chore: intern test ids and abs paths (#24618)

Created named classes for TeleTestStep and TeleTestResult which makes it
easier to analyze in heap snapshot. Also changing `titlePath` from a
closure to a method on TeleTestStep saved ~100Mb out of 2300Mb.

Intern test ids and absolute paths which showed up a lot of duplicate
strings in heap snapshot.

Clear stepMap after processing onTestEnd.

packages/playwright-test/src/isomorphic/stringInternPool.ts

@@ -0,0 +1,28 @@
+/**
+ * Copyright (c) Microsoft Corporation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+export class StringInternPool {
+  private _stringCache = new Map<string, string>();
+
+  public internString(s: string): string {
+    let result = this._stringCache.get(s);
+    if (!result) {
+      this._stringCache.set(s, s);
+      result = s;
+    }
+    return result;
+  }
+}

packages/playwright-test/src/isomorphic/teleReceiver.ts

@@ -20,6 +20,7 @@ import type { FullProject, Metadata } from '../../types/test';
 import type * as reporterTypes from '../../types/testReporter';
 import type { SuitePrivate } from '../../types/reporterPrivate';
 import type { ReporterV2 } from '../reporters/reporterV2';
+import { StringInternPool } from './stringInternPool';
 
 export type JsonLocation = Location;
 export type JsonError = string;
@@ -130,6 +131,7 @@ export class TeleReporterReceiver {
   private _reuseTestCases: boolean;
   private _reportConfig: MergeReporterConfig | undefined;
   private _config!: FullConfig;
+  private _stringPool = new StringInternPool();
 
   constructor(pathSeparator: string, reporter: ReporterV2, reuseTestCases: boolean, reportConfig?: MergeReporterConfig) {
     this._rootSuite = new TeleSuite('', 'root');
@@ -248,6 +250,8 @@ export class TeleReporterReceiver {
     result.error = result.errors?.[0];
     result.attachments = this._parseAttachments(payload.attachments);
     this._reporter.onTestEnd?.(test, result);
+    // Free up the memory as won't see these step ids.
+    result.stepMap = new Map();
   }
 
   private _onStepBegin(testId: string, resultId: string, payload: JsonTestStepStart) {
@@ -255,19 +259,8 @@ export class TeleReporterReceiver {
     const result = test.resultsMap.get(resultId)!;
     const parentStep = payload.parentStepId ? result.stepMap.get(payload.parentStepId) : undefined;
 
-    const step: TestStep = {
+    const location = this._absoluteLocation(payload.location);
-      titlePath: () => {
+    const step = new TeleTestStep(payload, parentStep, location);
-        const parentPath = parentStep?.titlePath() || [];
-        return [...parentPath, payload.title];
-      },
-      title: payload.title,
-      category: payload.category,
-      location: this._absoluteLocation(payload.location),
-      parent: parentStep,
-      startTime: new Date(payload.startTime),
-      duration: -1,
-      steps: [],
-    };
     if (parentStep)
       parentStep.steps.push(step);
     else
@@ -307,6 +300,8 @@ export class TeleReporterReceiver {
   }
 
   private _onExit(): Promise<void> | void {
+    // Free up the memory from the string pool.
+    this._stringPool = new StringInternPool();
     return this._reporter.onExit?.();
   }
 
@@ -403,7 +398,7 @@ export class TeleReporterReceiver {
   private _absolutePath(relativePath?: string): string | undefined {
     if (!relativePath)
       return relativePath;
-    return this._rootDir + this._pathSeparator + relativePath;
+    return this._stringPool.internString(this._rootDir + this._pathSeparator + relativePath);
   }
 
 }
@@ -503,31 +498,57 @@ export class TeleTestCase implements reporterTypes.TestCase {
   }
 
   _createTestResult(id: string): TeleTestResult {
-    const result: TeleTestResult = {
+    const result = new TeleTestResult(this.results.length);
-      retry: this.results.length,
-      parallelIndex: -1,
-      workerIndex: -1,
-      duration: -1,
-      startTime: new Date(),
-      stdout: [],
-      stderr: [],
-      attachments: [],
-      status: 'skipped',
-      statusEx: 'scheduled',
-      steps: [],
-      errors: [],
-      stepMap: new Map(),
-    };
     this.results.push(result);
     this.resultsMap.set(id, result);
     return result;
   }
 }
 
-export type TeleTestResult = reporterTypes.TestResult & {
+class TeleTestStep implements TestStep {
-  stepMap: Map<string, reporterTypes.TestStep>;
+  title: string;
-  statusEx: reporterTypes.TestResult['status'] | 'scheduled' | 'running';
+  category: string;
-};
+  location: Location | undefined;
+  parent: TestStep | undefined;
+  startTime: Date;
+  duration: number = -1;
+  steps: TestStep[] = [];
+
+  constructor(payload: JsonTestStepStart, parentStep: TestStep | undefined, location:  Location | undefined) {
+    this.title = payload.title;
+    this.category = payload.category;
+    this.location = location;
+    this.parent = parentStep;
+    this.startTime = new Date(payload.startTime);
+  }
+
+  titlePath() {
+    const parentPath = this.parent?.titlePath() || [];
+    return [...parentPath, this.title];
+  }
+}
+
+class TeleTestResult implements reporterTypes.TestResult {
+  retry: reporterTypes.TestResult['retry'];
+  parallelIndex: reporterTypes.TestResult['parallelIndex'] = -1;
+  workerIndex: reporterTypes.TestResult['workerIndex'] = -1;
+  duration: reporterTypes.TestResult['duration'] = -1;
+  startTime: reporterTypes.TestResult['startTime'] = new Date();
+  stdout: reporterTypes.TestResult['stdout'] = [];
+  stderr: reporterTypes.TestResult['stderr'] = [];
+  attachments: reporterTypes.TestResult['attachments'] = [];
+  status: TestStatus = 'skipped';
+  steps: TeleTestStep[] = [];
+  errors: reporterTypes.TestResult['errors'] = [];
+  error: reporterTypes.TestResult['error'];
+
+  stepMap: Map<string, reporterTypes.TestStep> = new Map();
+  statusEx: reporterTypes.TestResult['status'] | 'scheduled' | 'running' = 'scheduled';
+
+  constructor(retry: number) {
+    this.retry = retry;
+  }
+}
 
 export type TeleFullProject = FullProject & { id: string };
 

packages/playwright-test/src/reporters/merge.ts

@@ -21,6 +21,7 @@ import type { FullResult } from '../../types/testReporter';
 import type { FullConfigInternal } from '../common/config';
 import type { JsonConfig, JsonEvent, JsonProject, JsonSuite, JsonTestResultEnd } from '../isomorphic/teleReceiver';
 import { TeleReporterReceiver } from '../isomorphic/teleReceiver';
+import { StringInternPool } from '../isomorphic/stringInternPool';
 import { createReporters } from '../runner/reporters';
 import { Multiplexer } from './multiplexer';
 import { ZipFile } from 'playwright-core/lib/utils';
@@ -241,6 +242,7 @@ function printStatusToStdout(message: string) {
 
 class ProjectNamePatcher {
   private _testIds = new Set<string>();
+  private _stringPool = new StringInternPool();
 
   constructor(private _allTestIds: Set<string>, private _projectNameSuffix: string) {
   }
@@ -305,6 +307,6 @@ class ProjectNamePatcher {
     // make them unique and produce a separate test from each blob.
     while (this._allTestIds.has(testId))
       testId = testId + '1';
-    return testId;
+    return this._stringPool.internString(testId);
   }
 }