make watch plugin initialization errors look nice

CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Fixes
 
 - `[babel-plugin-jest-hoist]` Expand list of whitelisted globals in global mocks ([#8429](https://github.com/facebook/jest/pull/8429)
+- `[jest-core]` Make watch plugin initialization errors look nice ([#8422](https://github.com/facebook/jest/pull/8422))
 
 ### Chore & Maintenance
 

packages/jest-cli/src/cli/index.ts

@@ -36,7 +36,12 @@ export async function run(maybeArgv?: Array<string>, project?: Config.Path) {
   } catch (error) {
     clearLine(process.stderr);
     clearLine(process.stdout);
-    console.error(chalk.red(error.stack));
+    if (error.stack) {
+      console.error(chalk.red(error.stack));
+    } else {
+      console.error(chalk.red(error));
+    }
+
     exit(1);
     throw error;
   }

packages/jest-core/package.json

@@ -31,6 +31,7 @@
     "pirates": "^4.0.1",
     "realpath-native": "^1.1.0",
     "rimraf": "^2.5.4",
+    "slash": "^2.0.0",
     "strip-ansi": "^5.0.0"
   },
   "devDependencies": {
@@ -41,6 +42,7 @@
     "@types/micromatch": "^3.1.0",
     "@types/p-each-series": "^1.0.0",
     "@types/rimraf": "^2.0.2",
+    "@types/slash": "^2.0.0",
     "@types/strip-ansi": "^3.0.0"
   },
   "engines": {

packages/jest-core/src/__tests__/__fixtures__/watch_plugin_throws.js

@@ -0,0 +1,3 @@
+// Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+
+throw new Error('initialization error');

packages/jest-core/src/__tests__/__snapshots__/watch.test.js.snap

@@ -50,6 +50,17 @@ Watch Usage
 ]
 `;
 
+exports[`Watch mode flows makes watch plugin initialization errors look nice 1`] = `
+[Error: Failed to initialize watch plugin "packages/jest-core/src/__tests__/__fixtures__/watch_plugin_throws":
+
+  ● Test suite failed to run
+
+    initialization error
+
+      at Object.<anonymous> (__fixtures__/watch_plugin_throws.js:3:7)
+]
+`;
+
 exports[`Watch mode flows shows prompts for WatchPlugins in alphabetical order 1`] = `
 Array [
   Array [

packages/jest-core/src/__tests__/watch.test.js

@@ -108,7 +108,12 @@ describe('Watch mode flows', () => {
     isInteractive = true;
     jest.doMock('jest-util/build/isInteractive', () => isInteractive);
     watch = require('../watch').default;
-    const config = {roots: [], testPathIgnorePatterns: [], testRegex: []};
+    const config = {
+      rootDir: __dirname,
+      roots: [],
+      testPathIgnorePatterns: [],
+      testRegex: [],
+    };
     pipe = {write: jest.fn()};
     globalConfig = {watch: true};
     hasteMapInstances = [{on: () => {}}];
@@ -571,6 +576,24 @@ describe('Watch mode flows', () => {
     });
   });
 
+  it('makes watch plugin initialization errors look nice', async () => {
+    const pluginPath = `${__dirname}/__fixtures__/watch_plugin_throws`;
+
+    await expect(
+      watch(
+        {
+          ...globalConfig,
+          rootDir: __dirname,
+          watchPlugins: [{config: {}, path: pluginPath}],
+        },
+        contexts,
+        pipe,
+        hasteMapInstances,
+        stdin,
+      ),
+    ).rejects.toMatchSnapshot();
+  });
+
   it.each`
     ok      | option
     ${'✔︎'} | ${'bail'}

packages/jest-core/src/watch.ts

@@ -5,9 +5,11 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+import path from 'path';
 import ansiEscapes from 'ansi-escapes';
 import chalk from 'chalk';
 import exit from 'exit';
+import slash from 'slash';
 import HasteMap, {HasteChangeEvent} from 'jest-haste-map';
 import {formatExecError} from 'jest-message-util';
 import {isInteractive, preRunMessage, specialChars} from 'jest-util';
@@ -171,12 +173,25 @@ export default function watch(
     }
 
     for (const pluginWithConfig of globalConfig.watchPlugins) {
-      const ThirdPartyPlugin = require(pluginWithConfig.path);
-      const plugin: WatchPlugin = new ThirdPartyPlugin({
-        config: pluginWithConfig.config,
-        stdin,
-        stdout: outputStream,
-      });
+      let plugin: WatchPlugin;
+      try {
+        const ThirdPartyPlugin = require(pluginWithConfig.path);
+        plugin = new ThirdPartyPlugin({
+          config: pluginWithConfig.config,
+          stdin,
+          stdout: outputStream,
+        });
+      } catch (error) {
+        const errorWithContext = new Error(
+          `Failed to initialize watch plugin "${chalk.bold(
+            slash(path.relative(process.cwd(), pluginWithConfig.path)),
+          )}":\n\n${formatExecError(error, contexts[0].config, {
+            noStackTrace: false,
+          })}`,
+        );
+        delete errorWithContext.stack;
+        return Promise.reject(errorWithContext);
+      }
       checkForConflicts(watchPluginKeys, plugin, globalConfig);
 
       const hookSubscriber = hooks.getSubscriber();