[test optimization] Fix TIA in parallel mocha

integration-tests/mocha/mocha.spec.js

@@ -2100,6 +2100,60 @@ describe(`mocha@${MOCHA_VERSION}`, function () {
         }).catch(done)
       })
     })
+
+    onlyLatestIt('can skip suites in parallel mode', async () => {
+      receiver.setSuitesToSkip([{
+        type: 'suite',
+        attributes: {
+          suite: 'ci-visibility/test/ci-visibility-test.js',
+        },
+      }])
+
+      const eventsPromise = receiver
+        .gatherPayloadsMaxTimeout(({ url }) => url.endsWith('/api/v2/citestcycle'), (payloads) => {
+          const events = payloads.flatMap(({ payload }) => payload.events)
+          const testSession = events.find(event => event.type === 'test_session_end').content
+          assert.strictEqual(testSession.meta[MOCHA_IS_PARALLEL], 'true')
+          assert.strictEqual(testSession.meta[TEST_ITR_SKIPPING_ENABLED], 'true')
+          assert.strictEqual(testSession.meta[TEST_ITR_TESTS_SKIPPED], 'true')
+          assert.strictEqual(testSession.meta[TEST_ITR_SKIPPING_TYPE], 'suite')
+          assert.strictEqual(testSession.metrics[TEST_ITR_SKIPPING_COUNT], 1)
+
+          const suites = events.filter(event => event.type === 'test_suite_end').map(event => event.content)
+          assert.strictEqual(suites.length, 2)
+
+          const skippedSuite = suites.find(s =>
+            s.resource === 'test_suite.ci-visibility/test/ci-visibility-test.js'
+          )
+          assert.strictEqual(skippedSuite.meta[TEST_STATUS], 'skip')
+          assert.strictEqual(skippedSuite.meta[TEST_SKIPPED_BY_ITR], 'true')
+
+          const runningSuite = suites.find(s =>
+            s.resource === 'test_suite.ci-visibility/test/ci-visibility-test-2.js'
+          )
+          assert.strictEqual(runningSuite.meta[TEST_STATUS], 'pass')
+
+          // Only 1 test ran (from the non-skipped suite)
+          const tests = events.filter(event => event.type === 'test').map(event => event.content)
+          assert.strictEqual(tests.length, 1)
+          assert.strictEqual(tests[0].meta[TEST_STATUS], 'pass')
+        })
+
+      childProcess = exec(
+        'node node_modules/mocha/bin/mocha --parallel --jobs 2' +
+        ' ./ci-visibility/test/ci-visibility-test.js' +
+        ' ./ci-visibility/test/ci-visibility-test-2.js',
+        {
+          cwd,
+          env: getCiVisAgentlessConfig(receiver.port),
+        }
+      )
+
+      await Promise.all([
+        eventsPromise,
+        once(childProcess, 'exit'),
+      ])
+    })
   })
 
   context('error tags', () => {

packages/datadog-instrumentations/src/mocha/main.js

@@ -106,7 +106,7 @@ function getOnStartHandler (isParallel, frameworkVersion) {
     const processArgv = process.argv.slice(2).join(' ')
     const command = `mocha ${processArgv}`
     testSessionStartCh.publish({ command, frameworkVersion })
-    if (!isParallel && skippedSuites.length) {
+    if (skippedSuites.length) {
       itrSkippedSuitesCh.publish({ skippedSuites, frameworkVersion })
     }
   }
@@ -315,8 +315,7 @@ function getExecutionConfiguration (runner, isParallel, frameworkVersion, onFini
     config.isTestManagementTestsEnabled = libraryConfig.isTestManagementEnabled
     config.testManagementAttemptToFixRetries = libraryConfig.testManagementAttemptToFixRetries
     config.isImpactedTestsEnabled = libraryConfig.isImpactedTestsEnabled
-    // ITR is not supported in parallel mode yet
-    config.isSuitesSkippingEnabled = !isParallel && libraryConfig.isSuitesSkippingEnabled
+    config.isSuitesSkippingEnabled = libraryConfig.isSuitesSkippingEnabled
     config.isFlakyTestRetriesEnabled = libraryConfig.isFlakyTestRetriesEnabled
     config.flakyTestRetriesCount = libraryConfig.flakyTestRetriesCount
 
@@ -626,6 +625,13 @@ addHook({
     this.once('start', getOnStartHandler(true, frameworkVersion))
     this.once('end', getOnEndHandler(true))
 
+    // Populate unskippable suites before config is fetched (matches serial mode at Mocha.prototype.run)
+    for (const filePath of files) {
+      if (isMarkedAsUnskippable({ path: filePath })) {
+        unskippableSuites.push(filePath)
+      }
+    }
+
     getExecutionConfiguration(this, true, frameworkVersion, () => {
       if (config.isKnownTestsEnabled) {
         const testSuites = files.map(file => getTestSuitePath(file, process.cwd()))
@@ -640,7 +646,25 @@ addHook({
           config.isEarlyFlakeDetectionFaulty = true
         }
       }
-      run.apply(this, arguments)
+      if (config.isSuitesSkippingEnabled && suitesToSkip.length) {
+        const filteredFiles = []
+        const skippedFiles = []
+        for (const file of files) {
+          const testPath = getTestSuitePath(file, process.cwd())
+          const shouldSkip = suitesToSkip.includes(testPath)
+          const isUnskippable = unskippableSuites.includes(file)
+          if (shouldSkip && !isUnskippable) {
+            skippedFiles.push(testPath)
+          } else {
+            filteredFiles.push(file)
+          }
+        }
+        isSuitesSkipped = skippedFiles.length > 0
+        skippedSuites = skippedFiles
+        run.apply(this, [cb, { files: filteredFiles }])
+      } else {
+        run.apply(this, arguments)
+      }
     })
 
     return this

packages/dd-trace/src/plugins/util/test.js

@@ -150,7 +150,7 @@
 const DD_CI_LIBRARY_CONFIGURATION_ERROR = '_dd.ci.library_configuration_error'
 
 const UNSUPPORTED_TIA_FRAMEWORKS = new Set(['playwright', 'vitest'])
-const UNSUPPORTED_TIA_FRAMEWORKS_PARALLEL_MODE = new Set(['cucumber', 'mocha'])
+const UNSUPPORTED_TIA_FRAMEWORKS_PARALLEL_MODE = new Set(['cucumber'])
 const MINIMUM_FRAMEWORK_VERSION_FOR_EFD = {
   playwright: '>=1.38.0',
 }
@@ -170,7 +170,7 @@
   playwright: '>=1.38.0',
 }
 
 const UNSUPPORTED_ATTEMPT_TO_FIX_FRAMEWORKS_PARALLEL_MODE = new Set([])
 const NOT_SUPPORTED_GRANULARITY_IMPACTED_TESTS_FRAMEWORKS = new Set(['mocha', 'playwright', 'vitest'])
 
 const TEST_LEVEL_EVENT_TYPES = [