ParameterResolver extension in JUnit - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to implement the ParameterResolver interface.

JUnit

public class MyParameterResolver implements ParameterResolver {
    @Override
    public boolean supportsParameter(ParameterContext parameterContext, ExtensionContext extensionContext) throws ParameterResolutionException {
        return parameterContext.getParameter().getType() == [1];
    }

    @Override
    public Object resolveParameter(ParameterContext parameterContext, ExtensionContext extensionContext) throws ParameterResolutionException {
        return "Hello, JUnit!";
    }
}

Drag options to blanks, or click blank then click option'

AObject.class

Bint.class

CList.class

DString.class

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong class type in supportsParameter.

Forgetting to use .class after the type.

The supportsParameter method should check if the parameter type is String.class to provide a String value.

2fill in blank

medium

Complete the test method to use the ParameterResolver extension.

JUnit

@ExtendWith(MyParameterResolver.class)
public class MyTest {
    @Test
    void testWithParameter([1] message) {
        assertEquals("Hello, JUnit!", message);
    }
}

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Aint

BList<String>

CString

DObject

Attempts:

3 left

💡 Hint

Common Mistakes

Using a parameter type not supported by the resolver.

Forgetting to annotate the test class with @ExtendWith.

The test method parameter must be String to match the ParameterResolver's supported type.

3fill in blank

hard

Fix the error in the supportsParameter method to correctly check for Integer type.

JUnit

@Override
public boolean supportsParameter(ParameterContext parameterContext, ExtensionContext extensionContext) {
    return parameterContext.getParameter().getType() == [1];
}

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AInteger.class

Bint.class

CLong.class

DDouble.class

Attempts:

3 left

💡 Hint

Common Mistakes

Using int.class instead of Integer.class.

Confusing primitive and wrapper types.

Use Integer.class to check for the Integer wrapper type, not int.class which is primitive.

4fill in blank

hard

Fill both blanks to correctly implement resolveParameter returning a fixed integer value.

JUnit

@Override
public Object resolveParameter(ParameterContext parameterContext, ExtensionContext extensionContext) {
    return [1];
}

@Override
public boolean supportsParameter(ParameterContext parameterContext, ExtensionContext extensionContext) {
    return parameterContext.getParameter().getType() == [2];
}

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A42

BString.class

CInteger.class

D100

Attempts:

3 left

💡 Hint

Common Mistakes

Returning a String instead of an Integer.

Checking for String.class instead of Integer.class.

The resolver returns 42 as an Integer, so supportsParameter must check for Integer.class.

5fill in blank

hard

Fill all three blanks to create a ParameterResolver that provides a List<String> with one element "test".

JUnit

public class ListParameterResolver implements ParameterResolver {
    @Override
    public boolean supportsParameter(ParameterContext parameterContext, ExtensionContext extensionContext) {
        return parameterContext.getParameter().getType() == [1];
    }

    @Override
    public Object resolveParameter(ParameterContext parameterContext, ExtensionContext extensionContext) {
        return [2];
    }
}

// Usage in test:
@ExtendWith(ListParameterResolver.class)
public class ListTest {
    @Test
    void testListParameter([3] list) {
        assertEquals(1, list.size());
        assertEquals("test", list.get(0));
    }
}

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AList.class

BList.of("test")

CList<String>

DArrayList.class

Attempts:

3 left

💡 Hint

Common Mistakes

Using ArrayList.class instead of List.class in supportsParameter.

Returning an empty list or wrong list content.

Using raw List instead of List in test method.

The supportsParameter checks for List.class, resolveParameter returns List.of("test"), and the test method parameter is List.