Fix reporters' config (#6542)

* Fix `reporters` to handle string params

Documentation shows reporters as `reporters [array<moduleName | [moduleName, options]>]`, the code was incorrectly handling the following cases:

```
// no `string` moduleName
// _addCustomReporters(reporters: Array<ReporterConfig>)
reporters: ['default', 'someother']

// _shouldAddDefaultReporters(reporters?: Array<ReporterConfig>): boolean {
reporters: [['default', {}], 'someother']
```

This fix, use  the already existing `_getReporterProps` to compare `{path} === 'default'`.

* Update CHANGELOG.md

* Update Config.js

* prettier code

* prettier code

* regression test

- config for reporters supports `default`

* Update CHANGELOG.md

CHANGELOG.md

@@ -127,6 +127,7 @@
 - `[expect]` `toEqual` no longer tries to compare non-enumerable symbolic properties, to be consistent with non-symbolic properties. ([#6398](https://github.com/facebook/jest/pull/6398))
 - `[jest-util]` `console.timeEnd` now properly log elapsed time in milliseconds. ([#6456](https://github.com/facebook/jest/pull/6456))
 - `[jest-mock]` Fix `MockNativeMethods` access in react-native `jest.mock()` ([#6505](https://github.com/facebook/jest/pull/6505))
+- `[jest-cli]` Fix `reporters` for `moduleName` = `'default'` ([#6542](https://github.com/facebook/jest/pull/6542))
 
 ### Chore & Maintenance
 

packages/jest-cli/src/TestScheduler.js

@@ -255,10 +255,14 @@ export default class TestScheduler {
     }
   }
 
-  _shouldAddDefaultReporters(reporters?: Array<ReporterConfig>): boolean {
+  _shouldAddDefaultReporters(
+    reporters?: Array<string | ReporterConfig>,
+  ): boolean {
     return (
       !reporters ||
-      !!reporters.find(reporterConfig => reporterConfig[0] === 'default')
+      !!reporters.find(
+        reporter => this._getReporterProps(reporter).path === 'default',
+      )
     );
   }
 
@@ -303,14 +307,12 @@ export default class TestScheduler {
     this.addReporter(new SummaryReporter(this._globalConfig));
   }
 
-  _addCustomReporters(reporters: Array<ReporterConfig>) {
-    const customReporters = reporters.filter(
-      reporterConfig => reporterConfig[0] !== 'default',
-    );
-
-    customReporters.forEach((reporter, index) => {
+  _addCustomReporters(reporters: Array<string | ReporterConfig>) {
+    reporters.forEach((reporter, index) => {
       const {options, path} = this._getReporterProps(reporter);
 
+      if (path === 'default') return;
+
       try {
         // $FlowFixMe
         const Reporter = require(path);
@@ -331,7 +333,7 @@ export default class TestScheduler {
    * to make dealing with them less painful.
    */
   _getReporterProps(
-    reporter: ReporterConfig,
+    reporter: string | ReporterConfig,
   ): {path: string, options?: Object} {
     if (typeof reporter === 'string') {
       return {options: this._options, path: reporter};

packages/jest-cli/src/__tests__/TestScheduler.test.js

@@ -27,6 +27,45 @@ jest.mock('jest-runner-parallel', () => jest.fn(() => mockParallelRunner), {
   virtual: true,
 });
 
+test('config for reporters supports `default`', () => {
+  const undefinedReportersScheduler = new TestScheduler(
+    {
+      reporters: undefined,
+    },
+    {},
+  );
+  const numberOfReporters =
+    undefinedReportersScheduler._dispatcher._reporters.length;
+
+  const stringDefaultReportersScheduler = new TestScheduler(
+    {
+      reporters: ['default'],
+    },
+    {},
+  );
+  expect(stringDefaultReportersScheduler._dispatcher._reporters.length).toBe(
+    numberOfReporters,
+  );
+
+  const defaultReportersScheduler = new TestScheduler(
+    {
+      reporters: [['default', {}]],
+    },
+    {},
+  );
+  expect(defaultReportersScheduler._dispatcher._reporters.length).toBe(
+    numberOfReporters,
+  );
+
+  const emptyReportersScheduler = new TestScheduler(
+    {
+      reporters: [],
+    },
+    {},
+  );
+  expect(emptyReportersScheduler._dispatcher._reporters.length).toBe(0);
+});
+
 test('.addReporter() .removeReporter()', () => {
   const scheduler = new TestScheduler({}, {});
   const reporter = new SummaryReporter();

types/Config.js

@@ -116,7 +116,7 @@ export type InitialOptions = {
   globalSetup?: ?string,
   globalTeardown?: ?string,
   haste?: HasteConfig,
-  reporters?: Array<ReporterConfig | string>,
+  reporters?: Array<string | ReporterConfig>,
   logHeapUsage?: boolean,
   lastCommit?: boolean,
   listTests?: boolean,
@@ -219,7 +219,7 @@ export type GlobalConfig = {|
   passWithNoTests: boolean,
   projects: Array<Glob>,
   replname: ?string,
-  reporters: Array<ReporterConfig>,
+  reporters: Array<string | ReporterConfig>,
   runTestsByPath: boolean,
   rootDir: Path,
   silent: boolean,