Add optional options arg to control what is included in error message

mattphillips · Sep 8, 2022 · 13aa927 · 13aa927
1 parent 049d705
commit 13aa927
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diff --git a/README.md b/README.md
@@ -26,8 +26,8 @@ possible in Jest.
 For example:
 
 ```js
-test("returns 2 when adding 1 and 1", () => {
-  expect(1 + 1, "Woah this should be 2!").toBe(3);
+test('returns 2 when adding 1 and 1', () => {
+  expect(1 + 1, 'Woah this should be 2!').toBe(3);
 });
 ```
 
@@ -44,8 +44,8 @@ Expect takes at most one argument.
 For example the same test as above:
 
 ```js
-test("returns 2 when adding 1 and 1", () => {
-  expect(1 + 1, "Woah this should be 2!").toBe(3);
+test('returns 2 when adding 1 and 1', () => {
+  expect(1 + 1, 'Woah this should be 2!').toBe(3);
 });
 ```
 
@@ -101,7 +101,7 @@ Add `jest-expect-message` to your Jest `setupFilesAfterEnv` configuration.
 If you have a custom setup file and want to use this library then add the following to your setup file.
 
 ```js
-import "jest-expect-message";
+import 'jest-expect-message';
 ```
 
 ### Configure Typescript
@@ -131,14 +131,63 @@ Custom message [example](/example) with typescript
 
 ## Usage
 
-- `expect(actual, message)`
+- `expect(actual, message, options?)`
   - `actual`: The value you would normally pass into an `expect` to assert against with a given matcher.
   - `message`: String, the custom message you want to be printed should the `expect` fail.
+  - `options`: An optional object that controls if the custom message prefix and/or if the original matcher message are shown.
+    - type: `{ showPrefix: boolean, showMatcherMessage: boolean }`
+    - Note: `options` is optional and so are both `showPrefix` and `showMatcherMessage` which will be defaulted to `true`.
 
 ```js
-test("returns 2 when adding 1 and 1", () => {
-  expect(1 + 1, "Woah this should be 2!").toBe(3);
+test('returns 2 when adding 1 and 1', () => {
+  expect(1 + 1, 'Woah this should be 2!').toBe(3);
 });
+// ↓ ↓ ↓ ↓ ↓ ↓
+/*
+  ● returns 2 when adding 1 and 1
+
+    Custom message:
+      Woah this should be 2!
+
+    expect(received).toBe(expected) // Object.is equality
+
+    Expected: 3
+    Received: 2
+*/
+```
+
+### ShowPrefix false
+
+```js
+test('returns 2 when adding 1 and 1', () => {
+  expect(1 + 1, 'Woah this should be 2!', { showPrefix: false }).toBe(3);
+});
+// ↓ ↓ ↓ ↓ ↓ ↓
+/*
+  ● returns 2 when adding 1 and 1
+
+    Woah this should be 2!
+
+    expect(received).toBe(expected) // Object.is equality
+
+    Expected: 3
+    Received: 2
+*/
+```
+
+### ShowMatcherMessage false
+
+```js
+test('returns 2 when adding 1 and 1', () => {
+  expect(1 + 1, 'Woah this should be 2!', { showMatcherMessage: false }).toBe(3);
+});
+// ↓ ↓ ↓ ↓ ↓ ↓
+/*
+  ● returns 2 when adding 1 and 1
+
+    Custom message:
+      Woah this should be 2!
+*/
 ```
 
 ## LICENSE

diff --git a/src/withMessage.js b/src/withMessage.js
@@ -9,7 +9,7 @@ class JestAssertionError extends Error {
   }
 }
 
-const wrapMatcher = (matcher, customMessage) => {
+const wrapMatcher = (matcher, customMessage, config) => {
   const newMatcher = (...args) => {
     try {
       return matcher(...args);
@@ -26,44 +26,50 @@ const wrapMatcher = (matcher, customMessage) => {
       const matcherMessage =
         typeof error.matcherResult.message === 'function' ? error.matcherResult.message() : error.matcherResult.message;
 
-      const message = () => 'Custom message:\n  ' + customMessage + '\n\n' + matcherMessage;
+      const messagePrefix = config.showPrefix ? 'Custom message:\n  ' : '';
+
+      const message = () => messagePrefix + customMessage + (config.showMatcherMessage ? '\n\n' + matcherMessage : '');
 
       throw new JestAssertionError({ ...matcherResult, message }, newMatcher);
     }
   };
   return newMatcher;
 };
 
-const wrapMatchers = (matchers, customMessage) => {
+const wrapMatchers = (matchers, customMessage, config) => {
   return Object.keys(matchers).reduce((acc, name) => {
     const matcher = matchers[name];
 
     if (typeof matcher === 'function') {
-      acc[name] = wrapMatcher(matcher, customMessage);
+      acc[name] = wrapMatcher(matcher, customMessage, config);
     } else {
-      acc[name] = wrapMatchers(matcher, customMessage); // recurse on .not/.resolves/.rejects
+      acc[name] = wrapMatchers(matcher, customMessage, config); // recurse on .not/.resolves/.rejects
     }
 
     return acc;
   }, {});
 };
 
-export default expect => {
+export default (expect) => {
   // proxy the expect function
   let expectProxy = Object.assign(
-    (actual, customMessage) => {
+    (actual, customMessage, options = {}) => {
+      const config = {
+        showMatcherMessage: typeof options.showMatcherMessage === 'boolean' ? options.showMatcherMessage : true,
+        showPrefix: typeof options.showPrefix === 'boolean' ? options.showPrefix : true
+      };
       let matchers = expect(actual); // partially apply expect to get all matchers and chain them
       if (customMessage) {
         // only pay the cost of proxying matchers if we received a customMessage
-        matchers = wrapMatchers(matchers, customMessage);
+        matchers = wrapMatchers(matchers, customMessage, config);
       }
 
       return matchers;
     },
     expect // clone additional properties on expect
   );
 
-  expectProxy.extend = o => {
+  expectProxy.extend = (o) => {
     expect.extend(o); // add new matchers to expect
     expectProxy = Object.assign(expectProxy, expect); // clone new asymmetric matchers
   };

diff --git a/src/withMessage.test.js b/src/withMessage.test.js
@@ -35,7 +35,7 @@ describe('withMessage()', () => {
     expect(toBeMock).toHaveBeenCalledWith(1);
   });
 
-  test.each([undefined, ''])('throws original error when given message: %s', message => {
+  test.each([undefined, ''])('throws original error when given message: %s', (message) => {
     expect.assertions(3);
     const originalError = new Error('Boo');
     const toBeMock = jest.fn(() => {
@@ -141,7 +141,7 @@ describe('withMessage()', () => {
 
   it('sets new asymmetric matchers when custom matcher is registered with expect.extend', () => {
     const expectMock = () => {};
-    const extendMock = jest.fn(o => Object.assign(expectMock, o));
+    const extendMock = jest.fn((o) => Object.assign(expectMock, o));
     expectMock.a = 'a';
     expectMock.extend = extendMock;
     const newMatcher = { newMatcher: 'woo' };
@@ -156,4 +156,78 @@ describe('withMessage()', () => {
     expect(extendMock).toHaveBeenCalledWith(newMatcher);
     expect(actual).toContainAllKeys(['a', 'extend', 'newMatcher']);
   });
+
+  test('does not throw error with matcher message when `config.showMatcherMessage` is false', () => {
+    expect.assertions(2);
+    const originalError = new Error('Boo');
+    const matcherMessage = 'expected ACTUAL to not be ACTUAL';
+    originalError.matcherResult = {
+      actual: ACTUAL,
+      expected: 1,
+      message: matcherMessage,
+      pass: false
+    };
+    const toBeMock = jest.fn(() => {
+      throw originalError;
+    });
+    const expectMock = jest.fn(() => ({ toBe: toBeMock }));
+
+    const customMessage = 'should fail';
+    try {
+      withMessage(expectMock)(ACTUAL, customMessage, { showMatcherMessage: false }).toBe(1);
+    } catch (e) {
+      expect(e.message).toInclude(customMessage);
+      expect(e.message).not.toInclude(matcherMessage);
+    }
+  });
+
+  test('does not throw error with custom message prefix when `config.showPrefix` is false', () => {
+    expect.assertions(3);
+    const originalError = new Error('Boo');
+    const matcherMessage = 'expected ACTUAL to not be ACTUAL';
+    originalError.matcherResult = {
+      actual: ACTUAL,
+      expected: 1,
+      message: matcherMessage,
+      pass: false
+    };
+    const toBeMock = jest.fn(() => {
+      throw originalError;
+    });
+    const expectMock = jest.fn(() => ({ toBe: toBeMock }));
+
+    const customMessage = 'should fail';
+    try {
+      withMessage(expectMock)(ACTUAL, customMessage, { showPrefix: false }).toBe(1);
+    } catch (e) {
+      expect(e.message).not.toInclude('Custom message:\n');
+      expect(e.message).toInclude(customMessage);
+      expect(e.message).toInclude(matcherMessage);
+    }
+  });
+
+  test('throws error containing only custom message prefix when `config.showPrefix` and `config.showMatcherMessage` are false', () => {
+    expect.assertions(3);
+    const originalError = new Error('Boo');
+    const matcherMessage = 'expected ACTUAL to not be ACTUAL';
+    originalError.matcherResult = {
+      actual: ACTUAL,
+      expected: 1,
+      message: matcherMessage,
+      pass: false
+    };
+    const toBeMock = jest.fn(() => {
+      throw originalError;
+    });
+    const expectMock = jest.fn(() => ({ toBe: toBeMock }));
+
+    const customMessage = 'should fail';
+    try {
+      withMessage(expectMock)(ACTUAL, customMessage, { showPrefix: false, showMatcherMessage: false }).toBe(1);
+    } catch (e) {
+      expect(e.message).not.toInclude('Custom message:\n');
+      expect(e.message).not.toInclude(matcherMessage);
+      expect(e.message).toInclude(customMessage);
+    }
+  });
 });
diff --git a/types/index.d.ts b/types/index.d.ts
@@ -1,5 +1,9 @@
 declare namespace jest {
   interface Expect {
-      <T = any>(actual: T, message?: string): Matchers<T>;
+    <T = any>(
+      actual: T,
+      message?: string,
+      options?: { showMatcherMessage?: boolean; showPrefix?: boolean }
+    ): Matchers<T>;
   }
 }