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);
    }
}

Running this recipe with the Moderne CLI

You will need to have configured the Moderne CLI on your machine before you can run the following command:

shell

mod run . --recipe org.openrewrite.java.testing.assertj.Assertj

If the recipe is not available locally, then you can install it using:

shell

mod config recipes jar install org.openrewrite.recipe:rewrite-testing-frameworks:3.19.0

See how this recipe works across multiple open-source repositories

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Run this recipe here

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