chore(cli): also suppress test logging for CLI

packages/aws-cdk-lib/testhelpers/jest-bufferedconsole.ts

@@ -13,7 +13,10 @@ interface ConsoleMessage {
 
 export default class TestEnvironment extends NodeEnvironment implements JestEnvironment<unknown> {
   private log = new Array<ConsoleMessage>();
+
   private originalConsole!: typeof console;
+  private originalStdoutWrite!: typeof process.stdout.write;
+  private originalStderrWrite!: typeof process.stderr.write;
 
   constructor(config: JestEnvironmentConfig, context: EnvironmentContext) {
     super(config, context);
@@ -41,6 +44,8 @@ export default class TestEnvironment extends NodeEnvironment implements JestEnvi
 
     this.log = [];
     this.originalConsole = console;
+    this.originalStdoutWrite = process.stdout.write;
+    this.originalStderrWrite = process.stderr.write;
 
     this.global.console = {
       ...console,
@@ -50,10 +55,30 @@ export default class TestEnvironment extends NodeEnvironment implements JestEnvi
       info: (message) => this.log.push({ type: 'info', message }),
       debug: (message) => this.log.push({ type: 'debug', message }),
     };
+
+    const self = this;
+    process.stdout.write = function (chunk: Buffer | string, enccb?: BufferEncoding | ((error?: Error | null) => void)): void {
+      const encoding = typeof enccb === 'string' ? enccb : 'utf-8';
+      const message = Buffer.isBuffer(chunk) ? chunk.toString(encoding) : chunk;
+      self.log.push({ type: 'log', message: message.replace(/\n$/, '') });
+      if (typeof enccb === 'function') {
+        enccb();
+      }
+    } as any;
+    process.stderr.write = function (chunk: Buffer | string, enccb?: BufferEncoding | ((error?: Error | null) => void)): void {
+      const encoding = typeof enccb === 'string' ? enccb : 'utf-8';
+      const message = Buffer.isBuffer(chunk) ? chunk.toString(encoding) : chunk;
+      self.log.push({ type: 'error', message: message.replace(/\n$/, '') });
+      if (typeof enccb === 'function') {
+        enccb();
+      }
+    } as any;
   }
 
   async teardown() {
     this.global.console = this.originalConsole;
+    process.stdout.write = this.originalStdoutWrite;
+    process.stderr.write = this.originalStderrWrite;
     await super.teardown();
   }
 }
@@ -72,4 +97,3 @@ function fullTestName(test: TestDescription) {
   }
   return ret;
 }
-

packages/aws-cdk/jest.config.js

@@ -31,6 +31,7 @@ const config = {
     // fail because they rely on shared mutable state left by other tests
     // (files on disk, global mocks, etc).
     randomize: true,
+    testEnvironment: './test/jest-bufferedconsole.ts',
 };
 
 // Disable coverage running in the VSCode debug terminal: we never want coverage
@@ -40,4 +41,4 @@ if (process.env.VSCODE_INJECTION) {
     config.collectCoverage = false;
 }
 
-module.exports = config;
+module.exports = config;

packages/aws-cdk/package.json

@@ -92,6 +92,7 @@
     "constructs": "^10.0.0",
     "fast-check": "^3.22.0",
     "jest": "^29.7.0",
+    "jest-environment-node": "^29.7.0",
     "jest-mock": "^29.7.0",
     "madge": "^5.0.2",
     "make-runnable": "^1.4.1",

packages/aws-cdk/test/jest-bufferedconsole.ts

@@ -0,0 +1,99 @@
+/* eslint-disable import/no-extraneous-dependencies */
+/**
+ * A Jest environment that buffers outputs to `console.log()` and only shows it for failing tests.
+ */
+import type { EnvironmentContext, JestEnvironment, JestEnvironmentConfig } from '@jest/environment';
+import { Circus } from '@jest/types';
+import { TestEnvironment as NodeEnvironment } from 'jest-environment-node';
+
+interface ConsoleMessage {
+  type: 'log' | 'error' | 'warn' | 'info' | 'debug';
+  message: string;
+}
+
+export default class TestEnvironment extends NodeEnvironment implements JestEnvironment<unknown> {
+  private log = new Array<ConsoleMessage>();
+
+  private originalConsole!: typeof console;
+  private originalStdoutWrite!: typeof process.stdout.write;
+  private originalStderrWrite!: typeof process.stderr.write;
+
+  constructor(config: JestEnvironmentConfig, context: EnvironmentContext) {
+    super(config, context);
+
+    // We need to set the event handler by assignment in the constructor,
+    // because if we declare it as an async member TypeScript's type derivation
+    // doesn't work properly.
+    (this as JestEnvironment<unknown>).handleTestEvent = (async (event, _state) => {
+      if (event.name === 'test_done' && event.test.errors.length > 0 && this.log.length > 0) {
+        this.originalConsole.log(`[Console output] ${fullTestName(event.test)}\n`);
+        for (const item of this.log) {
+          this.originalConsole[item.type]('    ' + item.message);
+        }
+        this.originalConsole.log('\n');
+      }
+
+      if (event.name === 'test_done') {
+        this.log = [];
+      }
+    }) satisfies Circus.EventHandler;
+  }
+
+  async setup() {
+    await super.setup();
+
+    this.log = [];
+    this.originalConsole = console;
+    this.originalStdoutWrite = process.stdout.write;
+    this.originalStderrWrite = process.stderr.write;
+
+    this.global.console = {
+      ...console,
+      log: (message) => this.log.push({ type: 'log', message }),
+      error: (message) => this.log.push({ type: 'error', message }),
+      warn: (message) => this.log.push({ type: 'warn', message }),
+      info: (message) => this.log.push({ type: 'info', message }),
+      debug: (message) => this.log.push({ type: 'debug', message }),
+    };
+
+    const self = this;
+    process.stdout.write = function (chunk: Buffer | string, enccb?: BufferEncoding | ((error?: Error | null) => void)): void {
+      const encoding = typeof enccb === 'string' ? enccb : 'utf-8';
+      const message = Buffer.isBuffer(chunk) ? chunk.toString(encoding) : chunk;
+      self.log.push({ type: 'log', message: message.replace(/\n$/, '') });
+      if (typeof enccb === 'function') {
+        enccb();
+      }
+    } as any;
+    process.stderr.write = function (chunk: Buffer | string, enccb?: BufferEncoding | ((error?: Error | null) => void)): void {
+      const encoding = typeof enccb === 'string' ? enccb : 'utf-8';
+      const message = Buffer.isBuffer(chunk) ? chunk.toString(encoding) : chunk;
+      self.log.push({ type: 'error', message: message.replace(/\n$/, '') });
+      if (typeof enccb === 'function') {
+        enccb();
+      }
+    } as any;
+  }
+
+  async teardown() {
+    this.global.console = this.originalConsole;
+    process.stdout.write = this.originalStdoutWrite;
+    process.stderr.write = this.originalStderrWrite;
+    await super.teardown();
+  }
+}
+
+// DescribeBlock is not exported from `@jest/types`, so we need to build the parts we are interested in
+type TestDescription = PartialBy<Pick<Circus.TestEntry, 'name' | 'parent'>, 'parent'>;
+
+// Utility type to make specific fields optional
+type PartialBy<T, K extends keyof T> = Omit<T, K> & Partial<Pick<T, K>>
+
+function fullTestName(test: TestDescription) {
+  let ret = test.name;
+  while (test.parent != null && test.parent.name !== 'ROOT_DESCRIBE_BLOCK') {
+    ret = test.parent.name + ' › ' + fullTestName;
+    test = test.parent;
+  }
+  return ret;
+}