ClassCastException when using JUnit5 @ExtendWith and a customer ParameterResolver

Question

I am currently learning JUnit, and the nice new features it has. Specifically, I am working with a simple ParameterResolver, reproduced below

package com.junit.test.me.junit_testing;

import org.junit.jupiter.api.extension.ExtensionContext;
import org.junit.jupiter.api.extension.ParameterContext;
import org.junit.jupiter.api.extension.ParameterResolutionException;
import org.junit.jupiter.api.extension.ParameterResolver;

public class BankAccountParameterResolver implements ParameterResolver{

    @Override
    public boolean supportsParameter(ParameterContext parameterContext, ExtensionContext extensionContext)
            throws ParameterResolutionException {
        return parameterContext.getParameter().getType() == BankAccount.class;
    }

    @Override
    public Object resolveParameter(ParameterContext parameterContext, ExtensionContext extensionContext)
            throws ParameterResolutionException {
        return new BankAccount(0,0);
    }

}

However, when I go to use this ParameterResolver in my test (using the @ExtendsWith annotation), I get a strange ClassCastException

package com.junit.test.me.junit_testing;

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

import org.junit.jupiter.api.extension.ExtendWith;
import org.junit.jupiter.params.ParameterizedTest;

//This annotation gives the following error 
//Type mismatch: cannot convert from Class<BankAccountParameterResolver> to Class<? extends Extension>[]
@ExtendWith(BankAccountParameterResolver.class)
class BankAccountDITest {

    @ParameterizedTest
    public void testDeposit(BankAccount testMe) {
        testMe.deposit(500);
        assertEquals(500, testMe.getBalance());
    }
}

I think that somehow my project is importing two different JUnit versions, but I can't figure it out. My IDE is Eclipse, if that helps!

I tried following a simple online course for Junit 5, however I get a

ClassCastException

when I try to compile the test code. Any help would be appreciated, I've already tried restarting Eclipse and my machine, to no avail.

Answer 1

The problem was that somehow I had a BankAccountParameterResolver in a different location of my project. Once I made only one BankAccountParameterResolver exist, it worked fine.