TIL: @NullAndEmptySource in JUnit5

#junit5 #testing #todayilearned

This is a clear case of RTFM!

I wanted to make sure that a function will return null when given a null or empty string and what I ended up doing was something like this:

	internal class CreateNameTest {

	@ParameterizedTest
	@ValueSource(strings = ["null", "", " "])
	fun `there is no creation when the provided value is null or empty or blank`(providedValue: String?) {
	val value: String? = if (providedValue == "null")
	null else
	providedValue
	assertThat(createName(value), absent())
	}
	}

view raw initial_parameterized_test.kt hosted with ❤ by GitHub

@ValueSource does not accept null values so I passed it indirectly!

I didn’t like it so after, finally, reading the JUnit5 documentation I learned that the library had me covered from the beginning by providing three annotations exactly for this use case:

@NullSource, @EmptySource and @NullOrEmptySource are meant to be used whenever we need to check the behavior of our code when given null or empty inputs.

So the test changes to:

	internal class CreateNameTest {

	@ParameterizedTest
	@NullAndEmptySource
	@ValueSource(strings = [" "])
	fun `there is no creation when the provided value is null or empty or blank`(providedValue: String?) {
	assertThat(createName(providedValue), absent())
	}
	}