Hamcrest Date Matchers

Question

I need to test before/after on dates in a certain test case. I'd like to use Hamcrest matchers if possible.

Are there any matchers for Hamcrest (Java) for working with Dates? If so, what package/class would I find the particular date matcher functions in?

Solution 1

The OrderingComparison::greaterThan matcher will work on any type which is comparable to itself (it's in the org.hamcrest.number package, but it's not actually number-specific). Date is such a type.

Solution 2

There is a library of hamcrest date matchers provided by the library at https://github.com/eXparity/hamcrest-date which is also available for maven, ivy, etc at

<dependency>
    <groupId>org.exparity</groupId>
    <artifactId>hamcrest-date</artifactId>
    <version>1.1.0</version>
</dependency>

It supports various matchers for dates so allows constructs such as

Date myBirthday = new Date();
MatcherAssert.assertThat(myBirthday, DateMatchers.after(Moments.today()));

or

Date myBirthday = new Date();
MatcherAssert.assertThat(myBirthday, DateMatchers.isToday());

Solution 3

You can have a look at the new Date Matchers that will be added to hamcrest (I don't know when thought):

Date matchers discussion/code changes on github

After a quick look it seems there will be a new package org.hamcrest.date containing:

• IsAfter
• IsBefore
• IsSameDayOfTheMonth
• IsSameDayOfTheWeek
• IsSameDayOfTheYear
• IsSameHour
• IsSameInstant
• IsSameMinute
• IsSameMonth
• IsSameSecond
• IsSameYear
• IsWithin

Solution 4

There are certain hamcrest extensions that can ease some of the testing related to dates. Please check here.

Solution 5

The Matchers#greaterThan matcher works with Dates and other Comparable objects.

Here's the way to check that your date is greater than or equal (≥) to some expected date:

import static org.hamcrest.Matchers.equalTo;
import static org.hamcrest.Matchers.greaterThan;
import static org.hamcrest.core.AnyOf.anyOf;
...

Date expectedMin = new Date()
// Execute the method being tested
Date resultDate = getDate();
// Validate
assertThat(resultDate, anyOf(greaterThan(expectedMin), equalTo(expectedMin)))

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Comments

[Tom Anderson]

Thanks. It seems they've got rid of the class in favour of a static factory method, which makes a really stable link impossible, but i've fixed it as far as i can.

[JeanValjean]

That's true. There are also extensions that provide some more easy-to-read methods. E.g., Cirneco provides the matcher J7Matchers::after that is an alias for OrderingComparison::greaterThan. From my point of view, sematic is always important in unit test, that's why I usually prefer the fulent approach provided by Google Truth, but I sometimes have to handle with Hamcrest in legacy projects.

[Oleksandr Tarasenko]

How is this related to the topic?