Coverage option for editor support

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.

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

@@ -66,6 +66,9 @@ export default class Runner extends EventEmitter {
     if (this.options.testFileNamePattern) {
       args.push(this.options.testFileNamePattern);
     }
+    if (this.options.coverage) {
+      args.push('--coverage');
+    }
 
     const options = {
       shell: this.options.shell,

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

@@ -180,6 +180,19 @@ 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 --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>,