require jest-matchers in test env

packages/jest-jasmine2/src/__tests__/matchers-test.js

@@ -10,17 +10,10 @@
 'use strict';
 
 jest.disableAutomock();
+const jestExpect = require('jest-matchers').expect;
 
 describe('matchers', () => {
   it('proxies matchers to jest-matchers', () => {
-    // We can't use `expect().toThrow()` because `jest-matchers` error
-    // is thrown in the framework context, and hence `e instanceof Error` will
-    // return `false` and break jasmine
-    try {
-      expect(1).toBe(2);
-      throw new Error('should not be thrown');
-    } catch (e) {
-      expect(e.message).toMatch(/expected.*to be.*===.*/);
-    }
+    expect(() => expect(1).toBe(2)).toThrowError(/expected.*to be.*using '===/);
   });
 });

packages/jest-jasmine2/src/extend_jasmine_expect.js

@@ -0,0 +1,22 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc. All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+'use strict';
+
+jest.deepUnmock('jest-matchers');
+
+const expect = require('jest-matchers').expect;
+
+const jasmineExpect = global.expect;
+
+// extend jasmine matchers with `jest-matchers`
+global.expect = actual => {
+  const jasmineMatchers = jasmineExpect(actual);
+  const jestMatchers = expect(actual);
+  const not = Object.assign(jasmineMatchers.not, jestMatchers.not);
+  return Object.assign(jasmineMatchers, jestMatchers, {not});
+};

packages/jest-jasmine2/src/index.js

@@ -16,11 +16,11 @@ import type Runtime from '../../jest-runtime/src';
 
 const JasmineReporter = require('./reporter');
 
-const expect = require('jest-matchers').expect;
 const fs = require('graceful-fs');
 const jasminePit = require('./jasmine-pit');
 const snapshot = require('jest-snapshot');
 const vm = require('vm');
+const path = require('path');
 
 const CALL_PRINT_LIMIT = 3;
 const LAST_CALL_PRINT_LIMIT = 1;
@@ -293,18 +293,15 @@ function jasmine2(
     }
   });
 
-  // extend jasmine matchers with `jest-matchers`
-  const jasmineExpect = env.expect;
-  env.expect = actual => {
-    const jasmineMatchers = jasmineExpect(actual);
-    const jestMatchers = expect(actual);
-    const not = Object.assign(jasmineMatchers.not, jestMatchers.not);
-    return Object.assign(jasmineMatchers, jestMatchers, {not});
-  };
-
   const snapshotState = snapshot.getSnapshotState(jasmine, testPath);
 
   env.addReporter(reporter);
+
+  // `jest-matchers` should be required inside test environment (vm).
+  // Otherwise if they throw, the `Error` class will differ from the `Error`
+  // class of the test and `error instanceof Error` will return `false`.
+  runtime.requireModule(path.resolve(__dirname, './extend_jasmine_expect.js'));
+
   runtime.requireModule(testPath);
   env.execute();
   return reporter.getResults().then(results => {