为验证字符串输入编写参数化测试的最佳实践是什么？

Question

I'm writing a parameterized unit test for a code something similar to below, to make sure that my tests cover all the possible input cases and the system behaves as expected.

I came up with 3 approaches ie testGetAnimalMood1, testGetAnimalMood2, testGetAnimalMood3:

public class Exp {

    enum Animal{
        CAT("Cat is happy"),
        DOG("Dog is sad");

        Animal(String mood){
            this.mood = mood;
        }

        private String mood;

        public String getMood(){
            return this.mood;
        }
    }

    public static String getAnimalsMood(String animal){
        return Animal.valueOf(animal).getMood();
    }
}

public class ExpTest {

    @ParameterizedTest
    @CsvSource({"CAT, Cat is happy", "DOG, Dog is sad"})
    public void testGetAnimalMood1(String animal, String expected){
        String mood = Exp.getAnimalsMood(animal);

        Assertions.assertEquals(expected, mood);
    }

    @ParameterizedTest
    @MethodSource("getAnimalMoodParameters2")
    public void testGetAnimalMood2(String animal, String expected){
        String mood = Exp.getAnimalsMood(animal);

        Assertions.assertEquals(expected, mood);
    }

    public static Stream<Arguments> getAnimalMoodParameters2(){
        return Stream.of(Arguments.of("CAT", "Cat is happy"),Arguments.of("DOG", "Dog is sad"));
    }

    @ParameterizedTest
    @MethodSource("getAnimalMoodParameters3")
    public void testGetAnimalMood3(String animal, String expected){
        String mood = Exp.getAnimalsMood(animal);

        Assertions.assertEquals(expected, mood);
    }

    public static Stream<Arguments> getAnimalMoodParameters3(){
        return Arrays.stream(Exp.Animal.values()).map(e -> Arguments.of(e.name(), e.getMood()));
    }

}

testGetAnimalMood2 looks cleaner than testGetAnimalMood1 by using MethodSource. However at the same time it's harder to read which values are used to test than before. Thinking that there is not much value added by getAnimalMoodParameters2 method, which version is a better practice to use?

testGetAnimalMood3 looks even cleaner but it has the potential danger of validating my false logic as it's using a similar approach with the test under code to get the values. Also I might not be able catch possible typos if I do not write the values as strings. But a counter argument would be, another user trying to modify this code might not be able to understand the behavior by just looking at those arbitrary strings.

Thinking all those arguments or if you have to add more, which one is the best approach?

Answer 1

I use this setup when I'm writing parameterized tests:

@RunWith(Parameterized.class)
public class MyTest {
    @Parameter(0)
    public String animal;
    @Parameter(1)
    public String expected;

    @Parameters
    public static List<String[]> parameters() {
        return Arrays.asList(
            new String[]{"CAT", "Cat is happy"},
            new String[]{"DOG", "Dog is sad"}
        );
    }

    @Test
    public void testGetAnimalMood(){
        String mood = Exp.getAnimalsMood(animal);

        Assertions.assertEquals(expected, mood);
    }
}

@RunWith(Parameterized.class) tells JUnit to run your class with different parameters.

The static method annotated with @Parameters is your method source.

The two fields annotated with @Parameter tell JUnit which parameter at which index should be picked.

And the rest should be self explaining