Custom argument providers in JUnit - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a class that implements the ArgumentsProvider interface.

JUnit

public class MyArgumentsProvider implements [1] {
    @Override
    public Stream<? extends Arguments> provideArguments(ExtensionContext context) {
        return Stream.of(Arguments.of(1, 2), Arguments.of(3, 4));
    }
}

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AExtensionContext

BTest

CArgumentsSource

DArgumentsProvider

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Test annotation instead of implementing ArgumentsProvider.

Implementing the wrong interface like ArgumentsSource.

The class must implement the ArgumentsProvider interface to provide custom arguments for parameterized tests.

2fill in blank

medium

Complete the code to annotate a parameterized test method to use the custom argument provider.

JUnit

@ParameterizedTest
@[1](MyArgumentsProvider.class)
void testWithCustomProvider(int a, int b) {
    assertTrue(a < b);
}

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AValueSource

BCsvSource

CArgumentsSource

DTest

Attempts:

3 left

💡 Hint

Common Mistakes

Using @ValueSource or @CsvSource which are for built-in sources.

Using @Test instead of @ParameterizedTest.

The @ArgumentsSource annotation is used to specify a custom ArgumentsProvider class for parameterized tests.

3fill in blank

hard

Fix the error in the method signature to correctly override provideArguments.

JUnit

@Override
public Stream<? extends Arguments> [1](ExtensionContext context) {
    return Stream.of(Arguments.of("hello", 5));
}

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AprovideArguments

BprovideArgument

CgetArguments

DargumentsProvider

Attempts:

3 left

💡 Hint

Common Mistakes

Misspelling the method name as provideArgument or getArguments.

Using a different method name that does not override the interface.

The method to override in ArgumentsProvider is provideArguments with an 's' at the end.

4fill in blank

hard

Fill both blanks to create a stream of arguments with a string and an integer.

JUnit

return Stream.of(Arguments.of([1], [2]));

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A"JUnit"

B5

Ctrue

Dnull

Attempts:

3 left

💡 Hint

Common Mistakes

Using boolean or null instead of expected types.

Not quoting the string argument.

Arguments.of takes the values to pass to the test method. Here a string "JUnit" and integer 5 are correct.

5fill in blank

hard

Fill all three blanks to create a parameterized test with a custom argument provider and assert the sum.

JUnit

@ParameterizedTest
@ArgumentsSource([1].class)
void testSum(int x, int y) {
    int sum = x + y;
    assertEquals([2], sum);
}

public static class [3] implements ArgumentsProvider {
    @Override
    public Stream<? extends Arguments> provideArguments(ExtensionContext context) {
        return Stream.of(Arguments.of(2, 3), Arguments.of(4, 5));
    }
}

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ASumArgumentsProvider

B5

CMyArgumentsProvider

D7

Attempts:

3 left

💡 Hint

Common Mistakes

Mismatching class names between annotation and class.

Using wrong expected sum values in assertion.

The test uses MyArgumentsProvider as the source, asserts sum equals 5 for first pair, and the class name is MyArgumentsProvider.