resource folder now discovers the tests in that folder, and import tracing from helper packages follows into resource folders
+- API discovery lists directories at the PR's merge commit rather than the default branch, so tests are found in directories the PR adds or moves files into
+
 ## v1.3.5 (2026-10-20)
 
 - build with Go 1.26.9 for its fixes to the standard library's HTTP and TLS code, mostly ways a misbehaving connection could stall or crash the program (CVE-2026-78667, CVE-2026-78669, CVE-2026-97031 and others); govulncheck finds tctest reaches several of them, and the binary now scans clean ([#152](https://github.com/katbyte/tctest/pull/152))
diff --git a/README.md b/README.md
index 8013ae7..b57ef2d 100755
--- a/README.md
+++ b/README.md
@@ -337,6 +337,25 @@ When no test regex is provided, `tctest` automatically discovers tests by:
 
 Files in `/client/`, `/parse/`, `/validate/` subdirectories and `registration.go`/`resourceids.go` are automatically skipped. Deleted files are also excluded.
 
+### Resource Folders
+
+The azurerm resource-per-folder layout gives each resource (or action) its own package under `resources/` (or `actions/`) in the service, and drops the resource name from the file names:
+
+```
+internal/services/batch/resources/batch_account/
+    resource.go  r_create.go  r_schema.go  data_source.go  list.go
+    resource_test.go  resource_identity_gen_test.go  data_source_test.go  list_test.go
+internal/services/managedredis/actions/managed_redis_flush_databases/
+    action.go  action_test.go
+```
+
+Any file directly inside `<service>/resources/<folder>/` or `<service>/actions/<folder>/` belongs to that folder's resource. Since the file names no longer say which resource they belong to, the folder does:
+
+- a change to `data_source.go`, `list.go`, `action.go` or `ephemeral.go` discovers that file's own tests (`data_source_test.go`, ...)
+- a change to any other file in the folder (`resource.go`, `r_*.go`, shared models) discovers every test file in the folder
+
+Helper packages such as `parse/` and `validate/` are unaffected, and both layouts can be mixed within a service. The service (and so the build triggered) is still the first directory: `batch`.
+
 ### Test Output
 
 Discovered tests are grouped by service and displayed with padded service names for alignment:
diff --git a/cli/pr-ast.go b/cli/pr-ast.go
index 3c0525d..f01ed66 100644
--- a/cli/pr-ast.go
+++ b/cli/pr-ast.go
@@ -176,26 +176,7 @@ func (dc *AstDiscoveryContext) findLocalTestFiles(relativeDir string, resourcePr
 			continue
 		}
 
-		matched := false
-		for _, prefix := range resourcePrefixes {
-			if !strings.HasPrefix(pf.BaseName, prefix) {
-				continue
-			}
-			remainder := pf.BaseName[len(prefix):]
-
-			for _, re := range dc.Config.AccTestFileSuffixRegexes {
-				if re.MatchString(remainder) {
-					matched = true
-					break
-				}
-			}
-
-			if matched {
-				break
-			}
-		}
-
-		if matched {
+		if pf.IsTestFor(resourcePrefixes, dc.Config.AccTestFileSuffixRegexes) {
 			testFiles = append(testFiles, pf)
 		}
 	}
@@ -329,7 +310,7 @@ func (dc *AstDiscoveryContext) traceImportsToResourceFiles(helperFiles []provide
 
 				// if we have no symbol info, fall back to package-level matching
 				if len(symbols) == 0 {
-					if dc.Config.FileRegEx.MatchString(relPath) {
+					if dc.isResourceFile(relPath) {
 						dir := filepath.ToSlash(filepath.Dir(relPath))
 						result[dir] = append(result[dir], relPath)
 						clog.Log.Debugf("    traced: %s imports %s (depth %d, package-level)", relPath, pkgPath, depth+1)
@@ -369,7 +350,7 @@ func (dc *AstDiscoveryContext) traceImportsToResourceFiles(helperFiles []provide
 				}
 
 				// this file uses a changed symbol
-				if dc.Config.FileRegEx.MatchString(relPath) {
+				if dc.isResourceFile(relPath) {
 					// it's a resource file — add to results
 					dir := filepath.ToSlash(filepath.Dir(relPath))
 					result[dir] = append(result[dir], relPath)
@@ -397,6 +378,12 @@ func (dc *AstDiscoveryContext) traceImportsToResourceFiles(helperFiles []provide
 	return result
 }
 
+// isResourceFile returns true if the repo-relative path is a file whose sibling tests should run when it is affected:
+// it matches the fileregex (resource at the service root), or it lives in a resource folder.
+func (dc *AstDiscoveryContext) isResourceFile(relPath string) bool {
+	return dc.Config.FileRegEx.MatchString(relPath) || provider.InResourceFolder(relPath)
+}
+
 func (dc *AstDiscoveryContext) SortedTestFiles() []*provider.File {
 	files := make([]*provider.File, 0, len(dc.TestFiles))
 	for _, pf := range dc.TestFiles {
@@ -512,7 +499,7 @@ func (dc *AstDiscoveryContext) TraceHelperFiles(helperFiles []provider.File) {
 		if entries, err := os.ReadDir(filepath.Join(dc.RepoPath, dir)); err == nil {
 			for _, entry := range entries {
 				if !entry.IsDir() && strings.HasSuffix(entry.Name(), ".go") {
-					if dc.Config.FileRegEx.MatchString(filepath.ToSlash(filepath.Join(dir, entry.Name()))) {
+					if dc.isResourceFile(filepath.ToSlash(filepath.Join(dir, entry.Name()))) {
 						isSamePkg = true
 						break
 					}
@@ -560,7 +547,7 @@ func (dc *AstDiscoveryContext) TraceHelperFiles(helperFiles []provider.File) {
 				continue
 			}
 			relPath := filepath.ToSlash(filepath.Join(dir, entry.Name()))
-			if !dc.Config.FileRegEx.MatchString(relPath) {
+			if !dc.isResourceFile(relPath) {
 				continue
 			}
 
@@ -742,7 +729,7 @@ func (dc *AstDiscoveryContext) TraceVendorFiles(vendorFiles []provider.File) {
 			}
 			relPath = filepath.ToSlash(relPath)
 
-			if !dc.Config.FileRegEx.MatchString(relPath) {
+			if !dc.isResourceFile(relPath) {
 				return nil
 			}
 
diff --git a/cli/pr.go b/cli/pr.go
index e6140be..3ad991c 100755
--- a/cli/pr.go
+++ b/cli/pr.go
@@ -94,7 +94,7 @@ func (ghr GithubRepo) PrTestsFromAPI(pri int, cfg DiscoveryConfig) (map[string][
 	}
 
 	clog.Log.Tracef("listing files...")
-	filesFiltered, err := ghr.GetPullRequestTestFiles(pri, cfg)
+	filesFiltered, err := ghr.GetPullRequestTestFiles(pri, pr.GetMergeCommitSHA(), cfg)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get PR files for %s/%s/pull/%d: %w", ghr.Owner, ghr.Name, pri, err)
 	}
@@ -192,7 +192,9 @@ func (f *FlagData) CheckPrCanBuild(number int) error {
 
 // GetPullRequestTestFiles fetches all changed files in a PR and determines the related test files.
 // It classifies files based on the DiscoveryConfig and lists contents of directories containing changed resources to find related tests.
-func (ghr GithubRepo) GetPullRequestTestFiles(pri int, cfg DiscoveryConfig) ([]provider.File, error) {
+// Directories are listed at ref (the PR's merge commit, the same commit file contents are downloaded from) so directories
+// the PR adds or moves files into are seen; an empty ref lists the default branch.
+func (ghr GithubRepo) GetPullRequestTestFiles(pri int, ref string, cfg DiscoveryConfig) ([]provider.File, error) {
 	// track resource files that need sibling test file discovery
 	// key: directory path, value: list of resource prefixes (e.g. "foo")
 	resourcePrefixesByPackage := map[string][]string{}
@@ -280,13 +282,12 @@ func (ghr GithubRepo) GetPullRequestTestFiles(pri int, cfg DiscoveryConfig) ([]p
 		client, ctx := ghr.NewClient()
 		for dir, prefixes := range resourcePrefixesByPackage {
 			clog.Log.Debugf("  listing directory %s for related test files...", dir)
-			_, dirContents, _, err := client.Repositories.GetContents(ctx, ghr.Owner, ghr.Name, dir, nil)
+			_, dirContents, _, err := client.Repositories.GetContents(ctx, ghr.Owner, ghr.Name, dir, &github.RepositoryContentGetOptions{Ref: ref})
 			if err != nil {
-				// a directory new in this PR won't exist on the default branch; anything else
-				// would silently drop derived sibling test files
+				// a missing directory is not fatal; anything else would silently drop derived sibling test files
 				var ghErr *github.ErrorResponse
 				if errors.As(err, &ghErr) && ghErr.Response != nil && ghErr.Response.StatusCode == http.StatusNotFound {
-					clog.Log.Debugf("  directory %s not found (new in this PR?), skipping sibling test discovery", dir)
+					clog.Log.Debugf("  directory %s not found, skipping sibling test discovery", dir)
 					continue
 				}
 				return nil, fmt.Errorf("failed to list directory %s for related test files: %w", dir, err)
@@ -294,30 +295,7 @@ func (ghr GithubRepo) GetPullRequestTestFiles(pri int, cfg DiscoveryConfig) ([]p
 
 			for _, entry := range dirContents {
 				pf := provider.NewFile(path.Join(dir, entry.GetName()))
-				if pf.Type != provider.FileTypeTest {
-					continue
-				}
-
-				shouldInclude := false
-				for _, resource := range prefixes {
-					if !strings.HasPrefix(pf.BaseName, resource) {
-						continue
-					}
-
-					remainder := pf.BaseName[len(resource):]
-					for _, testSuffix := range cfg.AccTestFileSuffixRegexes {
-						if testSuffix.MatchString(remainder) {
-							shouldInclude = true
-							break
-						}
-					}
-
-					if shouldInclude {
-						break
-					}
-				}
-
-				if !shouldInclude {
+				if pf.Type != provider.FileTypeTest || !pf.IsTestFor(prefixes, cfg.AccTestFileSuffixRegexes) {
 					continue
 				}
 
diff --git a/integration/integration_azurerm_test.go b/integration/integration_azurerm_test.go
index f3b4e35..2898eb4 100644
--- a/integration/integration_azurerm_test.go
+++ b/integration/integration_azurerm_test.go
@@ -46,6 +46,21 @@ var azurermPRs = []prDef{
 	{1021, "open", "dns bug fix", []changedFile{
 		{"internal/services/dns/dns_a_record_resource.go", "modified", ""},
 	}},
+	{1030, "open", "resource folder: part of the resource changed", []changedFile{
+		{"internal/services/batch/resources/batch_account/r_update.go", "modified", ""},
+	}},
+	{1031, "open", "resource folder: data source changed", []changedFile{
+		{"internal/services/batch/resources/batch_account/data_source.go", "modified", ""},
+	}},
+	{1032, "open", "resource folder: helper package beside the folders changed", []changedFile{
+		{"internal/services/batch/validate/account_name.go", "modified", ""},
+	}},
+	{1033, "open", "action folder changed", []changedFile{
+		{"internal/services/batch/actions/batch_pool_resize/action.go", "modified", ""},
+	}},
+	{1034, "open", "resource folder: test file changed", []changedFile{
+		{"internal/services/batch/resources/batch_account/resource_test.go", "modified", "@@ -26,3 +26,3 @@"},
+	}},
 }
 
 // azurermASTPRs are served for the AST-mode tests; the merge refs for these
@@ -90,6 +105,27 @@ var azurermASTPRs = []prDef{
 	{2012, "open", "conflicted pr", []changedFile{
 		{"internal/services/postgres/postgresql_flexible_server_resource_test.go", "modified", ""},
 	}},
+	{2013, "open", "resource folder: part of the resource changed", []changedFile{
+		{"internal/services/batch/resources/batch_account/r_update.go", "modified", ""},
+	}},
+	{2014, "open", "resource folder: data source changed", []changedFile{
+		{"internal/services/batch/resources/batch_account/data_source.go", "modified", ""},
+	}},
+	{2015, "open", "resource folder: helper package beside the folders changed", []changedFile{
+		{"internal/services/batch/validate/account_name.go", "modified", ""},
+	}},
+	{2016, "open", "action folder changed", []changedFile{
+		{"internal/services/batch/actions/batch_pool_resize/action.go", "modified", ""},
+	}},
+	{2017, "open", "resource folder: test file changed", []changedFile{
+		{"internal/services/batch/resources/batch_account/resource_test.go", "modified", "@@ -26,3 +26,3 @@"},
+	}},
+	{2018, "open", "resource folder: two-level helper chain changed", []changedFile{
+		{"internal/services/batch/parse/pool.go", "modified", ""},
+	}},
+	{2019, "open", "resource folder: vendored dependency changed", []changedFile{
+		{"vendor/github.com/hashicorp/go-azure-sdk/resource-manager/batch/2024-07-01/pool/id_pool.go", "modified", ""},
+	}},
 }
 
 // conflictedPRs marks the PR numbers the mock serves with mergeable=false
@@ -233,11 +269,50 @@ func TestAPIDiscoveryAzureRM(t *testing.T) {
 			name: "--service all triggers every service directly",
 			args: []string{"pr", "1001", "--service", "all", "--all"},
 			want: []trigger{
+				{"TF_E2E_BATCH", "refs/pull/1001/merge", "TestAcc"},
 				{"TF_E2E_COSMOS", "refs/pull/1001/merge", "TestAcc"},
 				{"TF_E2E_DNS", "refs/pull/1001/merge", "TestAcc"},
 				{"TF_E2E_POSTGRES", "refs/pull/1001/merge", "TestAcc"},
 			},
 		},
+		{
+			// resource-per-folder layout: files drop the resource name (batch/resources/batch_account/r_update.go), so the
+			// folder rather than a filename prefix ties them to their tests — and the pool folder next door is left alone
+			name: "resource folder file runs every test in its folder",
+			args: []string{"pr", "1030"},
+			want: []trigger{{"TF_E2E_BATCH", "refs/pull/1030/merge", "(TestAccBatchAccount|TestAccBatchAccountDataSource)"}},
+		},
+		{
+			name: "resource folder data source runs only the data source tests",
+			args: []string{"pr", "1031"},
+			want: []trigger{{"TF_E2E_BATCH", "refs/pull/1031/merge", "(TestAccBatchAccountDataSource)"}},
+		},
+		{
+			name:     "helper package beside resource folders is not mistaken for one",
+			args:     []string{"pr", "1032"},
+			want:     nil,
+			wantExit: 1,
+		},
+		{
+			name: "action folder runs the action tests",
+			args: []string{"pr", "1033"},
+			want: []trigger{{"TF_E2E_BATCH", "refs/pull/1033/merge", "(TestAccBatchPoolResizeAction)"}},
+		},
+		{
+			name: "resource folder test file runs its tests",
+			args: []string{"pr", "1034"},
+			want: []trigger{{"TF_E2E_BATCH", "refs/pull/1034/merge", "(TestAccBatchAccount)"}},
+		},
+		{
+			name: "individual flag narrows resource folder test file to the modified test functions",
+			args: []string{"pr", "1034", "-i"},
+			want: []trigger{{"TF_E2E_BATCH", "refs/pull/1034/merge", "(TestAccBatchAccount_update)"}},
+		},
+		{
+			name: "individual flag lists every test in the resource folder by full name",
+			args: []string{"pr", "1030", "-i"},
+			want: []trigger{{"TF_E2E_BATCH", "refs/pull/1030/merge", "(TestAccBatchAccountDataSource_basic|TestAccBatchAccount_basic|TestAccBatchAccount_update)"}},
+		},
 	}
 
 	for _, tt := range cases {
@@ -374,6 +449,54 @@ func TestASTDiscoveryAzureRM(t *testing.T) {
 			want:     nil,
 			wantExit: 1,
 		},
+		{
+			name: "resource folder file runs every test in its folder",
+			args: []string{"pr", "2013"},
+			want: []trigger{{"TF_E2E_BATCH", "refs/pull/2013/merge", "(TestAccBatchAccount|TestAccBatchAccountDataSource)"}},
+		},
+		{
+			name: "resource folder data source runs only the data source tests",
+			args: []string{"pr", "2014"},
+			want: []trigger{{"TF_E2E_BATCH", "refs/pull/2014/merge", "(TestAccBatchAccountDataSource)"}},
+		},
+		{
+			// validate.AccountName is only used by batch_account/r_schema.go, so the pool folder is left alone
+			name: "cross-package helper traces into the resource folder using it",
+			args: []string{"pr", "2015"},
+			want: []trigger{{"TF_E2E_BATCH", "refs/pull/2015/merge", "(TestAccBatchAccount|TestAccBatchAccountDataSource)"}},
+		},
+		{
+			name: "action folder runs the action tests",
+			args: []string{"pr", "2016"},
+			want: []trigger{{"TF_E2E_BATCH", "refs/pull/2016/merge", "(TestAccBatchPoolResizeAction)"}},
+		},
+		{
+			name: "resource folder test file runs its tests",
+			args: []string{"pr", "2017"},
+			want: []trigger{{"TF_E2E_BATCH", "refs/pull/2017/merge", "(TestAccBatchAccount)"}},
+		},
+		{
+			name: "individual flag narrows resource folder test file to the modified test functions",
+			args: []string{"pr", "2017", "-i"},
+			want: []trigger{{"TF_E2E_BATCH", "refs/pull/2017/merge", "(TestAccBatchAccount_update)"}},
+		},
+		{
+			name: "individual flag lists every test in the resource folder by full name",
+			args: []string{"pr", "2013", "-i"},
+			want: []trigger{{"TF_E2E_BATCH", "refs/pull/2013/merge", "(TestAccBatchAccountDataSource_basic|TestAccBatchAccount_basic|TestAccBatchAccount_update)"}},
+		},
+		{
+			// parse.PoolID is used by validate.PoolID, which only batch_pool/r_schema.go uses; the account folder
+			// imports the same validate package for a different function — it must NOT be selected
+			name: "two-level helper chain traces into the resource folder using it",
+			args: []string{"pr", "2018"},
+			want: []trigger{{"TF_E2E_BATCH", "refs/pull/2018/merge", "(TestAccBatchPool)"}},
+		},
+		{
+			name: "vendored dependency change traces into the resource folder importing it",
+			args: []string{"pr", "2019"},
+			want: []trigger{{"TF_E2E_BATCH", "refs/pull/2019/merge", "(TestAccBatchPool)"}},
+		},
 	}
 
 	for _, tt := range cases {
diff --git a/integration/testdata/azurerm/internal/services/batch/actions/batch_pool_resize/action.go b/integration/testdata/azurerm/internal/services/batch/actions/batch_pool_resize/action.go
new file mode 100644
index 0000000..53ae654
--- /dev/null
+++ b/integration/testdata/azurerm/internal/services/batch/actions/batch_pool_resize/action.go
@@ -0,0 +1,19 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package batch_pool_resize
+
+import (
+	"github.com/hashicorp/terraform-plugin-framework/action"
+	"github.com/hashicorp/terraform-provider-azurerm/internal/sdk"
+)
+
+type BatchPoolResizeAction struct {
+	sdk.ActionMetadata
+}
+
+var _ sdk.Action = &BatchPoolResizeAction{}
+
+func Action() action.Action {
+	return &BatchPoolResizeAction{}
+}
diff --git a/integration/testdata/azurerm/internal/services/batch/actions/batch_pool_resize/action_test.go b/integration/testdata/azurerm/internal/services/batch/actions/batch_pool_resize/action_test.go
new file mode 100644
index 0000000..9ce58b8
--- /dev/null
+++ b/integration/testdata/azurerm/internal/services/batch/actions/batch_pool_resize/action_test.go
@@ -0,0 +1,25 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package batch_pool_resize_test
+
+import (
+	"testing"
+
+	"github.com/hashicorp/terraform-provider-azurerm/internal/acceptance"
+)
+
+type BatchPoolResizeAction struct{}
+
+func TestAccBatchPoolResizeAction_basic(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_batch_pool_resize", "test")
+	a := BatchPoolResizeAction{}
+
+	data.ResourceTest(t, a, []acceptance.TestStep{
+		{Config: a.basic(data)},
+	})
+}
+
+func (BatchPoolResizeAction) basic(data acceptance.TestData) string {
+	return ""
+}
diff --git a/integration/testdata/azurerm/internal/services/batch/parse/pool.go b/integration/testdata/azurerm/internal/services/batch/parse/pool.go
new file mode 100644
index 0000000..4cb48d8
--- /dev/null
+++ b/integration/testdata/azurerm/internal/services/batch/parse/pool.go
@@ -0,0 +1,24 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package parse
+
+import (
+	"fmt"
+	"strings"
+)
+
+type PoolId struct {
+	AccountName string
+	Name        string
+}
+
+// PoolID parses "<account>/<pool>" into a PoolId struct
+func PoolID(input string) (*PoolId, error) {
+	account, name, found := strings.Cut(input, "/")
+	if !found {
+		return nil, fmt.Errorf("parsing %q as a Pool ID", input)
+	}
+
+	return &PoolId{AccountName: account, Name: name}, nil
+}
diff --git a/integration/testdata/azurerm/internal/services/batch/registration.go b/integration/testdata/azurerm/internal/services/batch/registration.go
new file mode 100644
index 0000000..28bc304
--- /dev/null
+++ b/integration/testdata/azurerm/internal/services/batch/registration.go
@@ -0,0 +1,37 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package batch
+
+import (
+	"github.com/hashicorp/terraform-plugin-framework/action"
+	"github.com/hashicorp/terraform-provider-azurerm/internal/sdk"
+	"github.com/hashicorp/terraform-provider-azurerm/internal/services/batch/actions/batch_pool_resize"
+	"github.com/hashicorp/terraform-provider-azurerm/internal/services/batch/resources/batch_account"
+	"github.com/hashicorp/terraform-provider-azurerm/internal/services/batch/resources/batch_pool"
+)
+
+type Registration struct{}
+
+func (r Registration) Name() string {
+	return "Batch"
+}
+
+func (r Registration) Resources() []sdk.Resource {
+	return []sdk.Resource{
+		batch_account.BatchAccountResource{},
+		batch_pool.BatchPoolResource{},
+	}
+}
+
+func (r Registration) DataSources() []sdk.DataSource {
+	return []sdk.DataSource{
+		batch_account.BatchAccountDataSource{},
+	}
+}
+
+func (r Registration) Actions() []func() action.Action {
+	return []func() action.Action{
+		batch_pool_resize.Action,
+	}
+}
diff --git a/integration/testdata/azurerm/internal/services/batch/resources/batch_account/data_source.go b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/data_source.go
new file mode 100644
index 0000000..e7221ef
--- /dev/null
+++ b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/data_source.go
@@ -0,0 +1,22 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package batch_account
+
+import (
+	"time"
+
+	"github.com/hashicorp/terraform-provider-azurerm/internal/sdk"
+)
+
+type BatchAccountDataSource struct{}
+
+var _ sdk.DataSource = BatchAccountDataSource{}
+
+func (r BatchAccountDataSource) ResourceType() string {
+	return "azurerm_batch_account"
+}
+
+func (r BatchAccountDataSource) Read() sdk.ResourceFunc {
+	return sdk.ResourceFunc{Timeout: 5 * time.Minute}
+}
diff --git a/integration/testdata/azurerm/internal/services/batch/resources/batch_account/data_source_test.go b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/data_source_test.go
new file mode 100644
index 0000000..efa3258
--- /dev/null
+++ b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/data_source_test.go
@@ -0,0 +1,25 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package batch_account_test
+
+import (
+	"testing"
+
+	"github.com/hashicorp/terraform-provider-azurerm/internal/acceptance"
+)
+
+type BatchAccountDataSource struct{}
+
+func TestAccBatchAccountDataSource_basic(t *testing.T) {
+	data := acceptance.BuildTestData(t, "data.azurerm_batch_account", "test")
+	r := BatchAccountDataSource{}
+
+	data.DataSourceTest(t, []acceptance.TestStep{
+		{Config: r.basic(data)},
+	})
+}
+
+func (BatchAccountDataSource) basic(data acceptance.TestData) string {
+	return ""
+}
diff --git a/integration/testdata/azurerm/internal/services/batch/resources/batch_account/r_schema.go b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/r_schema.go
new file mode 100644
index 0000000..19c4022
--- /dev/null
+++ b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/r_schema.go
@@ -0,0 +1,24 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package batch_account
+
+import (
+	"github.com/hashicorp/terraform-provider-azurerm/internal/services/batch/validate"
+	"github.com/hashicorp/terraform-provider-azurerm/internal/tf/pluginsdk"
+)
+
+type BatchAccountModel struct {
+	Name string `tfschema:"name"`
+}
+
+func (r BatchAccountResource) Arguments() map[string]*pluginsdk.Schema {
+	return map[string]*pluginsdk.Schema{
+		"name": {
+			Type:         pluginsdk.TypeString,
+			Required:     true,
+			ForceNew:     true,
+			ValidateFunc: validate.AccountName,
+		},
+	}
+}
diff --git a/integration/testdata/azurerm/internal/services/batch/resources/batch_account/r_update.go b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/r_update.go
new file mode 100644
index 0000000..6caf834
--- /dev/null
+++ b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/r_update.go
@@ -0,0 +1,20 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package batch_account
+
+import (
+	"context"
+	"time"
+
+	"github.com/hashicorp/terraform-provider-azurerm/internal/sdk"
+)
+
+func (r BatchAccountResource) Update() sdk.ResourceFunc {
+	return sdk.ResourceFunc{
+		Timeout: 30 * time.Minute,
+		Func: func(ctx context.Context, metadata sdk.ResourceMetaData) error {
+			return nil
+		},
+	}
+}
diff --git a/integration/testdata/azurerm/internal/services/batch/resources/batch_account/resource.go b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/resource.go
new file mode 100644
index 0000000..4212984
--- /dev/null
+++ b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/resource.go
@@ -0,0 +1,26 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package batch_account
+
+import (
+	"time"
+
+	"github.com/hashicorp/terraform-provider-azurerm/internal/sdk"
+)
+
+type BatchAccountResource struct{}
+
+var _ sdk.ResourceWithUpdate = BatchAccountResource{}
+
+func (r BatchAccountResource) ResourceType() string {
+	return "azurerm_batch_account"
+}
+
+func (r BatchAccountResource) ModelObject() interface{} {
+	return &BatchAccountModel{}
+}
+
+func (r BatchAccountResource) Read() sdk.ResourceFunc {
+	return sdk.ResourceFunc{Timeout: 5 * time.Minute}
+}
diff --git a/integration/testdata/azurerm/internal/services/batch/resources/batch_account/resource_test.go b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/resource_test.go
new file mode 100644
index 0000000..ad3bf99
--- /dev/null
+++ b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/resource_test.go
@@ -0,0 +1,36 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package batch_account_test
+
+import (
+	"testing"
+
+	"github.com/hashicorp/terraform-provider-azurerm/internal/acceptance"
+)
+
+type BatchAccountResource struct{}
+
+func TestAccBatchAccount_basic(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_batch_account", "test")
+	r := BatchAccountResource{}
+
+	data.ResourceTest(t, r, []acceptance.TestStep{
+		{Config: r.basic(data)},
+		data.ImportStep(),
+	})
+}
+
+func TestAccBatchAccount_update(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_batch_account", "test")
+	r := BatchAccountResource{}
+
+	data.ResourceTest(t, r, []acceptance.TestStep{
+		{Config: r.basic(data)},
+		data.ImportStep(),
+	})
+}
+
+func (BatchAccountResource) basic(data acceptance.TestData) string {
+	return ""
+}
diff --git a/integration/testdata/azurerm/internal/services/batch/resources/batch_pool/r_read.go b/integration/testdata/azurerm/internal/services/batch/resources/batch_pool/r_read.go
new file mode 100644
index 0000000..45e6691
--- /dev/null
+++ b/integration/testdata/azurerm/internal/services/batch/resources/batch_pool/r_read.go
@@ -0,0 +1,22 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package batch_pool
+
+import (
+	"context"
+	"time"
+
+	"github.com/hashicorp/go-azure-sdk/resource-manager/batch/2024-07-01/pool"
+	"github.com/hashicorp/terraform-provider-azurerm/internal/sdk"
+)
+
+func (r BatchPoolResource) Read() sdk.ResourceFunc {
+	return sdk.ResourceFunc{
+		Timeout: 5 * time.Minute,
+		Func: func(ctx context.Context, metadata sdk.ResourceMetaData) error {
+			_, err := pool.ParsePoolID(metadata.ResourceData.Id())
+			return err
+		},
+	}
+}
diff --git a/integration/testdata/azurerm/internal/services/batch/resources/batch_pool/r_schema.go b/integration/testdata/azurerm/internal/services/batch/resources/batch_pool/r_schema.go
new file mode 100644
index 0000000..6753b7c
--- /dev/null
+++ b/integration/testdata/azurerm/internal/services/batch/resources/batch_pool/r_schema.go
@@ -0,0 +1,20 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package batch_pool
+
+import (
+	"github.com/hashicorp/terraform-provider-azurerm/internal/services/batch/validate"
+	"github.com/hashicorp/terraform-provider-azurerm/internal/tf/pluginsdk"
+)
+
+func (r BatchPoolResource) Arguments() map[string]*pluginsdk.Schema {
+	return map[string]*pluginsdk.Schema{
+		"pool_id": {
+			Type:         pluginsdk.TypeString,
+			Required:     true,
+			ForceNew:     true,
+			ValidateFunc: validate.PoolID,
+		},
+	}
+}
diff --git a/integration/testdata/azurerm/internal/services/batch/resources/batch_pool/resource.go b/integration/testdata/azurerm/internal/services/batch/resources/batch_pool/resource.go
new file mode 100644
index 0000000..d2312d4
--- /dev/null
+++ b/integration/testdata/azurerm/internal/services/batch/resources/batch_pool/resource.go
@@ -0,0 +1,16 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package batch_pool
+
+import (
+	"github.com/hashicorp/terraform-provider-azurerm/internal/sdk"
+)
+
+type BatchPoolResource struct{}
+
+var _ sdk.Resource = BatchPoolResource{}
+
+func (r BatchPoolResource) ResourceType() string {
+	return "azurerm_batch_pool"
+}
diff --git a/integration/testdata/azurerm/internal/services/batch/resources/batch_pool/resource_test.go b/integration/testdata/azurerm/internal/services/batch/resources/batch_pool/resource_test.go
new file mode 100644
index 0000000..9a396dd
--- /dev/null
+++ b/integration/testdata/azurerm/internal/services/batch/resources/batch_pool/resource_test.go
@@ -0,0 +1,25 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package batch_pool_test
+
+import (
+	"testing"
+
+	"github.com/hashicorp/terraform-provider-azurerm/internal/acceptance"
+)
+
+type BatchPoolResource struct{}
+
+func TestAccBatchPool_basic(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_batch_pool", "test")
+	r := BatchPoolResource{}
+
+	data.ResourceTest(t, r, []acceptance.TestStep{
+		{Config: r.basic(data)},
+	})
+}
+
+func (BatchPoolResource) basic(data acceptance.TestData) string {
+	return ""
+}
diff --git a/integration/testdata/azurerm/internal/services/batch/validate/account_name.go b/integration/testdata/azurerm/internal/services/batch/validate/account_name.go
new file mode 100644
index 0000000..2aacfbb
--- /dev/null
+++ b/integration/testdata/azurerm/internal/services/batch/validate/account_name.go
@@ -0,0 +1,22 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package validate
+
+import (
+	"fmt"
+	"regexp"
+)
+
+func AccountName(i interface{}, k string) (warnings []string, errors []error) {
+	v, ok := i.(string)
+	if !ok {
+		errors = append(errors, fmt.Errorf("expected type of %q to be string", k))
+		return
+	}
+
+	if !regexp.MustCompile("^[a-z0-9]{3,24}$").MatchString(v) {
+		errors = append(errors, fmt.Errorf("%q must be 3 to 24 lowercase letters and numbers", k))
+	}
+	return
+}
diff --git a/integration/testdata/azurerm/internal/services/batch/validate/pool_id.go b/integration/testdata/azurerm/internal/services/batch/validate/pool_id.go
new file mode 100644
index 0000000..5ebaf1d
--- /dev/null
+++ b/integration/testdata/azurerm/internal/services/batch/validate/pool_id.go
@@ -0,0 +1,23 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package validate
+
+import (
+	"fmt"
+
+	"github.com/hashicorp/terraform-provider-azurerm/internal/services/batch/parse"
+)
+
+func PoolID(i interface{}, k string) (warnings []string, errors []error) {
+	v, ok := i.(string)
+	if !ok {
+		errors = append(errors, fmt.Errorf("expected type of %q to be string", k))
+		return
+	}
+
+	if _, err := parse.PoolID(v); err != nil {
+		errors = append(errors, err)
+	}
+	return
+}
diff --git a/integration/testdata/azurerm/vendor/github.com/hashicorp/go-azure-sdk/resource-manager/batch/2024-07-01/pool/id_pool.go b/integration/testdata/azurerm/vendor/github.com/hashicorp/go-azure-sdk/resource-manager/batch/2024-07-01/pool/id_pool.go
new file mode 100644
index 0000000..6efc23c
--- /dev/null
+++ b/integration/testdata/azurerm/vendor/github.com/hashicorp/go-azure-sdk/resource-manager/batch/2024-07-01/pool/id_pool.go
@@ -0,0 +1,23 @@
+// Copyright (c) HashiCorp Inc. All rights reserved.
+// Licensed under the MIT License. See NOTICE.txt in the project root for license information.
+
+package pool
+
+import (
+	"fmt"
+	"strings"
+)
+
+type PoolId struct {
+	BatchAccountName string
+	PoolName         string
+}
+
+func ParsePoolID(input string) (*PoolId, error) {
+	account, name, found := strings.Cut(input, "/pools/")
+	if !found {
+		return nil, fmt.Errorf("parsing %q as a Pool ID", input)
+	}
+
+	return &PoolId{BatchAccountName: account, PoolName: name}, nil
+}
diff --git a/lib/provider/file-types.go b/lib/provider/file-types.go
index c1c7d9f..c15051d 100644
--- a/lib/provider/file-types.go
+++ b/lib/provider/file-types.go
@@ -10,7 +10,7 @@ type FileType int
 
 const (
 	FileTypeOther    FileType = iota // outside service directories
-	FileTypeResource                 // matches fileregex (resource or data source at service root)
+	FileTypeResource                 // matches fileregex (resource or data source at service root), or lives in a resource folder
 	FileTypeHelper                   // in service dir but doesn't match fileregex (e.g. parse/, validate/, client/)
 	FileTypeTest                     // _test.go with TestAcc functions
 	FileTypeUnitTest                 // _test.go without TestAcc functions
@@ -49,6 +49,9 @@ func DefaultClassifier(f *File) FileType {
 	}
 
 	if f.InServicePackage() {
+		if InResourceFolder(f.RelPath) {
+			return FileTypeResource
+		}
 		if strings.HasSuffix(f.Name, "_resource.go") || strings.HasSuffix(f.Name, "_data_source.go") {
 			return FileTypeResource
 		}
diff --git a/lib/provider/file.go b/lib/provider/file.go
index 30ed174..4bba348 100644
--- a/lib/provider/file.go
+++ b/lib/provider/file.go
@@ -115,10 +115,34 @@ func (f *File) InServicePackage() bool {
 // ResourcePrefix returns the prefix used for test file discovery.
 // For "batch_account_resource.go" → "batch_account".
 // For "batch_account_data_source.go" → "batch_account_data_source".
+// Files in a resource folder are matched by folder rather than name, see resourceFolderPrefix.
 func (f *File) ResourcePrefix() string {
+	if InResourceFolder(f.RelPath) {
+		return f.resourceFolderPrefix()
+	}
 	return strings.TrimSuffix(f.BaseName, "_resource")
 }
 
+// IsTestFor returns true if this file's name is one of the resource prefixes followed by an acceptance test file
+// suffix, e.g. "batch_account" + "_resource_test". An empty prefix matches any test file (see ResourcePrefix).
+func (f *File) IsTestFor(prefixes []string, suffixes []*regexp.Regexp) bool {
+	for _, prefix := range prefixes {
+		if prefix == "" {
+			return true
+		}
+		if !strings.HasPrefix(f.BaseName, prefix) {
+			continue
+		}
+		remainder := f.BaseName[len(prefix):]
+		for _, re := range suffixes {
+			if re.MatchString(remainder) {
+				return true
+			}
+		}
+	}
+	return false
+}
+
 // IsMigrationFile returns true if this file lives inside a known state migration subdirectory
 // of a service package (e.g. internal/services/storage/migration/storage_queue_v1_to_v2.go).
 func (f *File) IsMigrationFile() bool {
diff --git a/lib/provider/resource_folder.go b/lib/provider/resource_folder.go
new file mode 100644
index 0000000..b0b593e
--- /dev/null
+++ b/lib/provider/resource_folder.go
@@ -0,0 +1,42 @@
+package provider
+
+import (
+	"slices"
+	"strings"
+)
+
+// ResourceFolderGroups are the directories below a service that hold one folder per resource in the resource-per-folder
+// layout. Every file directly inside one of those folders belongs to that resource, whatever it is called:
+//
+//	internal/services/batch/resources/batch_account/{resource.go, r_create.go, r_schema.go, data_source.go, list.go, resource_test.go}
+//	internal/services/managedredis/actions/managed_redis_flush_databases/{action.go, action_test.go}
+var ResourceFolderGroups = []string{"resources", "actions"}
+
+// resourceFolderOwnTests are the files in a resource folder that have tests of their own (data_source.go →
+// data_source_test.go), so a change to one only needs those. A change to any other file in the folder (resource.go, r_*.go,
+// shared models) runs every test in the folder.
+var resourceFolderOwnTests = []string{"data_source.go", "list.go", "action.go", "ephemeral.go"}
+
+// InResourceFolder returns true if relPath sits directly inside a resource folder:
+// internal/services/<service>/<group>/<folder>/<file>, where group is one of ResourceFolderGroups.
+func InResourceFolder(relPath string) bool {
+	for _, prefix := range ServiceDirPrefixes {
+		_, rest, found := strings.Cut("/"+relPath, "/"+prefix+"/")
+		if !found {
+			continue
+		}
+		parts := strings.Split(rest, "/") // <service>/<group>/<folder>/<file>
+		return len(parts) == 4 && slices.Contains(ResourceFolderGroups, parts[1])
+	}
+	return false
+}
+
+// resourceFolderPrefix is ResourcePrefix for a file in a resource folder. The folder already scopes the resource, so only
+// the files with tests of their own keep a prefix ("data_source.go" → "data_source"); everything else returns "", which
+// IsTestFor treats as every test file in the folder.
+func (f *File) resourceFolderPrefix() string {
+	if slices.Contains(resourceFolderOwnTests, f.Name) {
+		return f.BaseName
+	}
+	return ""
+}
diff --git a/lib/provider/resource_folder_test.go b/lib/provider/resource_folder_test.go
new file mode 100644
index 0000000..dffd690
--- /dev/null
+++ b/lib/provider/resource_folder_test.go
@@ -0,0 +1,76 @@
+package provider
+
+import (
+	"regexp"
+	"slices"
+	"testing"
+)
+
+func TestInResourceFolder(t *testing.T) {
+	t.Parallel()
+
+	for path, want := range map[string]bool{
+		"internal/services/batch/resources/batch_account/resource.go":                    true,
+		"internal/services/batch/resources/batch_account/r_create.go":                    true,
+		"internal/services/batch/resources/batch_account/resource_test.go":               true,
+		"internal/services/managedredis/actions/managed_redis_flush_databases/action.go": true,
+		"internal/service/ec2/resources/vpc/resource.go":                                 true,
+
+		"internal/services/batch/batch_account_resource.go":                     false, // flat layout
+		"internal/services/batch/validate/account_name.go":                      false, // helper package
+		"internal/services/logic/parse/action.go":                               false, // helper package that happens to hold an action.go
+		"internal/services/batch/account/resource.go":                           false, // one level down, not in a group
+		"internal/services/batch/resources/helpers.go":                          false, // in the group but not in a folder
+		"internal/services/batch/resources/batch_account/migration/v0_to_v1.go": false, // below the folder
+		"internal/acceptance/resources/thing/resource.go":                       false, // not in a service
+	} {
+		if got := InResourceFolder(path); got != want {
+			t.Errorf("InResourceFolder(%s) = %v, want %v", path, got, want)
+		}
+	}
+}
+
+func TestResourceFolderTests(t *testing.T) {
+	t.Parallel()
+
+	suffixes := []*regexp.Regexp{
+		regexp.MustCompile(`^_resource.*_test$`),
+		regexp.MustCompile(`^_test$`),
+		regexp.MustCompile(`^_list_test$`),
+		regexp.MustCompile(`^_identity_gen_test$`),
+		regexp.MustCompile(`^_data_source_test$`),
+	}
+	const folder = "internal/services/batch/resources/batch_account/"
+	folderTests := []string{"data_source_test", "list_test", "resource_identity_gen_test", "resource_test"}
+
+	for _, tc := range []struct {
+		changed string
+		prefix  string
+		tests   []string
+	}{
+		{changed: "resource.go", prefix: "", tests: folderTests},
+		{changed: "r_update.go", prefix: "", tests: folderTests},
+		{changed: "batch_account.go", prefix: "", tests: folderTests},
+		{changed: "data_source.go", prefix: "data_source", tests: []string{"data_source_test"}},
+		{changed: "list.go", prefix: "list", tests: []string{"list_test"}},
+	} {
+		f := NewFile(folder + tc.changed)
+		if f.Type != FileTypeResource {
+			t.Errorf("%s: type = %s, want [RESOURCE]", tc.changed, f.TypeLabel())
+		}
+		if got := f.ResourcePrefix(); got != tc.prefix {
+			t.Errorf("%s: ResourcePrefix() = %q, want %q", tc.changed, got, tc.prefix)
+		}
+
+		var got []string
+		for _, name := range folderTests {
+			test := NewFile(folder + name + ".go")
+			if test.IsTestFor([]string{f.ResourcePrefix()}, suffixes) {
+				got = append(got, name)
+			}
+		}
+		if !slices.Equal(got, tc.tests) {
+			t.Errorf("%s: matched tests %v, want %v", tc.changed, got, tc.tests)
+		}
+	}
+}

From 8876215c11322bf1e17e0a57afd4b5ff91b9f9bd Mon Sep 17 00:00:00 2001
From: kt <kt@katbyte.me>
Date: Wed, 21 Oct 2026 11:43:53 -0700
Subject: [PATCH 2/3] resource folders: run the folder's tests when its shared
 test setup or migration changes

A change to only a resource folder's test_helpers_test.go found no tests: it holds the configs the folder's tests build on but no tests of its own. 53 azurerm folders have one. It now counts as part of the resource, so a change runs every test in the folder.

In API mode, a change to a resource folder's migration/ package found no tests either: the test prefix was guessed from the migration's file name (feature_resource_v0_to_v1.go to feature_resource), which no file in the folder starts with. Inside a resource folder it is now every test in that folder. AST mode already found them by following resource.go's import.
---
 CHANGELOG.md                                  |  2 +-
 README.md                                     |  1 +
 integration/integration_azurerm_test.go       | 35 +++++++++++++++++++
 integration/integration_test.go               |  2 +-
 .../migration/account_resource_v0_to_v1.go    |  6 ++++
 .../batch/resources/batch_account/resource.go |  5 +++
 .../batch_account/test_helpers_test.go        | 13 +++++++
 lib/provider/file-types.go                    |  4 +++
 lib/provider/file.go                          |  6 ++++
 lib/provider/resource_folder.go               | 23 ++++++++++--
 lib/provider/resource_folder_test.go          | 24 +++++++++++++
 11 files changed, 116 insertions(+), 5 deletions(-)
 create mode 100644 integration/testdata/azurerm/internal/services/batch/resources/batch_account/migration/account_resource_v0_to_v1.go
 create mode 100644 integration/testdata/azurerm/internal/services/batch/resources/batch_account/test_helpers_test.go

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 36aaaca..867132d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,6 @@
 ## Unreleased
 
-- support the azurerm resource-per-folder layout (`internal/services/batch/resources/batch_account/{resource,r_create,data_source}.go`, and `actions/` alongside `resources/`): a change to any file in a resource folder now discovers the tests in that folder, and import tracing from helper packages follows into resource folders
+- support the azurerm resource-per-folder layout (`internal/services/batch/resources/batch_account/{resource,r_create,data_source}.go`, and `actions/` alongside `resources/`): a change to any file in a resource folder, its shared `test_helpers_test.go` or its `migration/` package now discovers the tests in that folder, and import tracing from helper packages follows into resource folders
 - API discovery lists directories at the PR's merge commit rather than the default branch, so tests are found in directories the PR adds or moves files into
 
 ## v1.3.5 (2026-10-20)
diff --git a/README.md b/README.md
index b57ef2d..959070b 100755
--- a/README.md
+++ b/README.md
@@ -353,6 +353,7 @@ Any file directly inside `<service>/resources/<folder>/` or `<service>/actions/<
 
 - a change to `data_source.go`, `list.go`, `action.go` or `ephemeral.go` discovers that file's own tests (`data_source_test.go`, ...)
 - a change to any other file in the folder (`resource.go`, `r_*.go`, shared models) discovers every test file in the folder
+- so does a change to the folder's `test_helpers_test.go`, which holds no tests of its own, only the configs the folder's tests share, or to its `migration/` package
 
 Helper packages such as `parse/` and `validate/` are unaffected, and both layouts can be mixed within a service. The service (and so the build triggered) is still the first directory: `batch`.
 
diff --git a/integration/integration_azurerm_test.go b/integration/integration_azurerm_test.go
index 2898eb4..9ad5aa2 100644
--- a/integration/integration_azurerm_test.go
+++ b/integration/integration_azurerm_test.go
@@ -61,6 +61,12 @@ var azurermPRs = []prDef{
 	{1034, "open", "resource folder: test file changed", []changedFile{
 		{"internal/services/batch/resources/batch_account/resource_test.go", "modified", "@@ -26,3 +26,3 @@"},
 	}},
+	{1035, "open", "resource folder: shared test setup changed", []changedFile{
+		{"internal/services/batch/resources/batch_account/test_helpers_test.go", "modified", ""},
+	}},
+	{1036, "open", "resource folder: state migration changed", []changedFile{
+		{"internal/services/batch/resources/batch_account/migration/account_resource_v0_to_v1.go", "modified", ""},
+	}},
 }
 
 // azurermASTPRs are served for the AST-mode tests; the merge refs for these
@@ -126,6 +132,12 @@ var azurermASTPRs = []prDef{
 	{2019, "open", "resource folder: vendored dependency changed", []changedFile{
 		{"vendor/github.com/hashicorp/go-azure-sdk/resource-manager/batch/2024-07-01/pool/id_pool.go", "modified", ""},
 	}},
+	{2020, "open", "resource folder: shared test setup changed", []changedFile{
+		{"internal/services/batch/resources/batch_account/test_helpers_test.go", "modified", ""},
+	}},
+	{2021, "open", "resource folder: state migration changed", []changedFile{
+		{"internal/services/batch/resources/batch_account/migration/account_resource_v0_to_v1.go", "modified", ""},
+	}},
 }
 
 // conflictedPRs marks the PR numbers the mock serves with mergeable=false
@@ -313,6 +325,18 @@ func TestAPIDiscoveryAzureRM(t *testing.T) {
 			args: []string{"pr", "1030", "-i"},
 			want: []trigger{{"TF_E2E_BATCH", "refs/pull/1030/merge", "(TestAccBatchAccountDataSource_basic|TestAccBatchAccount_basic|TestAccBatchAccount_update)"}},
 		},
+		{
+			// test_helpers_test.go has no tests of its own, only the config the folder's tests build on
+			name: "resource folder shared test setup runs every test in its folder",
+			args: []string{"pr", "1035"},
+			want: []trigger{{"TF_E2E_BATCH", "refs/pull/1035/merge", "(TestAccBatchAccount|TestAccBatchAccountDataSource)"}},
+		},
+		{
+			// the migration's file name (account_resource_v0_to_v1.go) does not match the folder's test file names, the folder does
+			name: "resource folder state migration runs every test in its folder",
+			args: []string{"pr", "1036"},
+			want: []trigger{{"TF_E2E_BATCH", "refs/pull/1036/merge", "(TestAccBatchAccount|TestAccBatchAccountDataSource)"}},
+		},
 	}
 
 	for _, tt := range cases {
@@ -497,6 +521,17 @@ func TestASTDiscoveryAzureRM(t *testing.T) {
 			args: []string{"pr", "2019"},
 			want: []trigger{{"TF_E2E_BATCH", "refs/pull/2019/merge", "(TestAccBatchPool)"}},
 		},
+		{
+			name: "resource folder shared test setup runs every test in its folder",
+			args: []string{"pr", "2020"},
+			want: []trigger{{"TF_E2E_BATCH", "refs/pull/2020/merge", "(TestAccBatchAccount|TestAccBatchAccountDataSource)"}},
+		},
+		{
+			// traced through resource.go, which imports the migration package
+			name: "resource folder state migration runs every test in its folder",
+			args: []string{"pr", "2021"},
+			want: []trigger{{"TF_E2E_BATCH", "refs/pull/2021/merge", "(TestAccBatchAccount|TestAccBatchAccountDataSource)"}},
+		},
 	}
 
 	for _, tt := range cases {
diff --git a/integration/integration_test.go b/integration/integration_test.go
index a1a6c25..af089b0 100644
--- a/integration/integration_test.go
+++ b/integration/integration_test.go
@@ -64,7 +64,7 @@ func TestMain(m *testing.M) {
 
 		// build the git upstreams used by the AST-mode tests
 		azurermUpstream = filepath.Join(tmp, "azurerm-upstream")
-		if err := buildGitUpstream("testdata/azurerm", azurermUpstream, 2000, 2020); err != nil {
+		if err := buildGitUpstream("testdata/azurerm", azurermUpstream, 2000, 2025); err != nil {
 			fmt.Fprintf(os.Stderr, "integration test setup: git fixture: %v\n", err)
 			return 1
 		}
diff --git a/integration/testdata/azurerm/internal/services/batch/resources/batch_account/migration/account_resource_v0_to_v1.go b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/migration/account_resource_v0_to_v1.go
new file mode 100644
index 0000000..cfceeff
--- /dev/null
+++ b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/migration/account_resource_v0_to_v1.go
@@ -0,0 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package migration
+
+type AccountV0ToV1 struct{}
diff --git a/integration/testdata/azurerm/internal/services/batch/resources/batch_account/resource.go b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/resource.go
index 4212984..0b6f431 100644
--- a/integration/testdata/azurerm/internal/services/batch/resources/batch_account/resource.go
+++ b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/resource.go
@@ -7,6 +7,7 @@ import (
 	"time"
 
 	"github.com/hashicorp/terraform-provider-azurerm/internal/sdk"
+	"github.com/hashicorp/terraform-provider-azurerm/internal/services/batch/resources/batch_account/migration"
 )
 
 type BatchAccountResource struct{}
@@ -24,3 +25,7 @@ func (r BatchAccountResource) ModelObject() interface{} {
 func (r BatchAccountResource) Read() sdk.ResourceFunc {
 	return sdk.ResourceFunc{Timeout: 5 * time.Minute}
 }
+
+func (r BatchAccountResource) StateUpgraders() []interface{} {
+	return []interface{}{migration.AccountV0ToV1{}}
+}
diff --git a/integration/testdata/azurerm/internal/services/batch/resources/batch_account/test_helpers_test.go b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/test_helpers_test.go
new file mode 100644
index 0000000..ccbac68
--- /dev/null
+++ b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/test_helpers_test.go
@@ -0,0 +1,13 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package batch_account_test
+
+import (
+	"github.com/hashicorp/terraform-provider-azurerm/internal/acceptance"
+)
+
+// template is config the folder's tests build on; a file like this holds no tests of its own
+func (BatchAccountResource) template(data acceptance.TestData) string {
+	return ""
+}
diff --git a/lib/provider/file-types.go b/lib/provider/file-types.go
index c15051d..baf0268 100644
--- a/lib/provider/file-types.go
+++ b/lib/provider/file-types.go
@@ -34,6 +34,10 @@ func DefaultClassifier(f *File) FileType {
 	}
 
 	if strings.HasSuffix(f.RelPath, "_test.go") {
+		if f.isResourceFolderSharedTest() {
+			return FileTypeResource // no tests of its own, only setup for the folder's tests, so a change runs all of them
+		}
+
 		// if we have local path/content, do an in-depth detection for acceptance vs unit test
 		if content, err := f.GetContent(); err == nil {
 			if strings.Contains(string(content), "func TestAcc") {
diff --git a/lib/provider/file.go b/lib/provider/file.go
index 4bba348..b4412e3 100644
--- a/lib/provider/file.go
+++ b/lib/provider/file.go
@@ -5,6 +5,7 @@ package provider
 import (
 	"fmt"
 	"os"
+	"path"
 	"path/filepath"
 	"regexp"
 	"slices"
@@ -152,7 +153,12 @@ func (f *File) IsMigrationFile() bool {
 // MigrationResourcePrefix extracts the resource name from a migration filename by stripping
 // the version-transition suffix (e.g. "_v0_to_v1").
 // For "storage_queue_v1_to_v2" -> "storage_queue".
+// A migration package inside a resource folder returns "", every test in that folder, as the folder already names the resource.
 func (f *File) MigrationResourcePrefix() string {
+	if isResourceFolder(path.Dir(path.Dir(f.RelPath))) {
+		return ""
+	}
+
 	return regexp.MustCompile(`_v\d+_to_v\d+$`).ReplaceAllString(f.BaseName, "")
 }
 
diff --git a/lib/provider/resource_folder.go b/lib/provider/resource_folder.go
index b0b593e..577f78a 100644
--- a/lib/provider/resource_folder.go
+++ b/lib/provider/resource_folder.go
@@ -1,6 +1,7 @@
 package provider
 
 import (
+	"path"
 	"slices"
 	"strings"
 )
@@ -17,20 +18,36 @@ var ResourceFolderGroups = []string{"resources", "actions"}
 // shared models) runs every test in the folder.
 var resourceFolderOwnTests = []string{"data_source.go", "list.go", "action.go", "ephemeral.go"}
 
+// resourceFolderSharedTests are the test files in a resource folder that hold no tests, only setup the folder's tests share
+// (test_helpers_test.go holds the configs they build on). They count as part of the resource, so a change to one runs every
+// test in the folder.
+var resourceFolderSharedTests = []string{"test_helpers_test.go"}
+
 // InResourceFolder returns true if relPath sits directly inside a resource folder:
 // internal/services/<service>/<group>/<folder>/<file>, where group is one of ResourceFolderGroups.
 func InResourceFolder(relPath string) bool {
+	return isResourceFolder(path.Dir(relPath))
+}
+
+// isResourceFolder returns true if dir is a resource folder: internal/services/<service>/<group>/<folder>.
+func isResourceFolder(dir string) bool {
 	for _, prefix := range ServiceDirPrefixes {
-		_, rest, found := strings.Cut("/"+relPath, "/"+prefix+"/")
+		_, rest, found := strings.Cut("/"+dir, "/"+prefix+"/")
 		if !found {
 			continue
 		}
-		parts := strings.Split(rest, "/") // <service>/<group>/<folder>/<file>
-		return len(parts) == 4 && slices.Contains(ResourceFolderGroups, parts[1])
+		parts := strings.Split(rest, "/") // <service>/<group>/<folder>
+		return len(parts) == 3 && slices.Contains(ResourceFolderGroups, parts[1])
 	}
 	return false
 }
 
+// isResourceFolderSharedTest returns true if f is a test file holding setup its resource folder's tests share, see
+// resourceFolderSharedTests.
+func (f *File) isResourceFolderSharedTest() bool {
+	return slices.Contains(resourceFolderSharedTests, f.Name) && InResourceFolder(f.RelPath)
+}
+
 // resourceFolderPrefix is ResourcePrefix for a file in a resource folder. The folder already scopes the resource, so only
 // the files with tests of their own keep a prefix ("data_source.go" → "data_source"); everything else returns "", which
 // IsTestFor treats as every test file in the folder.
diff --git a/lib/provider/resource_folder_test.go b/lib/provider/resource_folder_test.go
index dffd690..d274f55 100644
--- a/lib/provider/resource_folder_test.go
+++ b/lib/provider/resource_folder_test.go
@@ -53,6 +53,7 @@ func TestResourceFolderTests(t *testing.T) {
 		{changed: "batch_account.go", prefix: "", tests: folderTests},
 		{changed: "data_source.go", prefix: "data_source", tests: []string{"data_source_test"}},
 		{changed: "list.go", prefix: "list", tests: []string{"list_test"}},
+		{changed: "test_helpers_test.go", prefix: "", tests: folderTests}, // setup the folder's tests share
 	} {
 		f := NewFile(folder + tc.changed)
 		if f.Type != FileTypeResource {
@@ -74,3 +75,26 @@ func TestResourceFolderTests(t *testing.T) {
 		}
 	}
 }
+
+func TestResourceFolderSharedTestsOutsideAFolder(t *testing.T) {
+	t.Parallel()
+
+	// only a resource folder's test_helpers_test.go is setup for the folder; anywhere else it is an ordinary test file
+	if f := NewFile("internal/services/batch/test_helpers_test.go"); f.Type != FileTypeTest {
+		t.Errorf("type = %s, want [TEST]", f.TypeLabel())
+	}
+}
+
+func TestMigrationResourcePrefix(t *testing.T) {
+	t.Parallel()
+
+	for path, want := range map[string]string{
+		"internal/services/storage/migration/storage_queue_v1_to_v2.go":                                                 "storage_queue",
+		"internal/services/appconfiguration/resources/app_configuration_feature/migration/feature_resource_v0_to_v1.go": "", // the folder names the resource
+	} {
+		f := NewFile(path)
+		if got := f.MigrationResourcePrefix(); got != want {
+			t.Errorf("MigrationResourcePrefix(%s) = %q, want %q", path, got, want)
+		}
+	}
+}

From e4236d16cb3b07953f27a102d46a83e768e46060 Mon Sep 17 00:00:00 2001
From: kt <kt@katbyte.me>
Date: Mon, 26 Oct 2026 20:19:23 -0700
Subject: [PATCH 3/3] resource folders: a package nested in a folder
 (migration/) is always a helper, so its folder's tests run in both modes

azurerm's fileregex matches everything under resources/, and its newest refactor PRs name migration files like notification_hub_resource.go. Both turned a folder's migration/ files into resource files with no tests beside them, so a migration-only change triggered nothing in API or AST mode.

A file in a package nested inside a resource folder is now a helper whatever its name or the regex says, the AST resource check asks the classifier instead of re-doing the regex, and the azurerm integration suite runs with azurerm's real regex and gains a migration file named like a resource.
---
 README.md                                     |  2 +
 cli/flags.go                                  |  4 +-
 cli/pr-ast.go                                 | 19 +++++----
 integration/integration_azurerm_test.go       | 42 +++++++++++++------
 .../migration/account_resource.go             |  7 ++++
 .../batch/resources/batch_account/resource.go |  2 +-
 lib/provider/file-types.go                    |  5 ++-
 lib/provider/file.go                          |  3 +-
 lib/provider/resource_folder.go               | 12 ++++++
 lib/provider/resource_folder_test.go          | 35 ++++++++++++++++
 10 files changed, 104 insertions(+), 27 deletions(-)
 create mode 100644 integration/testdata/azurerm/internal/services/batch/resources/batch_account/migration/account_resource.go

diff --git a/README.md b/README.md
index 959070b..7bd2a45 100755
--- a/README.md
+++ b/README.md
@@ -357,6 +357,8 @@ Any file directly inside `<service>/resources/<folder>/` or `<service>/actions/<
 
 Helper packages such as `parse/` and `validate/` are unaffected, and both layouts can be mixed within a service. The service (and so the build triggered) is still the first directory: `batch`.
 
+Inside a resource folder the layout decides, not `--fileregex` or the file name: azurerm's regex matches every file under `resources/`, and a migration file may be called `notification_hub_resource.go`; neither turns a `migration/` file into a resource file whose own directory is searched for tests.
+
 ### Test Output
 
 Discovered tests are grouped by service and displayed with padded service names for alignment:
diff --git a/cli/flags.go b/cli/flags.go
index fcb41ff..15fed82 100755
--- a/cli/flags.go
+++ b/cli/flags.go
@@ -333,7 +333,9 @@ func GetFlags() *FlagData {
 	// Set the global File classifier using the configured regex
 	provider.Classifier = func(file *provider.File) provider.FileType {
 		t := provider.DefaultClassifier(file)
-		if t == provider.FileTypeHelper && f.DiscoveryConfig.FileRegEx != nil && f.DiscoveryConfig.FileRegEx.MatchString(file.RelPath) {
+		// the regex never promotes a package nested inside a resource folder (its migration/): those stay helpers so the folder's
+		// tests are reached through them, and azurerm's regex is loose enough to match everything under resources/
+		if t == provider.FileTypeHelper && f.DiscoveryConfig.FileRegEx != nil && f.DiscoveryConfig.FileRegEx.MatchString(file.RelPath) && !provider.BelowResourceFolder(file.RelPath) {
 			return provider.FileTypeResource
 		}
 		return t
diff --git a/cli/pr-ast.go b/cli/pr-ast.go
index f01ed66..b47257b 100644
--- a/cli/pr-ast.go
+++ b/cli/pr-ast.go
@@ -310,7 +310,7 @@ func (dc *AstDiscoveryContext) traceImportsToResourceFiles(helperFiles []provide
 
 				// if we have no symbol info, fall back to package-level matching
 				if len(symbols) == 0 {
-					if dc.isResourceFile(relPath) {
+					if isResourceFile(relPath) {
 						dir := filepath.ToSlash(filepath.Dir(relPath))
 						result[dir] = append(result[dir], relPath)
 						clog.Log.Debugf("    traced: %s imports %s (depth %d, package-level)", relPath, pkgPath, depth+1)
@@ -350,7 +350,7 @@ func (dc *AstDiscoveryContext) traceImportsToResourceFiles(helperFiles []provide
 				}
 
 				// this file uses a changed symbol
-				if dc.isResourceFile(relPath) {
+				if isResourceFile(relPath) {
 					// it's a resource file — add to results
 					dir := filepath.ToSlash(filepath.Dir(relPath))
 					result[dir] = append(result[dir], relPath)
@@ -378,10 +378,11 @@ func (dc *AstDiscoveryContext) traceImportsToResourceFiles(helperFiles []provide
 	return result
 }
 
-// isResourceFile returns true if the repo-relative path is a file whose sibling tests should run when it is affected:
-// it matches the fileregex (resource at the service root), or it lives in a resource folder.
-func (dc *AstDiscoveryContext) isResourceFile(relPath string) bool {
-	return dc.Config.FileRegEx.MatchString(relPath) || provider.InResourceFolder(relPath)
+// isResourceFile returns true if the repo-relative path is a file whose sibling tests should run when it is affected: one the
+// classifier calls a resource, as it matches the fileregex at the service root or lives in a resource folder. A package nested
+// inside a folder (migration/) is a helper, so tracing carries on through it to the folder.
+func isResourceFile(relPath string) bool {
+	return provider.NewFile(relPath).Type == provider.FileTypeResource
 }
 
 func (dc *AstDiscoveryContext) SortedTestFiles() []*provider.File {
@@ -499,7 +500,7 @@ func (dc *AstDiscoveryContext) TraceHelperFiles(helperFiles []provider.File) {
 		if entries, err := os.ReadDir(filepath.Join(dc.RepoPath, dir)); err == nil {
 			for _, entry := range entries {
 				if !entry.IsDir() && strings.HasSuffix(entry.Name(), ".go") {
-					if dc.isResourceFile(filepath.ToSlash(filepath.Join(dir, entry.Name()))) {
+					if isResourceFile(filepath.ToSlash(filepath.Join(dir, entry.Name()))) {
 						isSamePkg = true
 						break
 					}
@@ -547,7 +548,7 @@ func (dc *AstDiscoveryContext) TraceHelperFiles(helperFiles []provider.File) {
 				continue
 			}
 			relPath := filepath.ToSlash(filepath.Join(dir, entry.Name()))
-			if !dc.isResourceFile(relPath) {
+			if !isResourceFile(relPath) {
 				continue
 			}
 
@@ -729,7 +730,7 @@ func (dc *AstDiscoveryContext) TraceVendorFiles(vendorFiles []provider.File) {
 			}
 			relPath = filepath.ToSlash(relPath)
 
-			if !dc.isResourceFile(relPath) {
+			if !isResourceFile(relPath) {
 				return nil
 			}
 
diff --git a/integration/integration_azurerm_test.go b/integration/integration_azurerm_test.go
index 9ad5aa2..b7f7f8a 100644
--- a/integration/integration_azurerm_test.go
+++ b/integration/integration_azurerm_test.go
@@ -2,7 +2,6 @@ package integration
 
 import (
 	"encoding/json"
-	"maps"
 	"regexp"
 	"strings"
 	"testing"
@@ -67,6 +66,9 @@ var azurermPRs = []prDef{
 	{1036, "open", "resource folder: state migration changed", []changedFile{
 		{"internal/services/batch/resources/batch_account/migration/account_resource_v0_to_v1.go", "modified", ""},
 	}},
+	{1037, "open", "resource folder: state migration named like a resource changed", []changedFile{
+		{"internal/services/batch/resources/batch_account/migration/account_resource.go", "modified", ""},
+	}},
 }
 
 // azurermASTPRs are served for the AST-mode tests; the merge refs for these
@@ -138,6 +140,9 @@ var azurermASTPRs = []prDef{
 	{2021, "open", "resource folder: state migration changed", []changedFile{
 		{"internal/services/batch/resources/batch_account/migration/account_resource_v0_to_v1.go", "modified", ""},
 	}},
+	{2022, "open", "resource folder: state migration named like a resource changed", []changedFile{
+		{"internal/services/batch/resources/batch_account/migration/account_resource.go", "modified", ""},
+	}},
 }
 
 // conflictedPRs marks the PR numbers the mock serves with mergeable=false
@@ -151,6 +156,9 @@ func azurermEnv(gh *mockGitHub, tc *mockTeamCity) map[string]string {
 		"TCTEST_GITHUB_RAW_URL": gh.rawURL(),
 		// azurerm-style per-service build configurations
 		"TCTEST_BUILD_TYPE_ID_ADD_SERVICE_SUFFIX": "true",
+		// azurerm's own file regex (teamcity-run-tests-on-comment.yaml): it also matches everything under resources/, so the
+		// resource folder cases run against the regex they will meet in production
+		"TCTEST_FILEREGEX": `internal/services/[a-z]*/[_a-zA-Z]*(resource|data_source)`,
 	}
 }
 
@@ -332,11 +340,18 @@ func TestAPIDiscoveryAzureRM(t *testing.T) {
 			want: []trigger{{"TF_E2E_BATCH", "refs/pull/1035/merge", "(TestAccBatchAccount|TestAccBatchAccountDataSource)"}},
 		},
 		{
-			// the migration's file name (account_resource_v0_to_v1.go) does not match the folder's test file names, the folder does
+			// the migration's file name (account_resource_v0_to_v1.go) does not match the folder's test file names, the folder does;
+			// azurerm's regex matches the file too, which must not turn it into a resource file with no tests beside it
 			name: "resource folder state migration runs every test in its folder",
 			args: []string{"pr", "1036"},
 			want: []trigger{{"TF_E2E_BATCH", "refs/pull/1036/merge", "(TestAccBatchAccount|TestAccBatchAccountDataSource)"}},
 		},
+		{
+			// azurerm names some of these account_resource.go, which the _resource.go rule would take for a resource file
+			name: "resource folder state migration named like a resource runs every test in its folder",
+			args: []string{"pr", "1037"},
+			want: []trigger{{"TF_E2E_BATCH", "refs/pull/1037/merge", "(TestAccBatchAccount|TestAccBatchAccountDataSource)"}},
+		},
 	}
 
 	for _, tt := range cases {
@@ -361,22 +376,17 @@ func TestAPIDiscoveryAzureRM(t *testing.T) {
 func TestASTDiscoveryAzureRM(t *testing.T) {
 	t.Parallel()
 
-	// matches only resource/data-source files directly in a service dir, so the
-	// shared dns ipv6_address.go helper stays a helper (the default regex would claim it)
-	const narrowFileRegex = `^internal/services/[a-z]+/[a-z0-9_]+(resource|data_source)\.go$`
-
 	cases := []struct {
 		name     string
 		args     []string
-		extra    map[string]string
 		want     []trigger
 		wantExit int
 	}{
 		{
-			name:  "same-package helper traces to resources using its symbols",
-			args:  []string{"pr", "2001"},
-			extra: map[string]string{"TCTEST_FILEREGEX": narrowFileRegex},
-			want:  []trigger{{"TF_E2E_DNS", "refs/pull/2001/merge", "(TestAccDataSourceDnsAAAARecord|TestAccDnsAAAARecord)"}},
+			// the shared dns ipv6_address.go helper stays a helper under azurerm's regex (the default regex would claim it)
+			name: "same-package helper traces to resources using its symbols",
+			args: []string{"pr", "2001"},
+			want: []trigger{{"TF_E2E_DNS", "refs/pull/2001/merge", "(TestAccDataSourceDnsAAAARecord|TestAccDnsAAAARecord)"}},
 		},
 		{
 			name: "cross-package helper traces through import symbol usage",
@@ -527,11 +537,18 @@ func TestASTDiscoveryAzureRM(t *testing.T) {
 			want: []trigger{{"TF_E2E_BATCH", "refs/pull/2020/merge", "(TestAccBatchAccount|TestAccBatchAccountDataSource)"}},
 		},
 		{
-			// traced through resource.go, which imports the migration package
+			// traced through resource.go, which imports the migration package; azurerm's regex matches the migration file too, which
+			// must not make it a resource file whose own directory is searched for tests instead
 			name: "resource folder state migration runs every test in its folder",
 			args: []string{"pr", "2021"},
 			want: []trigger{{"TF_E2E_BATCH", "refs/pull/2021/merge", "(TestAccBatchAccount|TestAccBatchAccountDataSource)"}},
 		},
+		{
+			// azurerm names some of these account_resource.go, which the _resource.go rule would take for a resource file
+			name: "resource folder state migration named like a resource runs every test in its folder",
+			args: []string{"pr", "2022"},
+			want: []trigger{{"TF_E2E_BATCH", "refs/pull/2022/merge", "(TestAccBatchAccount|TestAccBatchAccountDataSource)"}},
+		},
 	}
 
 	for _, tt := range cases {
@@ -542,7 +559,6 @@ func TestASTDiscoveryAzureRM(t *testing.T) {
 			tc := newMockTeamCity(t)
 			env := azurermEnv(gh, tc)
 			env["TCTEST_LOCAL_REPO_PATH"] = cloneUpstream(t, azurermUpstream)
-			maps.Copy(env, tt.extra)
 
 			res := runTCTest(t, env, tt.args...)
 			if res.exitCode != tt.wantExit {
diff --git a/integration/testdata/azurerm/internal/services/batch/resources/batch_account/migration/account_resource.go b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/migration/account_resource.go
new file mode 100644
index 0000000..e18aff4
--- /dev/null
+++ b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/migration/account_resource.go
@@ -0,0 +1,7 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package migration
+
+// named like a resource file, as azurerm's are (notification_hub/migration/notification_hub_resource.go)
+type AccountV1ToV2 struct{}
diff --git a/integration/testdata/azurerm/internal/services/batch/resources/batch_account/resource.go b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/resource.go
index 0b6f431..4890b30 100644
--- a/integration/testdata/azurerm/internal/services/batch/resources/batch_account/resource.go
+++ b/integration/testdata/azurerm/internal/services/batch/resources/batch_account/resource.go
@@ -27,5 +27,5 @@ func (r BatchAccountResource) Read() sdk.ResourceFunc {
 }
 
 func (r BatchAccountResource) StateUpgraders() []interface{} {
-	return []interface{}{migration.AccountV0ToV1{}}
+	return []interface{}{migration.AccountV0ToV1{}, migration.AccountV1ToV2{}}
 }
diff --git a/lib/provider/file-types.go b/lib/provider/file-types.go
index baf0268..53b600c 100644
--- a/lib/provider/file-types.go
+++ b/lib/provider/file-types.go
@@ -11,7 +11,7 @@ type FileType int
 const (
 	FileTypeOther    FileType = iota // outside service directories
 	FileTypeResource                 // matches fileregex (resource or data source at service root), or lives in a resource folder
-	FileTypeHelper                   // in service dir but doesn't match fileregex (e.g. parse/, validate/, client/)
+	FileTypeHelper                   // in service dir but doesn't match fileregex (e.g. parse/, validate/, client/), or nested in a resource folder (migration/)
 	FileTypeTest                     // _test.go with TestAcc functions
 	FileTypeUnitTest                 // _test.go without TestAcc functions
 	FileTypeVendor                   // under vendor/
@@ -56,6 +56,9 @@ func DefaultClassifier(f *File) FileType {
 		if InResourceFolder(f.RelPath) {
 			return FileTypeResource
 		}
+		if BelowResourceFolder(f.RelPath) {
+			return FileTypeHelper // a package nested in a resource folder (migration/) is a helper of that resource whatever its files are called
+		}
 		if strings.HasSuffix(f.Name, "_resource.go") || strings.HasSuffix(f.Name, "_data_source.go") {
 			return FileTypeResource
 		}
diff --git a/lib/provider/file.go b/lib/provider/file.go
index b4412e3..de615a2 100644
--- a/lib/provider/file.go
+++ b/lib/provider/file.go
@@ -5,7 +5,6 @@ package provider
 import (
 	"fmt"
 	"os"
-	"path"
 	"path/filepath"
 	"regexp"
 	"slices"
@@ -155,7 +154,7 @@ func (f *File) IsMigrationFile() bool {
 // For "storage_queue_v1_to_v2" -> "storage_queue".
 // A migration package inside a resource folder returns "", every test in that folder, as the folder already names the resource.
 func (f *File) MigrationResourcePrefix() string {
-	if isResourceFolder(path.Dir(path.Dir(f.RelPath))) {
+	if BelowResourceFolder(f.RelPath) {
 		return ""
 	}
 
diff --git a/lib/provider/resource_folder.go b/lib/provider/resource_folder.go
index 577f78a..372d727 100644
--- a/lib/provider/resource_folder.go
+++ b/lib/provider/resource_folder.go
@@ -29,6 +29,18 @@ func InResourceFolder(relPath string) bool {
 	return isResourceFolder(path.Dir(relPath))
 }
 
+// BelowResourceFolder returns true if relPath sits in a package nested inside a resource folder, like its migration/ package:
+// internal/services/<service>/<group>/<folder>/<package>/<file>. The file belongs to that resource, but its tests sit up in
+// the folder, not beside it, so it is never a resource file itself whatever the file regex says.
+func BelowResourceFolder(relPath string) bool {
+	for dir := path.Dir(path.Dir(relPath)); dir != "." && dir != "/"; dir = path.Dir(dir) {
+		if isResourceFolder(dir) {
+			return true
+		}
+	}
+	return false
+}
+
 // isResourceFolder returns true if dir is a resource folder: internal/services/<service>/<group>/<folder>.
 func isResourceFolder(dir string) bool {
 	for _, prefix := range ServiceDirPrefixes {
diff --git a/lib/provider/resource_folder_test.go b/lib/provider/resource_folder_test.go
index d274f55..3cb9923 100644
--- a/lib/provider/resource_folder_test.go
+++ b/lib/provider/resource_folder_test.go
@@ -30,6 +30,40 @@ func TestInResourceFolder(t *testing.T) {
 	}
 }
 
+func TestBelowResourceFolder(t *testing.T) {
+	t.Parallel()
+
+	for path, want := range map[string]bool{
+		"internal/services/batch/resources/batch_account/migration/account_resource_v0_to_v1.go": true,
+		"internal/services/managedredis/actions/managed_redis_flush_databases/helpers/flush.go":  true,
+
+		"internal/services/batch/resources/batch_account/resource.go":   false, // in the folder, not below it
+		"internal/services/storage/migration/storage_queue_v1_to_v2.go": false, // flat layout
+		"internal/services/batch/resources/helpers.go":                  false, // in the group but not in a folder
+		"internal/services/batch/validate/account_name.go":              false, // helper package beside the folders
+	} {
+		if got := BelowResourceFolder(path); got != want {
+			t.Errorf("BelowResourceFolder(%s) = %v, want %v", path, got, want)
+		}
+	}
+}
+
+func TestBelowResourceFolderIsAHelper(t *testing.T) {
+	t.Parallel()
+
+	// a package nested in a resource folder is a helper of that resource whatever its files are called, so the folder's tests
+	// are found through it rather than beside it
+	for _, path := range []string{
+		"internal/services/batch/resources/batch_account/migration/account_resource_v0_to_v1.go",
+		"internal/services/notificationhub/resources/notification_hub/migration/notification_hub_resource.go", // the _resource.go rule would claim it
+		"internal/services/appservice/resources/windows_web_app/migration/windows_web_app.go",
+	} {
+		if f := NewFile(path); f.Type != FileTypeHelper {
+			t.Errorf("%s: type = %s, want [HELPER]", path, f.TypeLabel())
+		}
+	}
+}
+
 func TestResourceFolderTests(t *testing.T) {
 	t.Parallel()
 
@@ -91,6 +125,7 @@ func TestMigrationResourcePrefix(t *testing.T) {
 	for path, want := range map[string]string{
 		"internal/services/storage/migration/storage_queue_v1_to_v2.go":                                                 "storage_queue",
 		"internal/services/appconfiguration/resources/app_configuration_feature/migration/feature_resource_v0_to_v1.go": "", // the folder names the resource
+		"internal/services/notificationhub/resources/notification_hub/migration/notification_hub_resource.go":           "",
 	} {
 		f := NewFile(path)
 		if got := f.MigrationResourcePrefix(); got != want {