JUnit 5 ParameterResolutionException: Mixing aggregation with direct binding

Question

I have the following JUnit parameterized test case which uses an aggregator as well as a directly bonded argument. When I run it, I get the following error: ParameterResolutionException: No ParameterResolver registered for parameter [java.lang.String arg1] in method [void PersonTest.testPersonGreeting(Person,java.lang.String)].

I think that JUnit can't know the index/column for the message argument because the PersonAggregator doesn't specify how many columns it uses. Is there a way to make this test work?

import org.junit.jupiter.api.extension.ParameterContext;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.aggregator.AggregateWith;
import org.junit.jupiter.params.aggregator.ArgumentsAccessor;
import org.junit.jupiter.params.aggregator.ArgumentsAggregator;
import org.junit.jupiter.params.provider.CsvSource;

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

class PersonTest {
    static class PersonAggregator implements ArgumentsAggregator {
        @Override
        public Person aggregateArguments(ArgumentsAccessor accessor, ParameterContext context) {
            return new Person(accessor.getString(0), accessor.getInteger(1));
        }
    }

    @ParameterizedTest
    @CsvSource({
            "Alice, 30, 'Hello Alice!'",
            "Bob, 40, 'Hello Bob!'"
    })
    void testPersonGreeting(@AggregateWith(PersonAggregator.class) Person person, String message) {
        assertEquals("Hello " + person.name() + "!", message);
    }
}

record Person(String name, int age) {}

Sercan Noyan Germiyanoğlu · Accepted Answer · 2024-11-16 15:16:13Z

0

Here is the solution shown below

To fix this issue, you can use a single ArgumentsAccessor to retrieve all the arguments

import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.aggregator.ArgumentsAccessor;
import org.junit.jupiter.params.provider.CsvSource;

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

class PersonTest {
    @ParameterizedTest
    @CsvSource({
            "Alice, 30, 'Hello Alice!'",
            "Bob, 40, 'Hello Bob!'"
    })
    void testPersonGreeting(ArgumentsAccessor accessor) {
        Person person = new Person(accessor.getString(0), accessor.getInteger(1));
        String message = accessor.getString(2);
        assertEquals("Hello " + person.name() + "!", message);
    }
}

record Person(String name, int age) {}

If you want to use an aggregator as custom, you should define another aggregator for string. Here is the code snippet for solution shown below

class PersonTest {
    
    // Aggregator for creating the Person object
    static class PersonAggregator implements ArgumentsAggregator {
        @Override
        public Person aggregateArguments(ArgumentsAccessor accessor, ParameterContext context) {
            return new Person(accessor.getString(0), accessor.getInteger(1));
        }
    }

    // Aggregator for extracting the message
    static class MessageAggregator implements ArgumentsAggregator {
        @Override
        public String aggregateArguments(ArgumentsAccessor accessor, ParameterContext context) {
            return accessor.getString(2);
        }
    }

    @ParameterizedTest
    @CsvSource({
            "Alice, 30, 'Hello Alice!'",
            "Bob, 40, 'Hello Bob!'"
    })
    void testPersonGreeting(
            @AggregateWith(PersonAggregator.class) Person person,
            @AggregateWith(MessageAggregator.class) String message) {
        assertEquals("Hello " + person.name() + "!", message);
    }
}

// Person record definition
record Person(String name, int age) {}

edited Nov 16, 2024 at 15:16

answered Nov 14, 2024 at 21:11

Sercan Noyan Germiyanoğlu

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2 Comments

Silas_229 Over a year ago

Thanks for your answer! Sure, this is possible, but I want the aggregator to create the Object. I could return a Pair<Person, String> by the aggregator or create a second aggregator for the message String, but it don't feels like an optimal solution, e. g. if the arguments differ in another test.

Sercan Noyan Germiyanoğlu Over a year ago

@Silas_229 I editted my post.

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