Honor the white-space: pre comment hint for plain text nodes

.changeset/text-node-white-space-pre-comment.md

@@ -0,0 +1,5 @@
+---
+'@shopify/prettier-plugin-liquid': patch
+---
+
+Fix `{% # white-space: pre %}` comment hint being ignored for plain text nodes, which caused files with meaningful line breaks but no HTML tags (e.g. a `robots.txt.liquid` template) to have their lines incorrectly joined together

packages/prettier-plugin-liquid/src/printer/printer-liquid-html.ts

@@ -55,11 +55,24 @@ import {
   printLiquidDocPrompt,
 } from './print/liquid';
 import { printClosingTagSuffix, printOpeningTagPrefix } from './print/tag';
-import { bodyLines, hasLineBreakInRange, isEmpty, isTextLikeNode, reindent } from './utils';
+import {
+  bodyLines,
+  hasLineBreakInRange,
+  isEmpty,
+  isPreLikeNode,
+  isTextLikeNode,
+  reindent,
+} from './utils';
 
 const { builders, utils } = doc;
 const { fill, group, hardline, dedentToRoot, indent, join, line, softline } = builders;
 
+// `replaceEndOfLine` exists at runtime on both prettier 2 and prettier 3's
+// `doc.utils`, but is missing from prettier 2's type definitions.
+const { replaceEndOfLine } = utils as typeof utils & {
+  replaceEndOfLine: (doc: Doc, replacement?: Doc) => Doc;
+};
+
 const oppositeQuotes = {
   '"': "'",
   "'": '"',
@@ -161,6 +174,14 @@ function printTextNode(
   if (node.value.match(/^\s*$/)) return '';
   const text = node.value;
 
+  if (isPreLikeNode(node)) {
+    return [
+      printOpeningTagPrefix(node, options),
+      replaceEndOfLine(text),
+      printClosingTagSuffix(node, options),
+    ];
+  }
+
   const paragraphs = text
     .split(/(\r?\n){2,}/)
     .filter(Boolean) // removes empty paragraphs (trailingWhitespace)

packages/prettier-plugin-liquid/src/test/text-node-whitespace-pre-comment/fixed.liquid

@@ -0,0 +1,5 @@
+It should not reflow plain text preceded by a `{% # white-space: pre %}` comment
+{% # white-space: pre %}
+User-agent: GPTBot
+User-agent: ClaudeBot
+Allow: /

packages/prettier-plugin-liquid/src/test/text-node-whitespace-pre-comment/index.liquid

@@ -0,0 +1,5 @@
+It should not reflow plain text preceded by a `{% # white-space: pre %}` comment
+{% # white-space: pre %}
+User-agent: GPTBot
+User-agent: ClaudeBot
+Allow: /

packages/prettier-plugin-liquid/src/test/text-node-whitespace-pre-comment/index.spec.ts

@@ -0,0 +1,6 @@
+import { test } from 'vitest';
+import { assertFormattedEqualsFixed } from '../test-helpers';
+
+test('Unit: text-node-whitespace-pre-comment', async () => {
+  await assertFormattedEqualsFixed(__dirname);
+});