Junit ParameterizedTest with expensive setup

Question

Im looking for a way of optimize running multiple parameterized tests with expensive setup

my current code looks like this

    @ParameterizedTest
    @MethodSource("test1CasesProvider")
    void test1(String param) {
        // expensive setup code 1
        
        // execution & assertions
    }

    @ParameterizedTest
    @MethodSource("test2CasesProvider")
    void test2(String param) {
        // expensive setup code 2
        
        // execution & assertions
    }

but in that shape expensive setup runs for every testCase, which is not very good I can split this test into two separate tests and use @BeforeAll, then setup runs only once per test, but im looking for a way to keep both cases in one test

Answer 1

You can use @Nested tests in this case, like this way:

public class MyTests {

    @Nested
    @TestInstance(TestInstance.Lifecycle.PER_CLASS)
    class Test1Cases {

        @BeforeAll
        void setUpForTest1() {
            System.out.println("Test1Cases: setting up things!");
        }

        @AfterAll
        void tearDownForTest1() {
            System.out.println("Test1Cases: tear down things!");
        }

        @ParameterizedTest
        @MethodSource("source")
        void shouldDoSomeTests(String testCase) {
            System.out.println("Test1Cases: Doing parametrized tests: " + testCase);
        }

        Stream<Arguments> source() {
            return Stream.of(
                Arguments.of("first source param!"),
                Arguments.of("second source param!"),
                Arguments.of("third source param!")
            );
        }
    }

    @Nested
    @TestInstance(TestInstance.Lifecycle.PER_CLASS)
    class Test2Cases {

        @BeforeAll
        void setUpForTest2() {
            System.out.println("Test2Cases: setting up things!");
        }

        @AfterAll
        void tearDownForTest2() {
            System.out.println("Test2Cases: tear down things!");
        }

        @ParameterizedTest
        @MethodSource("source")
        void shouldDoSomeTests(String testCase) {
            System.out.println("Test2Cases: Doing parametrized tests: " + testCase);
        }

        Stream<Arguments> source() {
            return Stream.of(
                Arguments.of("first source param!"),
                Arguments.of("second source param!"),
                Arguments.of("third source param!")
            );
        }
    }
}

The output in this case was:

Test2Cases: setting up things!
Test2Cases: Doing parametrized tests: first source param!
Test2Cases: Doing parametrized tests: second source param!
Test2Cases: Doing parametrized tests: third source param!
Test2Cases: tear down things!
Test1Cases: setting up things!
Test1Cases: Doing parametrized tests: first source param!
Test1Cases: Doing parametrized tests: second source param!
Test1Cases: Doing parametrized tests: third source param!
Test1Cases: tear down things!