nodejs · ThanhNguyxn · Feb 7, 2026
diff --git a/lib/internal/test_runner/coverage.js b/lib/internal/test_runner/coverage.js
@@ -37,7 +37,7 @@ const {
   },
 } = require('internal/errors');
 const { matchGlobPattern } = require('internal/fs/glob');
-const { constants: { kMockSearchParam } } = require('internal/test_runner/mock/loader');
+const { constants: { kMockSearchParam }, mocks } = require('internal/test_runner/mock/loader');
 
 const kCoverageFileRegex = /^coverage-(\d+)-(\d{13})-(\d+)\.json$/;
 const kIgnoreRegex = /\/\* node:coverage ignore next (?<count>\d+ )?\*\//;
@@ -498,8 +498,18 @@ class TestCoverage {
       return true;
     }
 
-    const searchParams = new URL(url).searchParams;
-    if (searchParams.get(kMockSearchParam)) {
+    const parsedURL = new URL(url);
+    if (parsedURL.searchParams.get(kMockSearchParam)) {
+      return true;
+    }
+
+    // Check if the base URL (without query params) is registered as a mock.
+    // This handles the case where a CJS module is mocked and imported into
+    // an ESM module - V8 coverage reports the original file URL without the
+    // mock search parameter.
+    parsedURL.search = '';
+    const mock = mocks.get(parsedURL.href);
+    if (mock?.active === true) {
       return true;
     }
 

diff --git a/test/fixtures/test-runner/coverage-with-mock-cjs/dependency.cjs b/test/fixtures/test-runner/coverage-with-mock-cjs/dependency.cjs
@@ -0,0 +1,13 @@
+'use strict';
+
+const data = { type: 'cjs-object' };
+
+function sum(a, b) {
+  return a + b;
+}
+
+function getData() {
+  return data;
+}
+
+module.exports = { sum, getData };
diff --git a/test/fixtures/test-runner/coverage-with-mock-cjs/subject.mjs b/test/fixtures/test-runner/coverage-with-mock-cjs/subject.mjs
@@ -0,0 +1,5 @@
+import { sum, getData } from './dependency.cjs';
+
+export const theModuleSum = (a, b) => sum(a, b);
+
+export const theModuleGetData = () => getData();
diff --git a/test/fixtures/test-runner/output/coverage-with-mock-cjs.mjs b/test/fixtures/test-runner/output/coverage-with-mock-cjs.mjs
@@ -0,0 +1,17 @@
+import { describe, it, mock } from 'node:test';
+
+describe('coverage with mocked CJS module in ESM', async () => {
+  mock.module('../coverage-with-mock-cjs/dependency.cjs', {
+    namedExports: {
+      sum: (a, b) => 42,
+      getData: () => ({ mocked: true }),
+    },
+  });
+
+  const { theModuleSum, theModuleGetData } = await import('../coverage-with-mock-cjs/subject.mjs');
+
+  it('uses mocked CJS exports', (t) => {
+    t.assert.strictEqual(theModuleSum(1, 2), 42);
+    t.assert.deepStrictEqual(theModuleGetData(), { mocked: true });
+  });
+});
diff --git a/test/fixtures/test-runner/output/coverage-with-mock-cjs.snapshot b/test/fixtures/test-runner/output/coverage-with-mock-cjs.snapshot
@@ -0,0 +1,38 @@
+TAP version 13
+# Subtest: coverage with mocked CJS module in ESM
+    # Subtest: uses mocked CJS exports
+    ok 1 - uses mocked CJS exports
+      ---
+      duration_ms: *
+      type: 'test'
+      ...
+    1..1
+ok 1 - coverage with mocked CJS module in ESM
+  ---
+  duration_ms: *
+  type: 'suite'
+  ...
+1..1
+# tests 1
+# suites 1
+# pass 1
+# fail 0
+# cancelled 0
+# skipped 0
+# todo 0
+# duration_ms *
+# start of coverage report
+# -------------------------------------------------------------------------------
+# file                           | line % | branch % | funcs % | uncovered lines
+# -------------------------------------------------------------------------------
+# test                           |        |          |         |
+#  fixtures                      |        |          |         |
+#   test-runner                  |        |          |         |
+#    coverage-with-mock-cjs      |        |          |         |
+#     subject.mjs                | 100.00 |   100.00 |  100.00 |
+#    output                      |        |          |         |
+#     coverage-with-mock-cjs.mjs | 100.00 |   100.00 |  100.00 |
+# -------------------------------------------------------------------------------
+# all files                      | 100.00 |   100.00 |  100.00 |
+# -------------------------------------------------------------------------------
+# end of coverage report
diff --git a/test/test-runner/test-output-coverage-with-mock-cjs.mjs b/test/test-runner/test-output-coverage-with-mock-cjs.mjs
@@ -0,0 +1,25 @@
+// Test that mocked CJS modules imported into ESM are excluded from coverage.
+// This tests the fix for https://github.com/nodejs/node/issues/61709
+import * as common from '../common/index.mjs';
+import * as fixtures from '../common/fixtures.mjs';
+import { spawnAndAssert, defaultTransform, ensureCwdIsProjectRoot } from '../common/assertSnapshot.js';
+
+if (!process.features.inspector) {
+  common.skip('inspector support required');
+}
+
+ensureCwdIsProjectRoot();
+await spawnAndAssert(
+  fixtures.path('test-runner/output/coverage-with-mock-cjs.mjs'),
+  defaultTransform,
+  {
+    flags: [
+      '--disable-warning=ExperimentalWarning',
+      '--test-reporter=tap',
+      '--experimental-transform-types',
+      '--experimental-test-module-mocks',
+      '--experimental-test-coverage',
+      '--test-coverage-exclude=!test/**',
+    ],
+  },
+);