How to use JUnit and Hamcrest together?

Question

I can\'t understand how JUnit 4.8 should work with Hamcrest matchers. There are some matchers defined inside junit-4.8.jar in org.hamcrest.CoreMatchers. At the

Answer 1

Not exactly answering your question, but you should definitely try FEST-Assert fluent assertions API. It's competing with Hamcrest, but has a much easier API with only one static import required. Here is the code provided by cpater using FEST:

package com.test;
import java.util.ArrayList;
import java.util.List;
import org.junit.Test;
import static org.fest.assertions.Assertions.assertThat;

public class EmptyTest {
    @Test
    public void testIsEmpty() {
        List myList = new ArrayList();
        assertThat(myList).isEmpty();
    }  
}

EDIT: Maven coordinates:

<dependency>
  <groupId>org.easytesting</groupId>
  <artifactId>fest-assert</artifactId>
  <version>1.4</version>
  <scope>test</scope>
</dependency>

Answer 2

If you're using a Hamcrest with a version greater or equal than 1.2, then you should use the junit-dep.jar. This jar has no Hamcrest classes and therefore you avoid classloading problems.

Since JUnit 4.11 the junit.jar itself has no Hamcrest classes. There is no need for junit-dep.jar anymore.

Answer 3

In 2018 using most modern libraries:

configurations {
    all {
        testCompile.exclude group: "org.hamcrest", module: "hamcrest-core"
        testCompile.exclude group: "org.hamcrest", module: "hamcrest-library"
    }
}
dependencies {
    testCompile("junit:junit:4.12")
    // testCompile("org.hamcrest:hamcrest-library:1.3")
    // testCompile("org.hamcrest:java-hamcrest:2.0.0.0")
    testCompile("org.hamcrest:hamcrest-junit:2.0.0.0")
}

Answer 4

why JUnit included org.hamcrest package into its own distribution instead of encouraging us to use original hamcrest library?

I would guess that's because they wanted the assertThat to be part of JUnit. So that means the Assert class has to import the org.hamcrest.Matcher interface and it can't do that unless JUnit either depends on Hamcrest, or includes (at least part of) Hamcrest. And I guess including part of it was easier, so that JUnit would be usable without any dependencies.

Answer 5

Since versions are changing all the time, I'm posting to let people know that as of December 2, 2014, the instructions at http://www.javacodegeeks.com/2014/03/how-to-test-dependencies-in-a-maven-project-junit-mockito-hamcrest-assertj.html worked for me. I did not use AssertJ though, just these:

<dependency>
  <groupId>junit</groupId>
  <artifactId>junit</artifactId>
  <version>4.11</version>
  <scope>test</scope>
</dependency>
<dependency>
  <groupId>org.mockito</groupId>
  <artifactId>mockito-core</artifactId>
  <version>1.9.5</version>
  <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.hamcrest</groupId>
    <artifactId>hamcrest-core</artifactId>
    <version>1.3</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.hamcrest</groupId>
    <artifactId>hamcrest-library</artifactId>
    <version>1.3</version>
    <scope>test</scope>
</dependency>   
<dependency>
    <groupId>org.objenesis</groupId>
    <artifactId>objenesis</artifactId>
    <version>1.3</version>
    <scope>test</scope>
</dependency>

Answer 6

Both JUnit-4.12 and JUnit-Dep-4.10 has Hamcrest dependencies according to the respective .xml files.

Further investigation shows that although the dependency was made in the .xml files, the source and classes in the jars. The seems to be a way of excluding the dependency in build.gradle ... testing it out to keep everything clean.

Just an f.y.i.