Add toBeValidDate matcher

Issue: jest-community#117

.all-contributorsrc

@@ -277,7 +277,9 @@
       "avatar_url": "https://avatars2.githubusercontent.com/u/980783?v=4",
       "profile": "http://foss-geek.blogspot.com/",
       "contributions": [
-        "code"
+        "code",
+        "test",
+        "doc"
       ]
     },
     {

README.md

@@ -53,6 +53,7 @@ If you've come here to help contribute - Thanks! Take a look at the [contributin
     * [.toBeFalse()](#tobefalse)
   * [Date](#date)
     * [.toBeDate()](#tobedate)
+    * [.toBeValidDate()](#tobevaliddate)
     * Further proposals in [#117](https://github.com/jest-community/jest-extended/issues/117) PRs welcome
   * [Function](#function)
     * [.toBeFunction()](#tobefunction)
@@ -332,6 +333,20 @@ test('passes when value is a date', () => {
 });
 ```
 
+### .toBeValidDate()
+
+Use `.toBeValidDate` when checking if a given `Date` object is valid.
+
+```
+test('passes when Date is valid', () => {
+  expect(new Date()).toBeValidDate();
+  expect('01/01/2018').not.toBeValidDate();
+  expect(new Date('01/01/2018').toBeValidDate();
+  expect(new Date('01/90/2018').not.toBeValidDate();
+  expect(undefined).not.toBeValidDate();
+});
+```
+
 ### Function
 
 #### .toBeFunction()

src/matchers/index.js

@@ -43,6 +43,7 @@ import toBeEmpty from './toBeEmpty';
 import toBeSealed from './toBeSealed';
 import toIncludeRepeated from './toIncludeRepeated';
 import toHaveBeenCalledBefore from './toHaveBeenCalledBefore';
+import toBeValidDate from './toBeValidDate';
 
 export default [
   toBeEven,
@@ -89,5 +90,6 @@ export default [
   toBeSealed,
   toSatisfy,
   toIncludeRepeated,
-  toHaveBeenCalledBefore
+  toHaveBeenCalledBefore,
+  toBeValidDate
 ].reduce((acc, matcher) => ({ ...acc, ...matcher }), {});

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

@@ -0,0 +1,3 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`.toBeValidDate fails when not given an invalid date 1`] = `"Invalid time value"`;

src/matchers/toBeValidDate/index.js

@@ -0,0 +1,26 @@
+import { matcherHint, printReceived } from 'jest-matcher-utils';
+
+import predicate from './predicate';
+
+const passMessage = received => () =>
+  matcherHint('.not.toBeValidDate', 'received', '') +
+  '\n\n' +
+  'Expected value to not be a valid date received:\n' +
+  `  ${printReceived(received)}`;
+
+const failMessage = received => () =>
+  matcherHint('.toBeValidDate', 'received', '') +
+  '\n\n' +
+  'Expected value to be a valid date received:\n' +
+  `  ${printReceived(received)}`;
+
+export default {
+  toBeValidDate: expected => {
+    const pass = predicate(expected);
+    if (pass) {
+      return { pass: true, message: passMessage(expected) };
+    }
+
+    return { pass: false, message: failMessage(expected) };
+  }
+};

src/matchers/toBeValidDate/index.test.js

@@ -0,0 +1,33 @@
+import each from 'jest-each';
+
+import matcher from './';
+
+expect.extend(matcher);
+
+describe('.toBeValidDate', () => {
+  test('passes when given a valid date', () => {
+    expect(new Date()).toBeValidDate();
+  });
+
+  test('fails when not given an invalid date', () => {
+    expect(() => expect(new Date('31/01/2018')).toBeValidDate()).toThrowErrorMatchingSnapshot();
+  });
+});
+
+describe('.not.toBeValidDate', () => {
+  each([
+    [new Date('01/90/2018')],
+    [new Date('32/01/2018')],
+    [false],
+    [true],
+    [0],
+    [''],
+    [{}],
+    [() => {}],
+    [undefined],
+    [null],
+    [NaN]
+  ]).test('passes when not given a date: %s', given => {
+    expect(given).not.toBeValidDate();
+  });
+});

src/matchers/toBeValidDate/predicate.js

@@ -0,0 +1,7 @@
+let is = type => value => Object.prototype.toString.call(value) === `[object ${type}]`;
+
+let hasDateType = is('Date');
+
+let isValidDate = value => hasDateType(value) && !isNaN(value) && !isNaN(value.getTime());
+
+export default expected => isValidDate(expected);

src/matchers/toBeValidDate/predicate.test.js

@@ -0,0 +1,24 @@
+import each from 'jest-each';
+import predicate from './predicate';
+
+describe('toBeDate Predicate', () => {
+  test('returns true when given a valid date', () => {
+    expect(predicate(new Date('12/25/2017'))).toBe(true);
+  });
+
+  each([
+    [new Date('01/90/2018')],
+    [new Date('32/01/2018')],
+    [true],
+    [false],
+    [''],
+    [0],
+    [{}],
+    [() => {}],
+    [undefined],
+    [null],
+    [NaN]
+  ]).test('returns false when given: %s', given => {
+    expect(predicate(given)).toBe(false);
+  });
+});