`DisplayNameGenerator` cannot access runtime enclosing type for `@Nested` test class

[sbrannen]

Overview

A DisplayNameGenerator can access the type of a @Nested test class as well as the enclosing class in which a @Nested test class is declared, but it cannot access the concrete runtime type of the enclosing instance for a @Nested test class.

When a DisplayNameGenerator is used to build hierarchical display names, this can lead to confusing results or even conflicting results depending on the structure of the test classes used, "conflicting" in the sense that two nested test classes may have identical display names that do not represent the runtime structure of the test classes.

Example

@IndicativeSentencesGeneration
abstract class AbstractBaseTests {

	@Nested
	class NestedTests {

		@Test
		void test() {
		}
	}
}

class ScenarioOneTests extends AbstractBaseTests {
}

class ScenarioTwoTests extends AbstractBaseTests {
}

Actual Behavior

When running ScenarioOneTests and ScenarioTwoTests, we currently see the following display names.

• ScenarioOneTests
  • AbstractBaseTests, NestedTests
    • AbstractBaseTests, NestedTests, test()
• ScenarioTwoTests
  • AbstractBaseTests, NestedTests
    • AbstractBaseTests, NestedTests, test()

Expected Behavior

When running ScenarioOneTests and ScenarioTwoTests, we would expect the following display names.

• ScenarioOneTests
  • ScenarioOneTests, NestedTests
    • ScenarioOneTests, NestedTests, test()
• ScenarioTwoTests
  • ScenarioTwoTests, NestedTests
    • ScenarioTwoTests, NestedTests, test()

Related Issues

• @DisplayNameGeneration is not discovered on runtime enclosing type for @Nested test class #4131

Deliverables

• Ensure that a DisplayNameGenerator can access the concrete runtime type of the enclosing instance for a @Nested test class.

[marcphilipp]

Team decision: Change DisplayNameGenerator as follows:

@Deprecated
default String generateDisplayNameForNestedClass(Class<?> nestedClass) {
	throw new UnsupportedOperationException("Implement generateDisplayNameForNestedClass(List<Class<?>>, Class<?>) instead")
}

default String generateDisplayNameForNestedClass(List<Class<?>> enclosingInstanceTypes, Class<?> nestedClass) {
	return generateDisplayNameForNestedClass(nestedClass);
}

@Deprecated
default String generateDisplayNameForMethod(Class<?> testClass, Method testMethod) {
	throw new UnsupportedOperationException("Implement generateDisplayNameForMethod(List<Class<?>>, Class<?>, Method) instead");
}

default String generateDisplayNameForMethod(List<Class<?>> enclosingInstanceTypes, Class<?> testClass,
		Method testMethod) {
	return generateDisplayNameForMethod(testClass, testMethod);
}

In addition, the actual instance types need to be collected via the parent TestDescriptors and the new methods should be called instead of the old ones.

[neronsoda]

Hi, can I work on this issue? :)

[marcphilipp]

@neronsoda Yes, please go ahead! 👍