Coverage option for editor support (#5836)

When using the Jest extension in vscode, running coverage is often slow so it would be nice to be able to turn it on and off as needed.

Add a coverage option to the runner.

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ### Features
 
+* `[jest-editor-support]` Add `coverage` option to runner
+  ([#5836](https://github.com/facebook/jest/pull/5836))
 * `[jest-haste-map]` Support extracting dynamic `import`s
   ([#5883](https://github.com/facebook/jest/pull/5883))
 * `[expect]` Improve output format for mismatchedArgs in mock/spy calls.

packages/jest-editor-support/index.d.ts

@@ -13,6 +13,7 @@ export interface SpawnOptions {
 }
 
 export interface Options {
+  coverage?: boolean;
   createProcess?(
     workspace: ProjectWorkspace,
     args: string[],

packages/jest-editor-support/src/Runner.js

@@ -66,6 +66,12 @@ export default class Runner extends EventEmitter {
     if (this.options.testFileNamePattern) {
       args.push(this.options.testFileNamePattern);
     }
+    if (this.options.coverage === true) {
+      args.push('--coverage');
+    }
+    if (this.options.coverage === false) {
+      args.push('--no-coverage');
+    }
 
     const options = {
       shell: this.options.shell,

packages/jest-editor-support/src/__tests__/runner.test.js

@@ -180,6 +180,45 @@ describe('Runner', () => {
       expect((createProcess: any).mock.calls[0][1]).toContain('--watch');
     });
 
+    it('calls createProcess with the --coverage arg when provided', () => {
+      const expected = '--coverage';
+
+      const workspace: any = {};
+      const options = {coverage: true};
+      const sut = new Runner(workspace, options);
+      sut.start(false);
+
+      const args = (createProcess: any).mock.calls[0][1];
+      const index = args.indexOf(expected);
+      expect(index).not.toBe(-1);
+    });
+
+    it('calls createProcess with the ---no-coverage arg when provided and false', () => {
+      const expected = '--no-coverage';
+
+      const workspace: any = {};
+      const options = {coverage: false};
+      const sut = new Runner(workspace, options);
+      sut.start(false);
+
+      const args = (createProcess: any).mock.calls[0][1];
+      const index = args.indexOf(expected);
+      expect(index).not.toBe(-1);
+    });
+
+    it('calls createProcess without the --coverage arg when undefined', () => {
+      const expected = '--coverage';
+
+      const workspace: any = {};
+      const options = {};
+      const sut = new Runner(workspace, options);
+      sut.start(false);
+
+      const args = (createProcess: any).mock.calls[0][1];
+      const index = args.indexOf(expected);
+      expect(index).toBe(-1);
+    });
+
     it('calls createProcess with the --testNamePattern arg when provided', () => {
       const expected = 'testNamePattern';
 

packages/jest-editor-support/src/types.js

@@ -20,6 +20,7 @@ import type {ChildProcess} from 'child_process';
 import type ProjectWorkspace from './project_workspace';
 
 export type Options = {
+  coverage?: boolean,
   createProcess?: (
     workspace: ProjectWorkspace,
     args: Array<string>,