🗣️Fluent Assertions

How to assert Result objects fluently

You can use fluent assertions for Result objects to enhance the readability and expressiveness of your unit tests. These assertions are based on AssertJ, an open-source Java library that offers a fluent API for writing assertions in test cases.

AssertJ features a comprehensive and intuitive set of strongly-typed assertions for unit testing. It is a popular choice among Java developers due to its effective features and compatibility with various testing frameworks like JUnit and TestNG.

How to Use this Add-On

Add this Maven dependency to your build:

Group ID	Artifact ID	Latest Version
com.leakyabstractions	result-assertj

Maven Central provides snippets for different build tools to declare this dependency.

Asserting Result Objects

You can use ResultAssertions::assertThat in your tests to create fluent assertions for result objects.

import static com.leakyabstractions.result.assertj.ResultAssertions.assertThat;

@Test
void testAssertThat() {
  // Given
  final int zero = 0;
  // When
  final Result<Integer, String> result = success(zero);
  // Then
  assertThat(zero).isZero();
  assertThat(result).hasSuccess(zero);
}

If, for any reason, you cannot statically import assertThat, you can use ResultAssert::assertThatResult instead.

import static com.leakyabstractions.result.assertj.ResultAssert.assertThatResult;
import static org.assertj.core.api.Assertions.assertThat;

@Test
void testAssertThatResult() {
  // Given
  final int zero = 0;
  // When
  final Result<Integer, String> result = success(zero);
  // Then
  assertThat(zero).isZero();
  assertThatResult(result).hasSuccess(zero);
}

Conclusion

We covered how to use fluent assertions for Results. This approach allows you to write clear and expressive tests, enhancing the maintainability of your unit tests while ensuring that Result objects behave as expected.

The full source code for the examples is available on GitHub.