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A way to provide the arguments "name" without actually having it as an argument. #2301

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A way to provide the arguments "name" without actually having it as an argument.#2301
#2521
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juliette-derancourt
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component: Jupitertheme: parameterized teststype: enhancement
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5.8 M1
@xenoterracide

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@xenoterracide
xenoterracide
opened on May 15, 2020 · edited by juliette-derancourt

So I have a parameterized test, and each parameter is a List of Beans where each bean represents a line in a csv file (opencsv). What I want for the actual "parameterized name" is the filename.

I'm thinking something like return

Arguments.of( Named.by(file.getName()), new ArrayList<>() );

@ParameterizedTest
@ArgumentsSource(MyArgumentsProvider.class)
void test( List<AlgorithmVerification> verifications )

Obviously the workaround is to simply pass it as the first parameter and include it as an unused argument. I just have a dislike of unused arguments.

@ParameterizedTest
@ArgumentsSource(MyArgumentsProvider.class)
void test( String filename, List<AlgorithmVerification> verifications )

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juliette-derancourt

juliette-derancourt commented on May 15, 2020

@juliette-derancourt
juliette-derancourt
on May 15, 2020
Member

I had the exact same use case not long ago, and I ended up passing the name as an argument like you did. I agree that it's not ideal...

That being said, I'm not sure how your solution whould deal with the name attribute of @ParameterizedTest? Would the name provided in Arguments replace it? Would you be able to insert it in the name with a placeholder like the other arguments?

juliette-derancourt
added
component: Jupiter
theme: parameterized tests
type: enhancement
on May 15, 2020
xenoterracide

xenoterracide commented on May 15, 2020

@xenoterracide
xenoterracide
on May 15, 2020
Author

I think in the proposed solution it would replace it, though you could also do that latter, I'm not certain on the right answer there. TBH I'm not even certain the proposed answer is the right answer.

juliette-derancourt

juliette-derancourt commented on May 15, 2020

@juliette-derancourt
juliette-derancourt
on May 15, 2020
Member

Personally I think I'd prefer the latter.
But I'm not sure it would be useful outside of this (pretty rare) use case... Unless you see other ones?

TBH I'm not even certain the proposed answer is the right answer.

Well I guess there is no right answer anyway 🤓

juliette-derancourt

juliette-derancourt commented on May 22, 2020

@juliette-derancourt
juliette-derancourt
on May 22, 2020
Member

I think the request in #1154 would also solve your problem, wouldn't it?

xenoterracide

xenoterracide commented on May 22, 2020

@xenoterracide
xenoterracide
on May 22, 2020 · edited by xenoterracide
Author

no, seems completely unrelated, since mine was about having to receive a parameter that I'm not using at all, other than to go into the test name. That would still be true even if the parser was improved. #1154 is still a great idea though. Thing is, in my example filename isn't in the array at all, it serves no real purpose other than to describe the file that I'm reading

xenoterracide

xenoterracide commented on May 22, 2020

@xenoterracide
xenoterracide
on May 22, 2020 · edited by xenoterracide
Author

Actually I might have described my proposed solution poorly, a better Api might be something like (obviously some pseudocode)

Arguments.of( Argument.of(filename, passAsArgument = false ))

then it wouldn't actually pass that first argument to the method signature, but it would still be passed to the description.

this is a pretty minor problem though.

marcphilipp

marcphilipp commented on Jun 8, 2020

@marcphilipp
marcphilipp
on Jun 8, 2020
Member

How about a simple Named<T> object that wraps the argument?

xenoterracide

xenoterracide commented on Jun 8, 2020

@xenoterracide
xenoterracide
on Jun 8, 2020
Author

personally not opposed

juliette-derancourt

juliette-derancourt commented on Jun 14, 2020

@juliette-derancourt
juliette-derancourt
on Jun 14, 2020
Member

How about a simple Named<T> object that wraps the argument?

I like the idea! 👍

sbrannen
mentioned this on Aug 6, 2020
sbrannen
added this to the 5.8 Backlog milestone on Aug 7, 2020
sbrannen

sbrannen commented on Aug 7, 2020

@sbrannen
sbrannen
on Aug 7, 2020
Member

Tentatively slated for 5.8 Backlog to be considered in conjunction with #2375.

5 remaining items

marcphilipp
added this to the 5.8 M1 milestone on Sep 25, 2020
marcphilipp

marcphilipp commented on Sep 25, 2020

@marcphilipp
marcphilipp
on Sep 25, 2020 · edited by marcphilipp
Member

Team decision: Add a Named<T> interface in junit-jupiter-api and add automatic support for injecting the contained payload into parameterized methods directly.

public interface Named<T> {
	static <T> Named<T> of(String name, T payload) {
		return new Named<T>() {
			@Override
			public String getName() {
				return name;
			}
			@Override
			public T getPayload() {
				return payload;
			}
			@Override
			public String toString() {
				return name;
			}
		};
	}
	String getName();
	T getPayload();
}
marcphilipp
removed
status: team discussion
on Sep 25, 2020
juliette-derancourt
self-assigned this
on Sep 27, 2020
juliette-derancourt
added
status: in progress
on Sep 27, 2020
thomasdarimont

thomasdarimont commented on Oct 2, 2020

@thomasdarimont
thomasdarimont
on Oct 2, 2020 · edited by thomasdarimont

This could be really useful when replicating Go style table-driven tests with DynamicTests and local records from Java 15.

import org.junit.jupiter.api.DynamicTest;
import org.junit.jupiter.api.TestFactory;

import java.util.stream.Stream;

import static org.junit.jupiter.api.Assertions.assertEquals;

class TableDrivenTest {

    @TestFactory
    Stream<DynamicTest> tableDrivenTestFromStream() {

        record TestCase(String name, int a, int b, int sum) {

            public void check() {
                assertEquals(sum, a + b, name);
            }
        }

        var testCases = Stream.of(
                new TestCase("test1", 1, 2, 3),
                new TestCase("test2", 2, 2, 4),
                new TestCase("test3", 4, 2, 6)
        );

        return DynamicTest.stream(testCases, TestCase::name, TestCase::check);
    }
}

See: https://twitter.com/thomasdarimont/status/1312100991127285760

With the Named interface from above, one could reduce the plumbing for this a bit.

Btw. if the DisplayName annotation were a bit more flexible one could do something like this:

...
        record TestCase(String name, int a, int b, int sum) {
            @Test
            @DisplayName("$name: $a + $b = $sum") 
            public void check() {
                assertEquals(sum, a + b, name);
            }
        }
...

Here is a gist with some more examples: https://gist.github.com/thomasdarimont/1650ab4d914072bb32d32b58a9ccc571

juliette-derancourt
mentioned this on Jan 9, 2021
juliette-derancourt
closed this as completedin #2521on Feb 8, 2021
juliette-derancourt
removed
status: in progress
on Feb 8, 2021
juliette-derancourt
removed their assignment
on Feb 8, 2021
sbrannen
assigned
juliette-derancourt
on Feb 11, 2021
FlorianCousin

FlorianCousin commented on Nov 19, 2021

@FlorianCousin
FlorianCousin
on Nov 19, 2021

What if we have several parameters in a test as follows ?

  @ParameterizedTest
  @ArgumentsSource(DataProvider.class)
  void test(String firstInput, String secondInput) {
    // A test
  }

For such a test, I would get my parameters as follows :

  Stream.of(arguments("first input", "second input"));

It seems that I cannot write

  Stream.of(arguments(Named.of("cool name", "first input", "second input")));

Is there any trick I missed ?

marcphilipp

marcphilipp commented on Nov 21, 2021

@marcphilipp
marcphilipp
on Nov 21, 2021
Member

Named allows you to override the name of one argument.

Hence, you could do

Stream.of(arguments(named("cool name", "first input"), "second input"));

and then use the name attribute in order to use that name to describe the entire invocation:

@ParameterizedTest(name = "{0}")
@ArgumentsSource(DataProvider.class)
void test(String firstInput, String secondInput) {
	// A test
}
FlorianCousin

FlorianCousin commented on Nov 21, 2021

@FlorianCousin
FlorianCousin
on Nov 21, 2021

I see, thank you @marcphilipp.

aws-gibbskt
mentioned this on May 15, 2024
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      A way to provide the arguments "name" without actually having it as an argument. · Issue #2301 · junit-team/junit-framework