Generates data-driven Java unit tests using JUnit 5 @ParameterizedTest with @ValueSource, @CsvSource, @MethodSource for multiple inputs and boundary analysis.
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Provides patterns for parameterized unit tests in Java using JUnit 5. Covers @ValueSource, @CsvSource, @MethodSource, @EnumSource, @ArgumentsSource, and custom display names. Reduces test duplication by running the same test logic with multiple input values.
junit-jupiter-params is on test classpath (included in junit-jupiter)@ValueSource for simple values, @CsvSource for tabular data, @MethodSource for complex objectsname = "{0}..." for readable output./gradlew test --info or mvn test and verify all parameter combinations executeJUnit 5 parameterized tests require junit-jupiter (includes params). Add assertj-core for assertions:
<!-- Maven -->
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter</artifactId>
<scope>test</scope>
</dependency>
// Gradle
testImplementation("org.junit.jupiter:junit-jupiter")
@ValueSource — Simple Valuesimport org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.ValueSource;
import static org.assertj.core.api.Assertions.*;
@ParameterizedTest
@ValueSource(strings = {"hello", "world", "test"})
void shouldCapitalizeAllStrings(String input) {
assertThat(StringUtils.capitalize(input)).isNotEmpty();
}
@ParameterizedTest
@ValueSource(ints = {1, 2, 3, 4, 5})
void shouldBePositive(int number) {
assertThat(number).isPositive();
}
@ParameterizedTest
@ValueSource(ints = {Integer.MIN_VALUE, -1, 0, 1, Integer.MAX_VALUE})
void shouldHandleBoundaryValues(int value) {
assertThat(Math.incrementExact(value)).isGreaterThan(value);
}
@CsvSource — Tabular Dataimport org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.CsvSource;
@ParameterizedTest
@CsvSource({
"alice@example.com, true",
"bob@gmail.com, true",
"invalid-email, false",
"user@, false",
"@example.com, false"
})
void shouldValidateEmailAddresses(String email, boolean expected) {
assertThat(UserValidator.isValidEmail(email)).isEqualTo(expected);
}
@MethodSource — Complex Dataimport org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.MethodSource;
import java.util.stream.Stream;
@ParameterizedTest
@MethodSource("additionTestCases")
void shouldAddNumbersCorrectly(int a, int b, int expected) {
assertThat(Calculator.add(a, b)).isEqualTo(expected);
}
static Stream<Arguments> additionTestCases() {
return Stream.of(
Arguments.of(1, 2, 3),
Arguments.of(0, 0, 0),
Arguments.of(-1, 1, 0),
Arguments.of(100, 200, 300)
);
}
@EnumSource — Enum Values@ParameterizedTest
@EnumSource(Status.class)
void shouldHandleAllStatuses(Status status) {
assertThat(status).isNotNull();
}
@ParameterizedTest
@EnumSource(value = Status.class, names = {"ACTIVE", "INACTIVE"})
void shouldHandleSpecificStatuses(Status status) {
assertThat(status).isIn(Status.ACTIVE, Status.INACTIVE);
}
@ParameterizedTest(name = "Discount of {0}% should be calculated correctly")
@ValueSource(ints = {5, 10, 15, 20})
void shouldApplyDiscount(int discountPercent) {
double result = DiscountCalculator.apply(100.0, discountPercent);
assertThat(result).isEqualTo(100.0 * (1 - discountPercent / 100.0));
}
ArgumentsProviderclass RangeValidatorProvider implements ArgumentsProvider {
@Override
public Stream<? extends Arguments> provideArguments(ExtensionContext context) {
return Stream.of(
Arguments.of(0, 0, 100, true),
Arguments.of(50, 0, 100, true),
Arguments.of(-1, 0, 100, false),
Arguments.of(101, 0, 100, false)
);
}
}
@ParameterizedTest
@ArgumentsSource(RangeValidatorProvider.class)
void shouldValidateRange(int value, int min, int max, boolean expected) {
assertThat(RangeValidator.isInRange(value, min, max)).isEqualTo(expected);
}
@ParameterizedTest
@ValueSource(strings = {"", " ", null})
void shouldThrowExceptionForInvalidInput(String input) {
assertThatThrownBy(() -> Parser.parse(input))
.isInstanceOf(IllegalArgumentException.class);
}
name = "{0}..." for readable output@MethodSource for complex objects, @CsvSource for tabular data@ValueSource limitation: Only supports primitives, strings, and enums — not objects or null directly@CsvSource@MethodSource visibility: Factory methods must be static in the same test class{0}, {1}, etc. to reference parameters