test: exclude mock from coverage

Fixes: https://github.com/nodejs/node/issues/59112
PR-URL: https://github.com/nodejs/node/pull/59348
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Pietro Marchini <pietro.marchini94@gmail.com>

lib/internal/test_runner/coverage.js

@@ -28,7 +28,7 @@ const {
 const { setupCoverageHooks } = require('internal/util');
 const { tmpdir } = require('os');
 const { join, resolve, relative } = require('path');
-const { fileURLToPath } = require('internal/url');
+const { fileURLToPath, URL } = require('internal/url');
 const { kMappings, SourceMap } = require('internal/source_map/source_map');
 const {
   codes: {
@@ -37,6 +37,7 @@ const {
   },
 } = require('internal/errors');
 const { matchGlobPattern } = require('internal/fs/glob');
+const { kMockSearchParam } = require('internal/test_runner/mock/mock');
 
 const kCoverageFileRegex = /^coverage-(\d+)-(\d{13})-(\d+)\.json$/;
 const kIgnoreRegex = /\/\* node:coverage ignore next (?<count>\d+ )?\*\//;
@@ -497,6 +498,11 @@ class TestCoverage {
       return true;
     }
 
+    const searchParams = new URL(url).searchParams;
+    if (searchParams.get(kMockSearchParam)) {
+      return true;
+    }
+
     // This check filters out the node_modules/ directory, unless it is explicitly included.
     return StringPrototypeIncludes(url, '/node_modules/');
   }

test/fixtures/test-runner/coverage-with-mock/module.js

@@ -0,0 +1,5 @@
+import {getData, sum} from './sum.js'
+
+export const theModuleSum = (a, b) => sum(a,b)
+
+export const theModuleGetData = () => getData()

test/fixtures/test-runner/coverage-with-mock/sum.js

@@ -0,0 +1,9 @@
+// console.log('imported')
+
+const data = { type: 'object' }
+
+// console.log(data)
+
+export const sum = (a, b) => a + b
+
+export const getData = () => data

test/fixtures/test-runner/output/coverage-with-mock.mjs

@@ -0,0 +1,17 @@
+import { describe, it, mock } from 'node:test';
+
+describe('module test with mock', async () => {
+  mock.module('../coverage-with-mock/sum.js', {
+    namedExports: {
+      sum: (a, b) => 1,
+      getData: () => ({}),
+    },
+  });
+
+  const { theModuleSum, theModuleGetData } = await import('../coverage-with-mock/module.js');
+
+  it('tests correct thing', (t) => {
+    t.assert.strictEqual(theModuleSum(1, 2), 1);
+    t.assert.deepStrictEqual(theModuleGetData(), {});
+  });
+});

test/fixtures/test-runner/output/coverage-with-mock.snapshot

@@ -0,0 +1,38 @@
+TAP version 13
+# Subtest: module test with mock
+    # Subtest: tests correct thing
+    ok 1 - tests correct thing
+      ---
+      duration_ms: *
+      type: 'test'
+      ...
+    1..1
+ok 1 - module test with mock
+  ---
+  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      |        |          |         | 
+#     module.js              | 100.00 |   100.00 |  100.00 | 
+#    output                  |        |          |         | 
+#     coverage-with-mock.mjs | 100.00 |   100.00 |  100.00 | 
+# ---------------------------------------------------------------------------
+# all files                  | 100.00 |   100.00 |  100.00 | 
+# ---------------------------------------------------------------------------
+# end of coverage report

test/fixtures/test-runner/output/typescript-coverage.snapshot

@@ -29,11 +29,11 @@ ok 1 - foo
 #  fixtures                   |        |          |         | 
 #   test-runner               |        |          |         | 
 #    coverage                 |        |          |         | 
-#     bar.mts                 |   0.00 |   100.00 |  100.00 | 1-3
+#     bar.mts                 |  33.33 |   100.00 |    0.00 | 2-3
 #     foo.mts                 | 100.00 |   100.00 |  100.00 | 
 #    output                   |        |          |         | 
 #     typescript-coverage.mts | 100.00 |   100.00 |  100.00 | 
 # ----------------------------------------------------------------------------
-# all files                   |  85.29 |   100.00 |   85.71 | 
+# all files                   |  93.55 |   100.00 |   85.71 | 
 # ----------------------------------------------------------------------------
 # end of coverage report

test/parallel/test-runner-output.mjs

@@ -329,6 +329,15 @@ const tests = [
             '--experimental-test-coverage',
             '--test-coverage-exclude=!test/**']
   } : false,
+  process.features.inspector ? {
+    name: 'test-runner/output/coverage-with-mock.mjs',
+    flags: ['--disable-warning=ExperimentalWarning',
+            '--test-reporter=tap',
+            '--experimental-transform-types',
+            '--experimental-test-module-mocks',
+            '--experimental-test-coverage',
+            '--test-coverage-exclude=!test/**']
+  } : false,
 ]
 .filter(Boolean)
 .map(({ flags, name, tty, transform, cwd }) => ({