.toThrowError() messages

packages/jest-matcher-utils/src/index.js

@@ -62,7 +62,10 @@ const getType = (value: any): ValueType => {
 const stringify = (obj: any): string => {
   const set = new Set();
   return JSON.stringify(obj, (key, value) => {
-    if (typeof value === 'object' && value !== null) {
+    if (value instanceof Error) {
+      const name = (value.constructor && value.constructor.name) || 'Error';
+      return `${name}: ${value.message}`;
+    } else if (typeof value === 'object' && value !== null) {
       if (
         value &&
         value.constructor &&

packages/jest-matchers/src/__tests__/__snapshots__/toThrowMatchers-test.js.snap

@@ -1,17 +1,84 @@
-exports[`.toThrowError() error class did not throw at all 1`] = `"Expected function to throw an error of type \"Err\"."`;
+exports[`.toThrowError() error class did not throw at all 1`] = `
+"expect(function).toThrowError(type)
 
-exports[`.toThrowError() error class threw, but class did not match 1`] = `"Received \"Err: apple\" but expected Expected function to throw an error of type \"Err2\"."`;
+Expected the function to throw an error of type:
+  \"Err\"
+But it didn\'t throw anything."
+`;
 
-exports[`.toThrowError() error class threw, but should not have 1`] = `"Received \"Err: apple\" but expected the function not to throw an error of type \"Err\"."`;
+exports[`.toThrowError() error class threw, but class did not match 1`] = `
+"expect(function).toThrowError(type)
 
-exports[`.toThrowError() regexp did not throw at all 1`] = `"the function to throw an error matching \"/apple/\"."`;
+Expected the function to throw an error of type:
+  \"Err2\"
+Instead, it threw:
+  \"Err: apple\""
+`;
 
-exports[`.toThrowError() regexp threw, but message did not match 1`] = `"Received \"Error: apple\" but expected the function to throw an error matching \"/banana/\"."`;
+exports[`.toThrowError() error class threw, but should not have 1`] = `
+"expect(function).not.toThrowError(type)
 
-exports[`.toThrowError() regexp threw, but should not have 1`] = `"Received \"Error: apple\" but expected the function not to throw an error matching \"/apple/\"."`;
+Expeced the function not to throw an error of type:
+  \"Err\"
+But it threw:
+  \"Err: apple\""
+`;
 
-exports[`.toThrowError() strings did not throw at all 1`] = `"the function to throw an error matching \"apple\"."`;
+exports[`.toThrowError() invalid arguments 1`] = `
+"Unexpected argument passed. Expected to get
+  \"\\\"string\\\"\", \"\\\"Error type\\\"\" or \"\\\"regexp\\\"\".
+Got: 
+  \"number\": 111."
+`;
 
-exports[`.toThrowError() strings threw, but message did not match 1`] = `"Received \"Error: apple\" but expected the function to throw an error matching \"banana\"."`;
+exports[`.toThrowError() regexp did not throw at all 1`] = `
+"expect(function).toThrowError(regexp)
 
-exports[`.toThrowError() strings threw, but should not have 1`] = `"Received \"Error: apple\" but expected the function not to throw an error matching \"apple\"."`;
+Expected the function to throw an error matching:
+  \"/apple/\"
+But it didn\'t throw anything."
+`;
+
+exports[`.toThrowError() regexp threw, but message did not match 1`] = `
+"expect(function).toThrowError(regexp)
+
+Expected the function to throw an error matching:
+  \"/banana/\"
+Instead, it threw:
+  \"Error: apple\""
+`;
+
+exports[`.toThrowError() regexp threw, but should not have 1`] = `
+"expect(function).not.toThrowError(regexp)
+
+Expeced the function not to throw an error matching:
+  \"/apple/\"
+But it threw:
+  \"Error: apple\""
+`;
+
+exports[`.toThrowError() strings did not throw at all 1`] = `
+"expect(function).toThrowError(string)
+
+Expected the function to throw an error matching:
+  \"apple\"
+But it didn\'t throw anything."
+`;
+
+exports[`.toThrowError() strings threw, but message did not match 1`] = `
+"expect(function).toThrowError(string)
+
+Expected the function to throw an error matching:
+  \"banana\"
+Instead, it threw:
+  \"Error: apple\""
+`;
+
+exports[`.toThrowError() strings threw, but should not have 1`] = `
+"expect(function).not.toThrowError(string)
+
+Expeced the function not to throw an error matching:
+  \"apple\"
+But it threw:
+  \"Error: apple\""
+`;

packages/jest-matchers/src/__tests__/_matchErrorSnapshot.js

@@ -0,0 +1,24 @@
+/**
+ * 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.
+ *
+ * @emails oncall+jsinfra
+ */
+
+'use strict';
+
+module.exports = fn => {
+  let error;
+
+  try {
+    fn();
+  } catch (e) {
+    error = e;
+  }
+
+  expect(error).toBeDefined();
+  expect(error.message).toMatchSnapshot();
+};

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

@@ -13,18 +13,7 @@
 const jestExpect = require('../').expect;
 const {stringify} = require('jest-matcher-utils');
 
-const matchErrorSnapshot = fn => {
-  let error;
-
-  try {
-    fn();
-  } catch (e) {
-    error = e;
-  }
-
-  expect(error).toBeDefined();
-  expect(error.message).toMatchSnapshot();
-};
+const matchErrorSnapshot = require('./_matchErrorSnapshot');
 
 describe('.toBe()', () => {
   it('does not throw', () => {

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

@@ -10,53 +10,38 @@
 
 'use strict';
 
+const jestExpect = require('../').expect;
+const matchErrorSnapshot = require('./_matchErrorSnapshot');
+
 describe('.toThrowError()', () => {
   describe('strings', () => {
     it('passes', () => {
-      expect(() => { throw new Error('apple'); }).toThrowError('apple');
-      expect(() => { throw new Error('banana'); }).not.toThrowError('apple');
-      expect(() => {}).not.toThrowError('apple');
+      jestExpect(() => { throw new Error('apple'); }).toThrowError('apple');
+      jestExpect(() => { throw new Error('banana'); })
+        .not.toThrowError('apple');
+      jestExpect(() => {}).not.toThrowError('apple');
     });
 
     test('did not throw at all', () => {
-      let error;
-      try {
-        expect(() => {}).toThrowError('apple');
-      } catch (e) {
-        error = e;
-      }
-
-      expect(error).toBeDefined();
-      expect(error.message).toMatchSnapshot();
+      matchErrorSnapshot(() => jestExpect(() => {}).toThrowError('apple'));
     });
 
     test('threw, but message did not match', () => {
-      let error;
-      try {
-        expect(() => { throw new Error('apple'); }).toThrowError('banana');
-      } catch (e) {
-        error = e;
-      }
-
-      expect(error).toBeDefined();
-      expect(error.message).toMatchSnapshot();
+      matchErrorSnapshot(() =>
+        jestExpect(() => { throw new Error('apple'); }).toThrowError('banana'),
+      );
     });
 
     it('properly escapes strings when matching against errors', () => {
-      expect(() => { throw new TypeError('"this"? throws.'); })
+      jestExpect(() => { throw new TypeError('"this"? throws.'); })
         .toThrowError('"this"? throws.');
     });
 
     test('threw, but should not have', () => {
-      let error;
-      try {
-        expect(() => { throw new Error('apple'); }).not.toThrowError('apple');
-      } catch (e) {
-        error = e;
-      }
-
-      expect(error).toBeDefined();
-      expect(error.message).toMatchSnapshot();
+      matchErrorSnapshot(() => {
+        jestExpect(() => { throw new Error('apple'); })
+          .not.toThrowError('apple');
+      });
     });
   });
 
@@ -68,39 +53,20 @@ describe('.toThrowError()', () => {
     });
 
     test('did not throw at all', () => {
-      let error;
-      try {
-        expect(() => {}).toThrowError(/apple/);
-      } catch (e) {
-        error = e;
-      }
-
-      expect(error).toBeDefined();
-      expect(error.message).toMatchSnapshot();
+      matchErrorSnapshot(() => jestExpect(() => {}).toThrowError(/apple/));
     });
 
     test('threw, but message did not match', () => {
-      let error;
-      try {
-        expect(() => { throw new Error('apple'); }).toThrowError(/banana/);
-      } catch (e) {
-        error = e;
-      }
-
-      expect(error).toBeDefined();
-      expect(error.message).toMatchSnapshot();
+      matchErrorSnapshot(() => {
+        jestExpect(() => { throw new Error('apple'); }).toThrowError(/banana/);
+      });
     });
 
     test('threw, but should not have', () => {
-      let error;
-      try {
-        expect(() => { throw new Error('apple'); }).not.toThrowError(/apple/);
-      } catch (e) {
-        error = e;
-      }
-
-      expect(error).toBeDefined();
-      expect(error.message).toMatchSnapshot();
+      matchErrorSnapshot(() => {
+        jestExpect(() => { throw new Error('apple'); })
+          .not.toThrowError(/apple/);
+      });
     });
   });
 
@@ -109,46 +75,30 @@ describe('.toThrowError()', () => {
     class Err2 extends Error {}
 
     it('passes', () => {
-      expect(() => { throw new Err(); }).toThrowError(Err);
-      expect(() => { throw new Err(); }).toThrowError(Error);
-      expect(() => { throw new Err(); }).not.toThrowError(Err2);
-      expect(() => {}).not.toThrowError(Err);
+      jestExpect(() => { throw new Err(); }).toThrowError(Err);
+      jestExpect(() => { throw new Err(); }).toThrowError(Error);
+      jestExpect(() => { throw new Err(); }).not.toThrowError(Err2);
+      jestExpect(() => {}).not.toThrowError(Err);
     });
 
     test('did not throw at all', () => {
-      let error;
-      try {
-        expect(() => {}).toThrowError(Err);
-      } catch (e) {
-        error = e;
-      }
-
-      expect(error).toBeDefined();
-      expect(error.message).toMatchSnapshot();
+      matchErrorSnapshot(() => expect(() => {}).toThrowError(Err));
     });
 
     test('threw, but class did not match', () => {
-      let error;
-      try {
-        expect(() => { throw new Err('apple'); }).toThrowError(Err2);
-      } catch (e) {
-        error = e;
-      }
-
-      expect(error).toBeDefined();
-      expect(error.message).toMatchSnapshot();
+      matchErrorSnapshot(() => {
+        jestExpect(() => { throw new Err('apple'); }).toThrowError(Err2);
+      });
     });
 
     test('threw, but should not have', () => {
-      let error;
-      try {
-        expect(() => { throw new Err('apple'); }).not.toThrowError(Err);
-      } catch (e) {
-        error = e;
-      }
-
-      expect(error).toBeDefined();
-      expect(error.message).toMatchSnapshot();
+      matchErrorSnapshot(() => {
+        jestExpect(() => { throw new Err('apple'); }).not.toThrowError(Err);
+      });
     });
   });
+
+  test('invalid arguments', () => {
+    matchErrorSnapshot(() => jestExpect(() => {}).toThrowError(111));
+  });
 });