assertj-arrow-core

This project provides a set of AssertJ assertions for the Arrow library. In detail, the project provides assertions for the following Arrow types:

• Either<E, A>
• Option<A>
• Raise<E>.() -> A
• NonEmptyList<A>

Maybe you're asking yourself: "Why do we need AssertJ assertions for Arrow types?". The answer is simple: We often use Kotlin and Arrow Kt inside a Java project using Spring Boot. In this case, we already have AssertJ in the classpath as an assertion library. So, why not use it to assert Arrow types?

Usage

The library is available on Maven Central. To use it, add the following dependency to your pom.xml file:

<dependency>
    <groupId>in.rcard</groupId>
    <artifactId>assertj-arrow-core</artifactId>
    <version>1.2.0</version>
    <scope>test</scope>
</dependency>

Otherwise, if you're using Gradle, add the following dependency to your build.gradle.kts file:

testImplementation("in.rcard:assertj-arrow-core:1.2.0")

Assertions Guide

This section describes the assertions provided by the assertj-arrow-core library.

Option<A>

Use the in.rcard.assertj.arrowcore.OptionAssert class as an entry point to assert Option<A> instances.

Assertions	Description
isEmpty	Verifies that the actual Option is empty.
contains	Verifies that the actual Option contains the given value.
containsInstanceOf	Verifies that the actual Option contains a value that is an instance of the argument.
get	Verifies that the actual Option is not null and not empty and returns an Object assertion that allows chaining (object) assertions on the optional value.
isDefined	Verifies that there is a value present in the actual Option.

Either<E, A>

Use the in.rcard.assertj.arrowcore.EitherAssert class as an entry point to assert Either<E, A> instances.

Assertions	Description
isRight	Verifies that the actual Either is right.
isLeft	Verifies that the actual Either is left.
containsOnRight	Verifies that the actual Either is Either.Right and contains the given value.
containsRightInstanceOf	Verifies that the actual right-sided Either contains a value that is an instance of the argument.
asRight	Verifies that the actual Either is not null and contains a right-sided value and returns an Object assertion that allows chaining (object) assertions on the value.
containsOnLeft	Verifies that the actual Either is Either.Left and contains the given value.
containsLeftInstanceOf	Verifies that the actual left-sided Either contains a value that is an instance of the argument.
asLeft	Verifies that the actual Either is not null and contains a left-sided value and returns an Object assertion that allows chaining (object) assertions on the value.

Raise<E>.() -> A

Use the in.rcard.assertj.arrowcore.RaiseAssert class as an entry point to assert Raise<E>.() -> A instances. There are many different entry points, all of them available boh for regular and suspend functions:

Entry Point	Description
assertThat	Entry point to assert a Raise<E>.() -> A instance.
assertThatThrownBy	Verifies that the function in the Raise context throws an exception and let chaining assertion on the thrown exception
assertThatRaisedBy	Verifies that the function in the Raise context raises a logic-typed error and let chaining assertion on the raised error

The available assertions are:

Assertions	Description
succeedsWith	Verifies that the function in the Raise context succeeds with the given value.
succeeds	Verifies that the function in the Raise context succeeded. No check on the value returned by the function is performed.
raises	Verifies that the function in the Raise context fails with the given error.
fails	Verifies that the function in the Raise context fails, no matter the type of the logical error.
result	Verifies that the actual function in the Raise context succeeds and returns an Object assertion that allows chaining (object) assertions on the returned value.
error	Verifies that the actual function in the Raise context fails and returns an Object assertion that allows chaining (object) assertions on the raised error.

NonEmptyList<A>

Use the in.rcard.assertj.arrowcore.NonEmptyListAssert class as an entry point to assert NonEmptyList<A> instances.

Assertions	Description
shouldContain	Verifies that the actual NonEmptyList contains the expected element.
shouldContainAll	Verifies that the actual NonEmptyList contains all the expected elements.
shouldContainNoNulls	Verifies that the actual NonEmptyList does not contain null.
shouldContainOnlyNulls	Verifies that the actual NonEmptyList contains only null.
shouldContainNull	Verifies that the actual NonEmptyList contains null.
shouldHaveDuplicates	Verifies that the actual NonEmptyList contains at least one duplicate.
shouldBeSingleElement	Verifies that the actual NonEmptyList has a single element which is expected element.
shouldBeSorted	Verifies that the actual NonEmptyList is sorted.