Junit5: Allow @ParameterizedTest declarations at type level for TCKs

[jkschneider]

Overview

Currently, the target of @ParameterizedTest is constrained to methods. When creating technology compatibility kits, it would be awesome to be able to apply this (or a similar annotation) to the test class so that all tests in that class are parameterized the same way.

Proposal

Rather than:

class MyTest {
   @ParameterizedTest
   @ArgumentSource(...)
   void feature1() { ... }

   @ParameterizedTest
   @ArgumentSource(...)
   void feature2() { ... }
}

Something like:

@ParameterizedTest
@ArgumentSource(...)
class MyTest {
   @Test // ?
   void feature1() { ... }

   @Test
   void feature2() { ... }
}

Related Issues

• #871
• #1141

[marcphilipp]

I can imagine supporting something like

@ArgumentSource(...)
class MyTest {
   @ParameterizedTest
   void feature1() { ... }

   @ParameterizedTest
   void feature2() { ... }
}

Would that suit your needs?

[jkschneider]

I think that is a good solution.

[nipafx]

Related issues: #871, #853

[jkschneider]

For real-life examples, see GaugeTest and most of the other tests in its package.

[marcphilipp]

@jkschneider Do you have time to work on a PR?

[smoyer64]

If a parameter source annotation is placed on an individual method in a type that's been annotated like this would it make sense for the more specific annotation to take precedence?

[jkschneider]

Yes as a matter of determinism? I think in practice, this would not be the way I'd recommend folks structure their test.

[wrlyonsjr]

Is this feature on the roadmap? I can't migrate to 5 without it.

[wrlyonsjr]

...unless someone knows of a workaround.

[jkschneider]

@wrlyonsjr I flipped it around with Micrometer's TCK by defining an abstract class with my test methods, each of which takes an implementation of MeterRegistry and for which there are many implementations. The RegistryResolver extension injects the implementation into each method at any nesting level.

Then there is a corresponding test for each implementation of MeterRegistry that extends this base class.

The approach has the disadvantage that you can't run the TCK abstract class from the IDE and execute the tests for all implementations, but this is the best I could do.

[wrlyonsjr]

It seems like my problem could be solved with TestTemplate et al.

[sbrannen]

Moved to 5.1 backlog due to repeated requests for a feature like this at conferences, etc.

[dmitry-timofeev]

Let me share my experience with parameterized tests in the new JUnit. Hope that helps to clarify the uses cases and requirements for Parameterized classes.

I think that this feature will be universally useful, not for TCK only. I see its ultimate goal in bringing down the cost of defining multiple tests sharing the same parameters source. Currently, the following code is duplicated:

• Annotations, specifying the source (e.g., @MethodSource).
• Formatting strings for parameters (e.g., "[{index}] = {3}").
• Initialization & Clean-up code, if any. If it has to initialize multiple _local_ variables (i.e., not extractable in a separate method as a whole), it has the highest cost in terms of LOCs.

Having to repeat that code _discourages_ the users to write short, focused tests. On top of that, if developers do have a luxury of copy-pasting that code, reviewers and maintainers have to read all of it.

As an alternative, I've tried a dynamic test for a simple use case (little setup code, no teardown), but got both a personal impression and some reviews from colleagues that it's "overcomplicated".

Uses cases

A perfect use case for this feature, in my opinion, is the following:

1. A user writes a couple of parameterized tests which share the same parameters source and setup code.
2. When there are too many of them, a user extracts these tests in a nested _parameterized_ class (ideally, an IDE inspection tells the user to do that).
   
   
   
   • Test method arguments become either constructor arguments, or injected with @Parameter (as in JUnit 4), or setup method (@BeforeEach) arguments.
   
   
   • Initialization code goes to the setup method. Any locals needed in tests become fields of the test class.
   
   
   • Clean-up code goes to the teardown method (@AfterEach).
   
   

[marcphilipp]

I think supporting something like @Parameter makes sense for fields and method parameters.

I'm out of ideas where you'd put formatting strings for parameters that are shared for all parameterized tests, though.

[dmitry-timofeev]

@marcphilipp , I can think of a class-level annotation with name attribute, or, if users need more flexibility, let them provide an instance method returning a test description + a method-level annotation, or a reference to the method in the class-level annotation (e.g., @Parameterized(name="#testDescription")).

If no one on the core team is planning to work on this issue soon, I may try to implement an MVP. I am new to the code base, and have a couple of questions about the requirements:

• Shall anything except @ParameterizedTest be supported in a class annotated with @ArgumentsSource (@Test, other @TestTemplates)? It might get tricky for one of the most compelling use cases for parameterized classes is extracting test template parameters to the fields, and if there is no extension to resolve the values of these fields, it won't work, will it?
• Shall the extension support a _product_ of primary parameters (defined at the class level) and secondary parameters (defined at the method level, as in the current implementation), like this:

@CsvSource(/* primary parameters, injected into constructor/BeforeEach/fields */)
class FooTest {

  /** Invoked for each parameter in the source specified at the class level */
  @ParameterizedTest
  void foo() { }

  /** 
   * Invoked for the cartesian product of parameters from 
   * the source specified at the class level 
   * and parameters from the source at the method level.
   */
  @ParameterizedTest
  @ValueSource(/* secondary parameters for #bar only */)
  void bar(int secondaryParameter) { }
}

?

[marcphilipp]

I can think of a class-level annotation with name attribute, or, if users need more flexibility, let them provide an instance method returning a test description + a method-level annotation, or a reference to the method in the class-level annotation (e.g., @Parameterized(name="#testDescription")).

Maybe. Let's postpone that part until we've had some more time to ponder it.

Shall anything except @ParameterizedTest be supported in a class annotated with @ArgumentsSource (@Test, other @TestTemplates)? It might get tricky for one of the most compelling use cases for parameterized classes is extracting test template parameters to the fields, and if there is no extension to resolve the values of these fields, it won't work, will it?

How about we annotate fields/method parameters with @Parameter(index=0, optional=true) (optional should be false by default) and inject null for non-parameterized tests?

Shall the extension support a _product_ of primary parameters (defined at the class level) and secondary parameters (defined at the method level, as in the current implementation)

I would expect that the arguments provided by the @ValueSource would be _appended_ to those provided by the @CsvSource in your example, just like when both annotations would be declared on the method.

[sbrannen]

Moved to 5.1 backlog due to repeated requests for a feature like this at conferences, etc.

Actually, the requests I've been hearing are for "parameterized test class" support, not for sharing the same parameters across methods.

In other words, I've been hearing requests to be able to execute all tests within a given test class multiple times with different sets of parameters. When compared to the existing "test template" abstraction, this new feature would rely on a new "test class template" abstraction.

Do people think we can address the issues discussed thus far in _this_ issue with such a "test class template" abstraction?

Or are these orthogonal concerns?

[marcphilipp]

I'm also wondering whether adding something like container templates (cf. #871) would be clearer. If we had those, we could introduce s.th. like @ParameterizedContainer:

@CsvSource(...)
@ParameterizedContainer(name = ...)
class SomeTestClass {

    @Parameter(0)
    private String foo;

    @Test
    void test() {
        ...
    }
}

[sbrannen]

Ahhh.... yes... #871 is what I was looking for!

[sbrannen]

I've added comments to #871 accordingly.

[dmitry-timofeev]

How about we annotate fields/method parameters with @Parameter(index=0, optional=true) (optional should be false by default) and inject null for non-parameterized tests?

Won't that be hard to explain to users and force them to write complicated setup/teardown code, if they have any?

I would expect that the arguments provided by the @ValueSource would be appended to those provided by the @CsvSource in your example, just like when both annotations would be declared on the method.

I see, perhaps, my example failed to convey that I expected different sets of parameters, e.g., @CsvSource({"John, Doe", "Mark, Twain") & @ValueSource(ints = 18, 45).

I think a "test class template" will certainly address the simple use case above, and, likely, clearer, because:

• It will give more flexibility for one can put anything in a "test class template":
  
  
  
  • Regular @Tests that will share both the class-level parameters and the setup/teardown code.
  
  
  • _Any_ @TestTemplates, to get a cartesian product of the sets of _class_ parameters, and the parameters of the @TestTemplate, as in example above.
  
  
• Resolvers of parameters of a "test class template" and of a "method template" will be independent, will operate on their own level of abstraction, and therefore, be simpler to write and maintain.
• It will yield a hierarchy of tests ("test class templates" -> "regular tests"/"test method templates") that is easier to understand and give names to than a flattened one.

With that much flexibility, "test class templates" are likely to satisfy both simple and advanced or niche uses cases.

[xenoterracide]

I think this might work for my use case #1456, but I'm not certain what the exact syntax would look like reading this issue.

[sbrannen]

but I'm not certain what the exact syntax would look like reading this issue.

Fret not: we also don't know what the syntax will look like. It's up for debate. 😉

[rlundy]

Would it help to have a concrete example to start from?

I'm using JUnit 4 for Selenium tests. I want to run them in multiple browsers. I'm using test class parameterization to do it.

As I have it set up now, a test looks like this:

public class TeamTest extends TestBase {
    public TeamTest(String browser) {
        super(browser);
    }

    @Test
    public void canCreateTeam() {
    // ...

TestBase looks like this:

@RunWith(Parameterized.class)
public abstract class TestBase {

    protected RemoteWebDriver driver;

    protected TestBase(String browser) {
        driver = new DriverCreator().getDriver(browser);
    }

    @Parameters(name = "{0}")
    public static Object[] data() {
        var browserString = Common.getString(Prop.browsers);
        return browserString.split(" *, *");
    }

    // ...

In TestBase, I parse the browser string (which ultimately comes from a configuration file) and then pass that to the test class constructor, which creates browser instances from it.

In each test class, all I have to do is inherit from TestBase and define the constructor. I don't have to decorate individual test methods at all (other than having @Test on them, of course). The test names come out as TeamTest.canCreateTeam[chrome], TeamTest.canCreateTeam[firefox], etc.

So, what might the syntax for this look like if it were added to JUnit 5?

[sbrannen]

So, what might the syntax for this look like if it were added to JUnit 5?

I think it could look very similar to what @marcphilipp proposed here: https://github.com/junit-team/junit5/issues/878#issuecomment-354544841

So, perhaps something like the following:

@ParameterizedContainer(name = "{0}")
@MethodSource("data")
public abstract class TestBase {

    @Parameter(0)
    private String browser;

    protected RemoteWebDriver driver;

    @BeforeEach
    void setUpDriver() {
        this.driver = new DriverCreator().getDriver(browser);
    }

    static Object[] data() {
        var browserString = Common.getString(Prop.browsers);
        return browserString.split(" *, *");
    }

    // ...
}

[lgoldstein]

My 2 cents: I like the flexibility that JUnit 5 provides in this context, but I think that the JUnit 4 parameterized tests paradigm still has a lot of value. The main use-case for it is this: have a test class that accepts the same parameter type/value for all tests. In other words, avoid copy/paste @ParameterizedTest annotation on each method since it is implied from the class-level capability.

@Parameterized
@ValuesSource(...whatever...)
public class FooTest {
    private final Foo testedValue;

    public FooTest(Foo testedValue) {
        this.testedValue = testedValue;
    }

    @Test
    public void testX() { .... }

    @Test
    public void testY() { .... }

    @Test
    public void testZ() { .... }

    ...etc... - no need to repeat @ParameterizedTest on each method -
}

[sbrannen]

@lgoldstein, isn't your @Parameterized proposal identical to the aforementioned @ParameterizedContainer proposal?

[lgoldstein]

Seems like it, a few more thing though

• the @Parameter annotation should be allowed on constructor parameter(s) as well
• If no @Parameter annotation present then behavior should be like JUnit 4 - i.e., vs. implicit positional parameters of the constructor

[marcphilipp]

@lgoldstein Thanks for your 2 cents! 😉

While I haven't made it explicit above, I agree that @ParameterizedContainer should support constructor injection in the same manner we currently support method injection for @ParameterizedTest.

[sbrannen]

@lgoldstein Thanks for your 2 cents! 😉

+1

While I haven't made it explicit above, I agree that @ParameterizedContainer should support constructor injection in the same manner we currently support method injection for @ParameterizedTest.

+1

[xenoterracide]

Yeah, my thought is that the Constructor should have an optional argument
supplier. So that you could have multiple arguments to the Constructor and
it runs for each set of those and then multiple even more for the methods
so you might end up with two sets of arguments for the Constructor and two
sets of arguments for a test method. Resulting in each test method being
executed four times. And of course you can see how this could expand to
many many times

On Tue, Jul 3, 2018, 9:31 AM Sam Brannen [e-mail] wrote:

@lgoldstein https://github.com/lgoldstein Thanks for your 2 cents! 😉

+1

While I haven't made it explicit above
https://github.com/junit-team/junit5/issues/878#issuecomment-354544841,
I agree that @ParameterizedContainer should support constructor injection
in the same manner we currently support method injection for
@ParameterizedTest.

+1

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[xenoterracide]

I've had a thought on this, and possibly one I should encode in another ticket...

Parameterized tests are nicer for running tests in functions; syntactically, and log wise. However... one of the problems I've had with tests in the past is with long tests. Imagine I want to test security for 3 different Roles, that have overlapping permissions, and this is a selenium test, each "parameter" (the role) takes 5 minutes to run. As far as I know there is no way to say run the 2nd argument on the command line (the possible ticket to open) and even if there was... how would this then impact that. I really like the idea of being able to specify my argument on the command line, even if it has to be positional. If anyone thinks discussing this as a feature (and how it would impact this) further, feel free to let me know.

[royteeuwen]

Has there been any solution provided for this yet? In experimental mode or whatever? I am migrating from junit4 to junit5 and we have loads of tests that use @RunWith(Parametrized) which are very hard to migrate at this moment without a lot of rework

[sbrannen]

Has there been any solution provided for this yet? In experimental mode or whatever?

The team is currently finishing up the 5.4 RC1 release with 5.4 GA to follow shortly thereafter.

This particular issue is scheduled for 5.5, likely to be implemented in conjunction with #871.

[tobiasdiez]

What is the current time plan for this feature (as it seems like it didn't make it into 5.5)

[marcphilipp]

@tobiasdiez We don't have a roadmap with hard deadlines. We really want to support this but there's always something more important to do. Thus, I'm afraid we cannot commit to a specific date other than soon™️.

[atnak]

FWIW, here's an extremely hack-slash workaround that uses @TestFactory as an intermediary:

@TestFactory
Stream<DynamicNode> testFooBar() throws Exception {
    return TestingUtils.parameterizedClassTester("foo={0} bar={1}", FooBar.class,
            Stream.of(Arguments.of(123, "abc"));
}

@lombok.RequiredArgsConstructor
static class FooBar {

    private final int foo;
    private final String bar;

    @BeforeEach
    void prepare() {
        ...
    }

    @Test
    void test1() {
        ...
    }

}

TestingUtils.parameterizedClassTester() implementation here.

• While it supports @Test, @BeforeEach and @AfterEach,
• It doesn't support @BeforeAll or @AfterAll. (Although @BeforeAll could be replaced by the constructor.)
• The class needs to be static. (Probably anything more robust is better suited with full-blown annotations)
• And it's a hack because:
  
  
  
  • It ignores most of the things in org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor
    
    such as features surrounding @BeforeEach and @AfterEach and handling of exception during callbacks
  
  
  • The use of MessageFormat to get the display name should be more like org.junit.jupiter.params.ParameterizedTestNameFormatter's implementation
  
  
  • Class instances shouldn't be leaking but it could be (I'm not certain)
  
  

[QIvan]

hi! Just wonder, any news about this in 2020?
Thanks.

[sbrannen]

hi! Just wonder, any news about this in 2020?

Please see https://github.com/junit-team/junit5/issues/878#issuecomment-546459081

[slyoldfox]

At the moment I am (ab)using(?) @Parameterized.Parameters to create Spring Boot Tests with all permutations of a set of profiles.

Each of the profiles exposes a certain set of configurations and beans and represents "a module".

This is very old code and I'm trying to tidy it up for Junit 5. Are there any prettier alternatives for this @sbrannen ? I looked at some Stackoverflow posts but none have a decent implementation (creating an Abstract class and putting each test seperately wasn't my preferred solution) for creating a sort of parametrized test for different spring boot profiles (maybe spring boot has some examples you know off?).

I am posting this here because it relied on constructor injection for the @Parameters and I'm not sure how else I could set the profile value to setup the TestContextManager.

@WebAppConfiguration
@ContextConfiguration(
        initializers = { SomeCustomMockServletContextInitializer.class}
)
@RunWith(Parameterized.class)
@ActiveProfiles(resolver = ITBootstrapWithAdditionalModules.CustomProfilesResolver.class)
public class ITBootstrapWithAdditionalModules
{
    private final String profile;

    private TestContextManager testContextManager;

    public ITBootstrapWithAdditionalModules( String profile
    ) {
        this.profile = profile;
    }

    @Parameterized.Parameters(name = "{index}: modules: {0}")
    public static Collection primeNumbers() {
        Set<Set<String>> powerset = Sets.powerSet( Sets.newHashSet( "with-ui", "with-data-store", "with-redis" ) );
        Object[] parameters = new Object[powerset.size()];
        final AtomicInteger i = new AtomicInteger();
        powerset.stream().forEach( item -> {
            parameters[i.get()] = new Object[] { StringUtils.join( item, "," ) };
            i.incrementAndGet();
        } );
        return Arrays.asList( parameters );
    }

    @Before
    public void setUpContext() throws Exception {
        System.setProperty( AbstractEnvironment.ACTIVE_PROFILES_PROPERTY_NAME, profile );
        this.testContextManager = new TestContextManager( getClass() );
        this.testContextManager.prepareTestInstance( this );
    }

    @After
    public void destroyContext() {
        testContextManager.getTestContext().markApplicationContextDirty(
                DirtiesContext.HierarchyMode.EXHAUSTIVE );
        testContextManager.getTestContext().setAttribute(
                DependencyInjectionTestExecutionListener.REINJECT_DEPENDENCIES_ATTRIBUTE, Boolean.TRUE );
        System.clearProperty( AbstractEnvironment.ACTIVE_PROFILES_PROPERTY_NAME );
    }

    @Test
    public void servicesShouldStartup() {
    }

    @Configuration
    protected static class Config
    {
        @Profile("with-ui")
        @Configuration
        public static class UiModuleProfile
        {
            @Bean
            public UiModule UiModule() {
                return new UiModule();
            }

            @Bean
            public BootstrapUiModule bootstrapUiModule() {
                return new BootstrapUiModule();
            }
        }

        @Profile("with-redis")
        @Configuration
        public static class RedisProfile
        {
            @Bean
            public RedisModule redisModule() {
                return new RedisModule();
            }
        }

        @Profile("with-datastore")
        @Configuration
        public static class DataStoreProfile 
        {
            @Bean
            public DataStoreModule dataStoreModule() {
                return new DataStoreModule();
            }
        }
    }

    static class CustomProfilesResolver implements ActiveProfilesResolver
    {
        public CustomProfilesResolver() {
        }

        @Override
        public String[] resolve( Class<?> testClass ) {
            return System.getProperty( AbstractEnvironment.ACTIVE_PROFILES_PROPERTY_NAME ).split( "," );
        }
    }
}