try slash to fix Windows CI

Author: jeysal

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__/__snapshots__/watch.test.js.snap

@@ -51,14 +51,14 @@ 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\\":
+[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`] = `

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

@@ -579,9 +579,8 @@ describe('Watch mode flows', () => {
   it('makes watch plugin initialization errors look nice', async () => {
     const pluginPath = `${__dirname}/__fixtures__/watch_plugin_throws`;
 
-    expect.assertions(1);
-    try {
-      await watch(
+    await expect(
+      watch(
         {
           ...globalConfig,
           rootDir: __dirname,
@@ -591,10 +590,8 @@ describe('Watch mode flows', () => {
         pipe,
         hasteMapInstances,
         stdin,
-      );
-    } catch (error) {
-      expect(error.toString().replace(/\\/, '/')).toMatchSnapshot();
-    }
+      ),
+    ).rejects.toMatchSnapshot();
   });
 
   it.each`

packages/jest-core/src/watch.ts

@@ -9,6 +9,7 @@ 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';
@@ -183,7 +184,7 @@ export default function watch(
       } catch (error) {
         const errorWithContext = new Error(
           `Failed to initialize watch plugin "${chalk.bold(
-            path.relative(process.cwd(), pluginWithConfig.path),
+            slash(path.relative(process.cwd(), pluginWithConfig.path)),
           )}":\n\n${formatExecError(error, contexts[0].config, {
             noStackTrace: false,
           })}`,