diff --git a/bin/proxyquire-bun-shim.cjs b/bin/proxyquire-bun-shim.cjs
index 3f3bd2e8963..0dd3d9ea235 100644
--- a/bin/proxyquire-bun-shim.cjs
+++ b/bin/proxyquire-bun-shim.cjs
@@ -222,7 +222,7 @@ if (
       } catch {
         real = undefined;
       }
-      if (real && typeof real === 'object') {
+      if (real && (typeof real === 'object' || typeof real === 'function')) {
         for (const k of Object.keys(real)) {
           if (!(k in stub)) stub[k] = real[k];
         }
diff --git a/handwritten/spanner/observability-test/batch-transaction.ts b/handwritten/spanner/observability-test/batch-transaction.ts
index 47c124d3922..f3738c67ece 100644
--- a/handwritten/spanner/observability-test/batch-transaction.ts
+++ b/handwritten/spanner/observability-test/batch-transaction.ts
@@ -19,7 +19,7 @@
 import {util} from '@google-cloud/common';
 import * as pfy from '@google-cloud/promisify';
 import * as assert from 'assert';
-import {before, beforeEach, afterEach, describe, it} from 'mocha';
+import {before, after, beforeEach, afterEach, describe, it} from 'mocha';
 import * as extend from 'extend';
 import * as proxyquire from 'proxyquire';
 import * as sinon from 'sinon';
@@ -32,6 +32,11 @@ const {
 const {SimpleSpanProcessor} = require('@opentelemetry/sdk-trace-base');
 import {Session, Spanner} from '../src';
 import * as bt from '../src/batch-transaction';
+const {
+  AsyncLocalStorageContextManager,
+  AsyncHooksContextManager,
+} = require('@opentelemetry/context-async-hooks');
+const {setGlobalContextManager, disableContextAndManager} = require('./helper');
 
 const fakePfy = extend({}, pfy, {
   promisifyAll(klass, options) {
@@ -118,6 +123,17 @@ describe('BatchTransaction', () => {
     exporter: traceExporter,
     spanProcessors: [new SimpleSpanProcessor(traceExporter)],
   });
+  provider.register();
+
+  const contextManager = new (
+    AsyncLocalStorageContextManager || AsyncHooksContextManager
+  )();
+  setGlobalContextManager(contextManager);
+
+  after(async () => {
+    await provider.shutdown();
+    disableContextAndManager(contextManager);
+  });
 
   afterEach(() => {
     traceExporter.reset();
@@ -160,9 +176,11 @@ describe('BatchTransaction', () => {
       assert.strictEqual(spans.length, 2, 'Exactly 2 spans expected');
 
       // Sort the spans by duration.
-      spans.sort((spanA, spanB) => {
-        spanA.duration < spanB.duration;
-      });
+      spans.sort(
+        (spanA, spanB) =>
+          spanA.duration[0] - spanB.duration[0] ||
+          spanA.duration[1] - spanB.duration[1],
+      );
 
       const actualSpanNames: string[] = [];
       spans.forEach(span => {
@@ -224,9 +242,11 @@ describe('BatchTransaction', () => {
       assert.strictEqual(spans.length, 2, 'Exactly 2 spans expected');
 
       // Sort the spans by duration.
-      spans.sort((spanA, spanB) => {
-        spanA.duration < spanB.duration;
-      });
+      spans.sort(
+        (spanA, spanB) =>
+          spanA.duration[0] - spanB.duration[0] ||
+          spanA.duration[1] - spanB.duration[1],
+      );
 
       const actualSpanNames: string[] = [];
       spans.forEach(span => {
diff --git a/handwritten/spanner/observability-test/database.ts b/handwritten/spanner/observability-test/database.ts
index 35737a1efb3..92eed3bd9ba 100644
--- a/handwritten/spanner/observability-test/database.ts
+++ b/handwritten/spanner/observability-test/database.ts
@@ -1229,7 +1229,10 @@ describe('Database', () => {
         assert.ok(
           errorMessage.includes(
             "Cannot read properties of null (reading 'proto')",
-          ) || errorMessage.includes("Cannot read property 'proto' of null"),
+          ) ||
+            errorMessage.includes("Cannot read property 'proto' of null") ||
+            (errorMessage.includes('null is not an object') &&
+              errorMessage.includes('proto')),
         );
 
         // We expect an exception to have been caught as well as a Session event.
diff --git a/handwritten/spanner/observability-test/helper.ts b/handwritten/spanner/observability-test/helper.ts
index 6ce1ba8b6a4..fc610a4f912 100644
--- a/handwritten/spanner/observability-test/helper.ts
+++ b/handwritten/spanner/observability-test/helper.ts
@@ -43,6 +43,9 @@ export const cacheSessionEvents = ['Cache hit: has usable multiplexed session'];
  * and referring to context causes type/value collision errors.
  */
 export function setGlobalContextManager(manager: ContextManager) {
+  if (typeof manager.enable === 'function') {
+    manager.enable();
+  }
   context.setGlobalContextManager(manager);
 }
 
diff --git a/handwritten/spanner/observability-test/spanner.ts b/handwritten/spanner/observability-test/spanner.ts
index a9bb614160f..8e50d6ef623 100644
--- a/handwritten/spanner/observability-test/spanner.ts
+++ b/handwritten/spanner/observability-test/spanner.ts
@@ -47,6 +47,7 @@ const {
   cacheSessionEvents,
 } = require('./helper');
 const {
+  AsyncLocalStorageContextManager,
   AsyncHooksContextManager,
 } = require('@opentelemetry/context-async-hooks');
 
@@ -146,12 +147,10 @@ async function setup(
 
 describe('EndToEnd', async () => {
   const sandbox = sinon.createSandbox();
-  const contextManager = new AsyncHooksContextManager();
+  const contextManager = new (
+    AsyncLocalStorageContextManager || AsyncHooksContextManager
+  )();
   setGlobalContextManager(contextManager);
-  afterEach(async () => {
-    disableContextAndManager(contextManager);
-  });
-
   const traceExporter = new InMemorySpanExporter();
   const sampler = new AlwaysOnSampler();
   const tracerProvider = new NodeTracerProvider({
@@ -177,6 +176,7 @@ describe('EndToEnd', async () => {
     await spanner.close();
     await server.tryShutdown(() => {});
     sandbox.restore();
+    disableContextAndManager(contextManager);
   });
 
   afterEach(async () => {
@@ -2033,9 +2033,25 @@ describe('End to end tracing headers', () => {
   let spannerMock: mock.MockSpanner;
   let observabilityOptions: typeof ObservabilityOptions;
 
+  let provider: InstanceType<typeof NodeTracerProvider>;
+
+  before(() => {
+    const traceExporter = new InMemorySpanExporter();
+    provider = new NodeTracerProvider({
+      sampler: new AlwaysOnSampler(),
+      exporter: traceExporter,
+      spanProcessors: [new SimpleSpanProcessor(traceExporter)],
+    });
+  });
+
+  after(async () => {
+    await provider.shutdown();
+  });
+
   beforeEach(async () => {
     sandbox = sinon.createSandbox();
     observabilityOptions = {
+      tracerProvider: provider,
       enableEndToEndTracing: true,
     };
 
diff --git a/handwritten/spanner/observability-test/table.ts b/handwritten/spanner/observability-test/table.ts
index 26db0ff42b2..36257b34e87 100644
--- a/handwritten/spanner/observability-test/table.ts
+++ b/handwritten/spanner/observability-test/table.ts
@@ -117,9 +117,11 @@ describe('Table', () => {
     );
 
     // Sort the spans by duration.
-    spans.sort((spanA, spanB) => {
-      spanA.duration < spanB.duration;
-    });
+    spans.sort(
+      (spanA, spanB) =>
+        spanA.duration[0] - spanB.duration[0] ||
+        spanA.duration[1] - spanB.duration[1],
+    );
 
     return spans;
   }
diff --git a/handwritten/spanner/observability-test/transaction.ts b/handwritten/spanner/observability-test/transaction.ts
index c89c1b0a925..126b52141b8 100644
--- a/handwritten/spanner/observability-test/transaction.ts
+++ b/handwritten/spanner/observability-test/transaction.ts
@@ -130,9 +130,11 @@ describe('Transaction', () => {
     const spans = traceExporter.getFinishedSpans();
 
     // Sort the spans by startTime.
-    spans.sort((spanA, spanB) => {
-      spanA.startTime < spanB.startTime;
-    });
+    spans.sort(
+      (spanA, spanB) =>
+        spanA.startTime[0] - spanB.startTime[0] ||
+        spanA.startTime[1] - spanB.startTime[1],
+    );
 
     const spanNames: string[] = [];
     const eventNames: string[] = [];
diff --git a/handwritten/spanner/package.json b/handwritten/spanner/package.json
index 8f849dc627c..10116807548 100644
--- a/handwritten/spanner/package.json
+++ b/handwritten/spanner/package.json
@@ -34,10 +34,10 @@
     "docs": "jsdoc -c .jsdoc.js",
     "predocs": "pnpm run compile",
     "lint": "gts check",
-    "system-test": "mocha build/system-test --timeout 1600000",
-    "observability-test": "mocha build/observability-test --timeout 1600000",
-    "cleanup": "mocha scripts/cleanup.js --timeout 30000",
-    "test": "mocha build/test build/test/common build/observability-test",
+    "system-test": "node ../../bin/run-test.cjs build/system-test --timeout 1600000",
+    "observability-test": "node ../../bin/run-test.cjs build/observability-test --timeout 1600000",
+    "cleanup": "node ../../bin/run-test.cjs scripts/cleanup.js --timeout 30000",
+    "test": "node ../../bin/run-test.cjs build/test build/test/common build/observability-test",
     "ycsb": "node ./benchmark/ycsb.js  run -P ./benchmark/workloada -p table=usertable -p cloudspanner.instance=ycsb-instance -p operationcount=100 -p cloudspanner.database=ycsb",
     "fix": "gts fix",
     "clean": "gts clean",
@@ -48,7 +48,7 @@
     "preobservability-test": "pnpm run compile",
     "benchwrapper": "node bin/benchwrapper.js",
     "precompile": "gts clean",
-    "coverage": "c8 mocha build/test build/test/common && c8 report --check-coverage"
+    "coverage": "node ../../bin/run-test.cjs build/test build/test/common && c8 report --check-coverage"
   },
   "dependencies": {
     "@babel/core": "7.27.7",
diff --git a/handwritten/spanner/test/codec.ts b/handwritten/spanner/test/codec.ts
index 43b3e5a2ac5..733aff5cbc2 100644
--- a/handwritten/spanner/test/codec.ts
+++ b/handwritten/spanner/test/codec.ts
@@ -990,7 +990,7 @@ describe('codec', () => {
           value: music.Genre.JAZZ,
           fullName: 'examples.spanner.music.Genre',
         }).toJSON(),
-        1,
+        '1',
       );
     });
   });
diff --git a/handwritten/spanner/test/database.ts b/handwritten/spanner/test/database.ts
index a9d04fa526f..a0fd4991b0d 100644
--- a/handwritten/spanner/test/database.ts
+++ b/handwritten/spanner/test/database.ts
@@ -975,7 +975,10 @@ describe('Database', () => {
         assert.ok(
           errorMessage.includes(
             "Cannot read properties of null (reading 'proto')",
-          ) || errorMessage.includes("Cannot read property 'proto' of null"),
+          ) ||
+            errorMessage.includes("Cannot read property 'proto' of null") ||
+            (errorMessage.includes('null is not an object') &&
+              errorMessage.includes('proto')),
         );
 
         done();
diff --git a/handwritten/spanner/test/helper.ts b/handwritten/spanner/test/helper.ts
index 668df900db9..30d04e189f7 100644
--- a/handwritten/spanner/test/helper.ts
+++ b/handwritten/spanner/test/helper.ts
@@ -125,7 +125,7 @@ describe('helper', () => {
 
       assert.throws(() => {
         replaceProjectIdToken(frozenObj, projectId);
-      }, /Cannot assign to read only property/);
+      }, /Cannot assign to read only property|Attempted to assign to readonly property/);
     });
 
     it('should replace more than one {{projectId}}', () => {
diff --git a/handwritten/spanner/test/partial-result-stream.ts b/handwritten/spanner/test/partial-result-stream.ts
index 032f4e1db3d..dc1938c2057 100644
--- a/handwritten/spanner/test/partial-result-stream.ts
+++ b/handwritten/spanner/test/partial-result-stream.ts
@@ -196,7 +196,10 @@ describe('PartialResultStream', () => {
         // Node 18's assert.deepStrictEqual strictly requires prototype equality,
         // which fails when comparing RowImpl (an Array subclass) with a plain Array literal.
         // Node 20+ relaxed this for Array subclasses with constructor = Array.
-        if (parseInt(process.versions.node.split('.')[0], 10) < 20) {
+        if (
+          parseInt(process.versions.node.split('.')[0], 10) < 20 ||
+          process.versions.bun
+        ) {
           assert.deepStrictEqual([...row], EXPECTED_ROW);
         } else {
           assert.deepStrictEqual(row, EXPECTED_ROW);
@@ -260,7 +263,10 @@ describe('PartialResultStream', () => {
         // Node 18's assert.deepStrictEqual strictly requires prototype equality,
         // which fails when comparing RowImpl (an Array subclass) with a plain Array literal.
         // Node 20+ relaxed this for Array subclasses with constructor = Array.
-        if (parseInt(process.versions.node.split('.')[0], 10) < 20) {
+        if (
+          parseInt(process.versions.node.split('.')[0], 10) < 20 ||
+          process.versions.bun
+        ) {
           assert.deepStrictEqual([...row], EXPECTED_ROW);
         } else {
           assert.deepStrictEqual(row, EXPECTED_ROW);
diff --git a/handwritten/spanner/test/session-pool.ts b/handwritten/spanner/test/session-pool.ts
index d279da8699f..1418b170d50 100644
--- a/handwritten/spanner/test/session-pool.ts
+++ b/handwritten/spanner/test/session-pool.ts
@@ -15,7 +15,7 @@
  */
 
 import * as assert from 'assert';
-import {before, beforeEach, afterEach, describe, it} from 'mocha';
+import {after, before, beforeEach, afterEach, describe, it} from 'mocha';
 import * as events from 'events';
 import PQueue from 'p-queue';
 import * as proxyquire from 'proxyquire';
@@ -29,6 +29,12 @@ import * as sp from '../src/session-pool';
 import {Transaction} from '../src/transaction';
 import {grpc} from 'google-gax';
 const {startTrace} = require('../src/instrument');
+const {
+  AlwaysOnSampler,
+  NodeTracerProvider,
+  InMemorySpanExporter,
+} = require('@opentelemetry/sdk-trace-node');
+const {SimpleSpanProcessor} = require('@opentelemetry/sdk-trace-base');
 
 let pQueueOverride: typeof PQueue | null = null;
 
@@ -613,7 +619,7 @@ describe('SessionPool', () => {
       sessionPool.options.acquireTimeout = 1;
 
       sessionPool._acquires.add = fn => {
-        return new Promise(r => setTimeout(r, 3)).then(fn);
+        return new Promise(resolve => setTimeout(resolve, 3)).then(fn);
       };
 
       try {
@@ -1374,6 +1380,22 @@ describe('SessionPool', () => {
   });
 
   describe('trace annotations on active span', () => {
+    let traceExporter: InstanceType<typeof InMemorySpanExporter>;
+    let provider: InstanceType<typeof NodeTracerProvider>;
+
+    before(() => {
+      traceExporter = new InMemorySpanExporter();
+      provider = new NodeTracerProvider({
+        sampler: new AlwaysOnSampler(),
+        exporter: traceExporter,
+        spanProcessors: [new SimpleSpanProcessor(traceExporter)],
+      });
+    });
+
+    after(async () => {
+      await provider.shutdown();
+    });
+
     beforeEach(() => {
       sessionPool.isOpen = true;
       sessionPool._isValidSession = () => true;
@@ -1381,49 +1403,54 @@ describe('SessionPool', () => {
 
     it('annotations when acquiring a session', done => {
       const topLevelSpanName = 'testSessionPool.acquire';
-      startTrace(topLevelSpanName, {}, async span => {
-        const fakeSession = createSession();
-        const now = Date.now();
-
-        const stub = sandbox
-          .stub(sessionPool, '_getSession')
-          .resolves(fakeSession);
-        const session = await sessionPool._acquire();
-        const [startTime] = stub.getCall(0).args;
-
-        assert(isAround(startTime, now));
-        assert.strictEqual(session, fakeSession);
-
-        await sessionPool._release(session);
-        span.end();
-
-        const events = span.events;
-        assert.strictEqual(!events, false, 'Events must be set');
-        assert.strictEqual(
-          events.length > 0,
-          true,
-          'Expecting at least 1 event',
-        );
-
-        // Sort the events by earliest time of occurence.
-        events.sort((evtA, evtB) => {
-          return evtA.time < evtB.time;
-        });
-
-        const gotEventNames: string[] = [];
-        events.forEach(event => {
-          gotEventNames.push(event.name);
-        });
-
-        const wantEventNames = ['Acquiring session', 'Acquired session'];
-        assert.deepEqual(
-          gotEventNames,
-          wantEventNames,
-          `Mismatched events\n\tGot:  ${gotEventNames}\n\tWant: ${wantEventNames}`,
-        );
+      startTrace(
+        topLevelSpanName,
+        {opts: {tracerProvider: provider}},
+        async span => {
+          const fakeSession = createSession();
+          const now = Date.now();
+
+          const stub = sandbox
+            .stub(sessionPool, '_getSession')
+            .resolves(fakeSession);
+          const session = await sessionPool._acquire();
+          const [startTime] = stub.getCall(0).args;
+
+          assert(isAround(startTime, now));
+          assert.strictEqual(session, fakeSession);
 
-        done();
-      });
+          await sessionPool._release(session);
+          span.end();
+
+          const events = span.events;
+          assert.strictEqual(!events, false, 'Events must be set');
+          assert.strictEqual(
+            events.length > 0,
+            true,
+            'Expecting at least 1 event',
+          );
+
+          // Sort the events by earliest time of occurence.
+          events.sort(
+            (evtA, evtB) =>
+              evtA.time[0] - evtB.time[0] || evtA.time[1] - evtB.time[1],
+          );
+
+          const gotEventNames: string[] = [];
+          events.forEach(event => {
+            gotEventNames.push(event.name);
+          });
+
+          const wantEventNames = ['Acquiring session', 'Acquired session'];
+          assert.deepEqual(
+            gotEventNames,
+            wantEventNames,
+            `Mismatched events\n\tGot:  ${gotEventNames}\n\tWant: ${wantEventNames}`,
+          );
+
+          done();
+        },
+      );
     });
   });
 });