[FIXED] Junit parametrize input and assertion

Issue

I have similiar tests when only input/assertion value differ:

@Test
void test1() {
    // Given:
    val request = Request
            .builder()
            .totalAmount(new BigDecimal("160000"))
            .termInYears(20)
            .familySize(2)
            .incomeAmount(new BigDecimal("4000"))
            .costOfLiving(BigDecimal.ZERO)
            .build();

    // When:
    Result result =
            facade.getLoanAmount(request);

    // Then:
    result.getSimulations().forEach(simulation -> {
        if(simulation.getVariantCode().equals(Variant.A)) {
            assertThat(simulation.getInstallmentAmount().compareTo(new BigDecimal("720")) == 0);
            assertThat(simulation.getInterestRate().compareTo(new BigDecimal("0.0321")) == 0);
            assertThat(simulation.getLoanAmount().compareTo(new BigDecimal("127390")) == 0);
            assertThat(simulation.getNumberOfInstallmentsInMonths() == 240);
        } if(simulation.getVariantCode().equals(Variant.B)) {
            assertThat(simulation.getInstallmentAmount().compareTo(new BigDecimal("720")) == 0);
            assertThat(simulation.getInterestRate().compareTo(new BigDecimal("0.0321")) == 0);
            assertThat(simulation.getLoanAmount().compareTo(new BigDecimal("127390")) == 0);
            assertThat(simulation.getNumberOfInstallmentsInMonths() == 240);
        } if(simulation.getVariantCode().equals(Variant.C)) {
            assertThat(simulation.getInstallmentAmount().compareTo(new BigDecimal("720")) == 0);
            assertThat(simulation.getInterestRate().compareTo(new BigDecimal("0.0321")) == 0);
            assertThat(simulation.getLoanAmount().compareTo(new BigDecimal("127390")) == 0);
            assertThat(simulation.getNumberOfInstallmentsInMonths() == 240);
        }
    });
}

@Test
void test2() {
    // Given:
    val request = Request
            .builder()
            .totalAmount(new BigDecimal("200000"))
            .termInYears(20)
            .familySize(2)
            .incomeAmount(new BigDecimal("4000"))
            .costOfLiving(BigDecimal.ZERO)
            .build();

    // When:
    Result result =
            facade.getLoanAmount(request);

    // Then:
    result.getSimulations().forEach(simulation -> {
        if(simulation.getVariantCode().equals(Variant.A)) {
            assertThat(simulation.getInstallmentAmount().compareTo(new BigDecimal("720")) == 0);
            assertThat(simulation.getInterestRate().compareTo(new BigDecimal("0.0321")) == 0);
            assertThat(simulation.getLoanAmount().compareTo(new BigDecimal("127390")) == 0);
            assertThat(simulation.getNumberOfInstallmentsInMonths() == 240);
        } if(simulation.getVariantCode().equals(Variant.B)) {
            assertThat(simulation.getInstallmentAmount().compareTo(new BigDecimal("720")) == 0);
            assertThat(simulation.getInterestRate().compareTo(new BigDecimal("0.0321")) == 0);
            assertThat(simulation.getLoanAmount().compareTo(new BigDecimal("127390")) == 0);
            assertThat(simulation.getNumberOfInstallmentsInMonths() == 240);
        } if(simulation.getVariantCode().equals(Variant.C)) {
            assertThat(simulation.getInstallmentAmount() == null);
            assertThat(simulation.getInterestRate() == null);
            assertThat(simulation.getLoanAmount()== null);
            assertThat(simulation.getNumberOfInstallmentsInMonths() == 240);
        }
    });
}

This code works fine but I wonder how to write this code nicier. I know that there is @ParameterizedTest but i'm not sure this will reduce line of code in this scenario and how to provide input/output there? What would be best approach? I have to write many more of tests like that so I think providing input/output for many tests would be nice. In Spock it would be a nice table but i have to use another tool.

Solution

If you're using JUnit 5 (ParameterizedTests in 4 are very different, but would also make it possible), something like this should work:

@ParameterizedTest
@MethodSource("arguments")
void test(Request input, BigDecimal result) {
 // ...
}

public static Stream<Arguments> arguments() {
    r1 = Request.builder().build(); // add request configuration here
    r2 = Request.builder().build(); // ... and here
    return Stream.of(
       Arguments.of(r1, new BigDecimal("720")),
       Arguments.of(r2, null)
    );
}

Answered By - OhleC
Answer Checked By - Pedro (JavaFixing Volunteer)