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Migrate to AssertJ from Hamcrest

In this tutorial, we'll use OpenRewrite to perform an automated migration from Hamcrest to AssertJ. AssertJ is more actively maintained than Hamcrest and is generally favored for testing assertions.

Configuration​

Configure your repository according to the instructions on the reference page. This is also where you'll find the full list of changes this recipe will make.

Before and After

Example test​

Before​

import org.junit.jupiter.api.Test;

import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.Matchers.equalTo;

public class BiscuitTest {
    @Test
    public void testEquals() {
        Biscuit theBiscuit = new Biscuit("Ginger");
        Biscuit myBiscuit = new Biscuit("Ginger");

        assertThat(theBiscuit, equalTo(myBiscuit));
        assertThat("chocolate chips", theBiscuit.getChocolateChipCount(), equalTo(10));
        assertThat("hazelnuts", theBiscuit.getHazelnutCount(), equalTo(3));
    }

    @Test
    public void otherExamples() {
        // ...

        assertThat(foo.get("id")).isEqualTo("test-data");
        assertThat(bar.size()).isEqualTo(1);
        assertThat(bash.get("one")).isEqualTo(1);
        assertThat(baz.size()).isEqualTo(concurrency * maxPerTask);
    }
}

After​

import org.junit.jupiter.api.Test;

import static org.assertj.core.api.Assertions.assertThat;

public class BiscuitTest {
    @Test
    public void testEquals() {
        Biscuit theBiscuit = new Biscuit("Ginger");
        Biscuit myBiscuit = new Biscuit("Ginger");

        assertThat(theBiscuit).isEqualTo(myBiscuit);
        assertThat(theBiscuit.getChocolateChipCount()).as("chocolate chips").isEqualTo(10);
        assertThat(theBiscuit.getHazelnutCount()).as("hazelnuts").isEqualTo(3);
    }

    @Test
    public void otherExamples() {
        // ...

        assertThat(foo).containsEntry("id", "test-data");
        assertThat(bar).hasSize(1);
        assertThat(bash).containsEntry("one", 1);
        assertThat(baz).hasSize(concurrency * maxPerTask);
    }
}

See how this recipe works across multiple open-source repositories​

Run this recipe on OSS repos at scale with the Moderne SaaS.

The community edition of the Moderne platform enables you to easily run recipes across thousands of open-source repositories.

Please contact Moderne for more information about safely running the recipes on your own codebase in a private SaaS.