Add Pass & Fail matchers (jest-community#204)

README.md

@@ -183,7 +183,6 @@ test('passes when using an asymmetrical matcher', () => {
 
 #### .pass(message)
 
-_Note: Currently unimplemented_
 
 Passing assertion.
 
@@ -193,7 +192,6 @@ expect().pass('should pass');
 
 #### .fail(message)
 
-_Note: Currently unimplemented_
 
 Failing assertion.
 

src/matchers/fail/__snapshots__/index.test.js.snap

@@ -0,0 +1,5 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`.fail fails with message 1`] = `"This shouldn't fail!"`;
+
+exports[`.fail fails without message 1`] = `"fails by .fail() assertion"`;

src/matchers/fail/index.js

@@ -0,0 +1,10 @@
+import predicate from './predicate';
+
+const failMessage = message => {
+  if (message) return () => message;
+  else return () => 'fails by .fail() assertion';
+};
+
+export default {
+  fail: (expected, message) => ({ pass: predicate(), message: failMessage(message) }),
+};

src/matchers/fail/index.test.js

@@ -0,0 +1,21 @@
+import matcher from './';
+
+expect.extend(matcher);
+
+describe('.fail', () => {
+  test('fails without message', () => {
+    expect(() => expect().fail()).toThrowErrorMatchingSnapshot();
+  });
+  test('fails with message', () => {
+    expect(() => expect().fail("This shouldn't fail!")).toThrowErrorMatchingSnapshot();
+  });
+});
+
+describe('.not.fail', () => {
+  test('does not fail without message', () => {
+    expect().not.fail();
+  });
+  test('does not fail with message', () => {
+    expect().not.fail('this should fail!');
+  });
+});

src/matchers/fail/predicate.js

@@ -0,0 +1 @@
+export default () => false;

src/matchers/fail/predicate.test.js

@@ -0,0 +1,7 @@
+import predicate from './predicate';
+
+describe('fail Predicate', () => {
+  test('returns false', () => {
+    expect(predicate()).toBe(false);
+  });
+});

src/matchers/index.js

@@ -1,3 +1,5 @@
+import failMatcher from './fail';
+import passMatcher from './pass';
 import toBeAfterMatcher from './toBeAfter';
 import toBeArrayMatcher from './toBeArray';
 import toBeArrayOfSizeMatcher from './toBeArrayOfSize';
@@ -60,6 +62,8 @@ import toThrowWithMessageMatcher from './toThrowWithMessage';
 
 // this is absolutely horrible, but all matchers are default exports of an object with the name of the matcher
 
+export const fail = failMatcher.fail;
+export const pass = passMatcher.pass;
 export const toBeAfter = toBeAfterMatcher.toBeAfter;
 export const toBeArray = toBeArrayMatcher.toBeArray;
 export const toBeArrayOfSize = toBeArrayOfSizeMatcher.toBeArrayOfSize;

src/matchers/pass/__snapshots__/index.test.js.snap

@@ -0,0 +1,5 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`.not.pass does not pass, has no message 1`] = `"passes by .pass() assertion"`;
+
+exports[`.not.pass does not.pass, has no message 1`] = `"This should not pass!"`;

src/matchers/pass/index.js

@@ -0,0 +1,10 @@
+import predicate from './predicate';
+
+const passMessage = message => {
+  if (message) return () => message;
+  else return () => 'passes by .pass() assertion';
+};
+
+export default {
+  pass: (expected, message) => ({ pass: predicate(), message: passMessage(message) }),
+};

src/matchers/pass/index.test.js

@@ -0,0 +1,21 @@
+import matcher from './';
+
+expect.extend(matcher);
+
+describe('.pass', () => {
+  test('passes without message', () => {
+    expect().pass();
+  });
+  test('passes with message', () => {
+    expect().pass('this should pass!');
+  });
+});
+
+describe('.not.pass', () => {
+  test('does not pass, has no message', () => {
+    expect(() => expect().not.pass()).toThrowErrorMatchingSnapshot();
+  });
+  test('does not.pass, has no message', () => {
+    expect(() => expect().not.pass('This should not pass!')).toThrowErrorMatchingSnapshot();
+  });
+});

src/matchers/pass/predicate.js

@@ -0,0 +1 @@
+export default () => true;

src/matchers/pass/predicate.test.js

@@ -0,0 +1,7 @@
+import predicate from './predicate';
+
+describe('true Predicate', () => {
+  test('returns true', () => {
+    expect(predicate()).toBe(true);
+  });
+});