Intercept process.stdout and process.stderr

Fixes jestjs#6311

e2e/__tests__/__snapshots__/console.test.js.snap

@@ -12,6 +12,10 @@ exports[`console printing 1`] = `
       This is a warning message.
     console.error __tests__/console.test.js:16
       This is an error message.
+    process.stdout.write __tests__/console.test.js:18
+      write directly to stdout
+    process.stderr.write __tests__/console.test.js:20
+      write directly to stderr
 
 
 "
@@ -37,7 +41,11 @@ exports[`console printing with --verbose 1`] = `
 
   console.error __tests__/console.test.js:16
     This is an error message.
-"
+
+  process.stdout.write __tests__/console.test.js:18
+    write directly to stdout
+  process.stderr.write __tests__/console.test.js:20
+    write directly to stderr"
 `;
 
 exports[`console printing with --verbose 2`] = `

e2e/console/__tests__/console.test.js

@@ -14,4 +14,8 @@ test('works just fine', () => {
   console.warn('This is a warning message.');
 
   console.error('This is an error message.');
+
+  process.stdout.write('write directly to stdout');
+
+  process.stderr.write('write directly to stderr');
 });

packages/jest-runner/package.json

@@ -19,6 +19,7 @@
     "jest-runtime": "^23.1.0",
     "jest-util": "^23.1.0",
     "jest-worker": "^23.0.1",
+    "readable-stream": "^2.3.6",
     "source-map-support": "^0.5.6",
     "throat": "^4.0.0"
   }

packages/jest-runner/src/run_test.js

@@ -26,6 +26,7 @@ import LeakDetector from 'jest-leak-detector';
 import {getTestEnvironment} from 'jest-config';
 import * as docblock from 'jest-docblock';
 import sourcemapSupport from 'source-map-support';
+import {Transform} from 'readable-stream';
 
 type RunTestInternalResult = {
   leakDetector: ?LeakDetector,
@@ -75,7 +76,7 @@ async function runTestInternal(
   let runtime = undefined;
 
   const consoleOut = globalConfig.useStderr ? process.stderr : process.stdout;
-  const consoleFormatter = (type, message) =>
+  const consoleFormatter = (type, message, api, level = 4) =>
     getConsoleOutput(
       config.cwd,
       !!globalConfig.verbose,
@@ -84,21 +85,107 @@ async function runTestInternal(
         [],
         type,
         message,
-        4,
+        level,
         runtime && runtime.getSourceMaps(),
+        api,
       ),
     );
 
   let testConsole;
+  let testStdOut;
+  let testStdErr;
+  let buffer;
 
   if (globalConfig.silent) {
     testConsole = new NullConsole(consoleOut, process.stderr, consoleFormatter);
+    testStdOut = new Transform({
+      transform(chunk, encoding, callback) {
+        callback(null);
+      },
+    });
+    testStdErr = new Transform({
+      transform(chunk, encoding, callback) {
+        callback(null);
+      },
+    });
   } else if (globalConfig.verbose) {
     testConsole = new Console(consoleOut, process.stderr, consoleFormatter);
+    testStdOut = new Transform({
+      transform(chunk, encoding, callback) {
+        callback(null, chunk);
+      },
+    });
+    testStdErr = new Transform({
+      transform(chunk, encoding, callback) {
+        callback(null, chunk);
+      },
+    });
   } else {
-    testConsole = new BufferedConsole(() => runtime && runtime.getSourceMaps());
+    buffer = [];
+    testConsole = new BufferedConsole(
+      () => runtime && runtime.getSourceMaps(),
+      buffer,
+    );
+    testStdOut = new Transform({
+      transform(chunk, encoding, callback) {
+        callback(null, chunk);
+      },
+    });
+    testStdErr = new Transform({
+      transform(chunk, encoding, callback) {
+        callback(null, chunk);
+      },
+    });
   }
 
+  const originalStdOutWrite = testStdOut.write;
+  const originalStdErrWrite = testStdErr.write;
+
+  testStdOut.write = (chunk, ...rest) => {
+    const type = 'write';
+    const message = chunk.toString();
+    const api = 'process.stdout';
+
+    if (buffer) {
+      BufferedConsole.write(
+        buffer,
+        type,
+        message,
+        2,
+        runtime && runtime.getSourceMaps(),
+        api,
+      );
+    } else if (globalConfig.verbose) {
+      consoleOut.write(consoleFormatter(type, message, api, 3));
+    }
+
+    return originalStdOutWrite.call(testStdOut, chunk, ...rest);
+  };
+
+  testStdErr.write = (chunk, ...rest) => {
+    const type = 'write';
+    const message = chunk.toString();
+    const api = 'process.stderr';
+
+    if (buffer) {
+      BufferedConsole.write(
+        buffer,
+        type,
+        message,
+        2,
+        runtime && runtime.getSourceMaps(),
+        api,
+      );
+    } else if (globalConfig.verbose) {
+      consoleOut.write(consoleFormatter(type, message, api, 3));
+    }
+
+    return originalStdErrWrite.call(testStdErr, chunk, ...rest);
+  };
+
+  testStdOut.setEncoding('utf8');
+  testStdErr.setEncoding('utf8');
+
   const environment = new TestEnvironment(config, {console: testConsole});
   const leakDetector = config.detectLeaks
     ? new LeakDetector(environment)
@@ -107,6 +194,15 @@ async function runTestInternal(
   const cacheFS = {[path]: testSource};
   setGlobal(environment.global, 'console', testConsole);
 
+  Object.defineProperty(environment.global.process, 'stdout', {
+    value: testStdOut,
+    writable: false,
+  });
+  Object.defineProperty(environment.global.process, 'stderr', {
+    value: testStdErr,
+    writable: false,
+  });
+
   runtime = new Runtime(config, environment, resolver, cacheFS, {
     collectCoverage: globalConfig.collectCoverage,
     collectCoverageFrom: globalConfig.collectCoverageFrom,

packages/jest-util/src/buffered_console.js

@@ -9,6 +9,7 @@
 
 import type {
   ConsoleBuffer,
+  LogApi,
   LogMessage,
   LogType,
   LogCounters,
@@ -30,8 +31,7 @@ export default class BufferedConsole extends Console {
   _groupDepth: number;
   _getSourceMaps: () => ?SourceMapRegistry;
 
-  constructor(getSourceMaps: () => ?SourceMapRegistry) {
-    const buffer = [];
+  constructor(getSourceMaps: () => ?SourceMapRegistry, buffer = []) {
     super({
       write: message =>
         BufferedConsole.write(buffer, 'log', message, null, getSourceMaps()),
@@ -49,11 +49,13 @@ export default class BufferedConsole extends Console {
     message: LogMessage,
     level: ?number,
     sourceMaps: ?SourceMapRegistry,
+    api: LogApi,
   ) {
     const callsite = getCallsite(level != null ? level : 2, sourceMaps);
     const origin = callsite.getFileName() + ':' + callsite.getLineNumber();
 
     buffer.push({
+      api,
       message,
       origin,
       type,

packages/jest-util/src/get_console_output.js

@@ -17,18 +17,18 @@ export default (root: string, verbose: boolean, buffer: ConsoleBuffer) => {
   const TITLE_INDENT = verbose ? '  ' : '    ';
   const CONSOLE_INDENT = TITLE_INDENT + '  ';
 
-  return buffer.reduce((output, {type, message, origin}) => {
+  return buffer.reduce((output, {api = 'console', type, message, origin}) => {
     origin = slash(path.relative(root, origin));
     message = message
       .split(/\n/)
       .map(line => CONSOLE_INDENT + line)
       .join('\n');
 
-    let typeMessage = 'console.' + type;
+    let typeMessage = `${api}.${type}`;
     if (type === 'warn') {
       message = chalk.yellow(message);
       typeMessage = chalk.yellow(typeMessage);
-    } else if (type === 'error') {
+    } else if (type === 'error' || api === 'process.stderr') {
       message = chalk.red(message);
       typeMessage = chalk.red(typeMessage);
     }

types/Console.js

@@ -7,8 +7,10 @@
  * @flow
  */
 
+export type LogApi = 'console' | 'process.stdout' | 'process.stderr';
 export type LogMessage = string;
 export type LogEntry = {|
+  api: LogApi,
   message: LogMessage,
   origin: string,
   type: LogType,