adinef/parameters-extended

A small extension to parameterized tests in JUnit 5.

JUnit 5 - parameters extended

By default, in JUnit 5, it is possible to inject parameters into a test method in different ways. This project extends the possibility in a very simple manner to introduce a new behavior.

Purpose

In JUnit 5, when a method annotated with @BeforeAll is used for creating objects used throughout the tests, the created instances need to be stored in static fields.

To encapsulate and remove possibility of side effect, where multiple tests may (for some reason) modify such variables, this project has been introduced.

Additionally, it adds functionality of named parameters.

Usage

To use extension, annotate your test class with:

@ExtendWith(ParamsExtended.class)
void TestClass { ... }

In set up method annotated with @Parameters.Setup, parameters can be set following way:

import org.junit.jupiter.api.BeforeAll;

@ExtendWith(ParamsExtended.class)
void TestClass {

    @Parameters.Setup
    private static void setUp(Parameters parameters) {
        parameters
                .add(new Integer(5))
                .addNamed("another", "Hello World!");
    }

    /* [...] */
}

Then, a test method can intercept the registered parameters:

import org.junit.jupiter.api.Test;

    /* [...] */
    @Test
    void test(Integer unnamed, @Named("another") String named) {/*[...]*/}
    /* [...] */

Test method can also directly get Parameters instance, however modification is only possible in a method annotated with @Parameters.Setup.

import org.junit.jupiter.api.Test;

    /* [...] */
    @Test
    void test2(Parameters parameters) {
        /*
        parameters.add(...) and parameters.addNamed(...) are not allowed,
        as instance injected into the test methods is read only.
        */

        final Integer unnamed = parameters.get(Integer.class);
        final String named = parameters.get("another");
    }
    /* [...] */