JUnit 5 parameterized tests

Issue: BAEL-1665

testing-modules/junit-5/pom.xml

@@ -21,6 +21,11 @@
             <artifactId>junit-platform-engine</artifactId>
             <version>${junit.platform.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-params</artifactId>
+            <version>${junit.jupiter.version}</version>
+        </dependency>
         <dependency>
             <groupId>org.junit.platform</groupId>
             <artifactId>junit-platform-runner</artifactId>

testing-modules/junit-5/src/test/java/com/baeldung/parameterized/BlankStringsArgumentsProvider.java

@@ -0,0 +1,19 @@
+package com.baeldung.parameterized;
+
+import org.junit.jupiter.api.extension.ExtensionContext;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.ArgumentsProvider;
+
+import java.util.stream.Stream;
+
+class BlankStringsArgumentsProvider implements ArgumentsProvider {
+
+    @Override
+    public Stream<? extends Arguments> provideArguments(ExtensionContext context) {
+        return Stream.of(
+                Arguments.of((String) null),
+                Arguments.of(""),
+                Arguments.of("   ")
+        );
+    }
+}

testing-modules/junit-5/src/test/java/com/baeldung/parameterized/EnumsUnitTest.java

@@ -0,0 +1,50 @@
+package com.baeldung.parameterized;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+import org.junit.jupiter.params.provider.EnumSource;
+
+import java.time.Month;
+import java.util.EnumSet;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class EnumsUnitTest {
+
+    @ParameterizedTest
+    @EnumSource(Month.class)
+    void getValueForAMonth_IsAlwaysBetweenOneAndTwelve(Month month) {
+        int monthNumber = month.getValue();
+        assertTrue(monthNumber >= 1 && monthNumber <= 12);
+    }
+
+    @ParameterizedTest(name = "{index} {0} is 30 days long")
+    @EnumSource(value = Month.class, names = {"APRIL", "JUNE", "SEPTEMBER", "NOVEMBER"})
+    void someMonths_Are30DaysLong(Month month) {
+        final boolean isALeapYear = false;
+        assertEquals(30, month.length(isALeapYear));
+    }
+
+    @ParameterizedTest
+    @EnumSource(value = Month.class, names = {"APRIL", "JUNE", "SEPTEMBER", "NOVEMBER", "FEBRUARY"}, mode = EnumSource.Mode.EXCLUDE)
+    void exceptFourMonths_OthersAre31DaysLong(Month month) {
+        final boolean isALeapYear = false;
+        assertEquals(31, month.length(isALeapYear));
+    }
+
+    @ParameterizedTest
+    @EnumSource(value = Month.class, names = ".+BER", mode = EnumSource.Mode.MATCH_ANY)
+    void fourMonths_AreEndingWithBer(Month month) {
+        EnumSet<Month> months = EnumSet.of(Month.SEPTEMBER, Month.OCTOBER, Month.NOVEMBER, Month.DECEMBER);
+        assertTrue(months.contains(month));
+    }
+
+    @ParameterizedTest
+    @CsvSource({"APRIL", "JUNE", "SEPTEMBER", "NOVEMBER"})
+    void someMonths_Are30DaysLongCsv(Month month) {
+        final boolean isALeapYear = false;
+        assertEquals(30, month.length(isALeapYear));
+    }
+    
+}

testing-modules/junit-5/src/test/java/com/baeldung/parameterized/LocalDateUnitTest.java

@@ -0,0 +1,18 @@
+package com.baeldung.parameterized;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.converter.ConvertWith;
+import org.junit.jupiter.params.provider.CsvSource;
+
+import java.time.LocalDate;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class LocalDateUnitTest {
+
+    @ParameterizedTest
+    @CsvSource({"2018/12/25,2018", "2019/02/11,2019"})
+    void getYear_ShouldWorkAsExpected(@ConvertWith(SlashyDateConverter.class) LocalDate date, int expected) {
+        assertEquals(expected, date.getYear());
+    }
+}

testing-modules/junit-5/src/test/java/com/baeldung/parameterized/Numbers.java

@@ -0,0 +1,8 @@
+package com.baeldung.parameterized;
+
+public class Numbers {
+
+    public static boolean isOdd(int number) {
+        return number % 2 != 0;
+    }
+}

testing-modules/junit-5/src/test/java/com/baeldung/parameterized/NumbersUnitTest.java

@@ -0,0 +1,15 @@
+package com.baeldung.parameterized;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class NumbersUnitTest {
+
+    @ParameterizedTest
+    @ValueSource(ints = {1, 3, 5, -3, 15, Integer.MAX_VALUE})
+    void isOdd_ShouldReturnTrueForOddNumbers(int number) {
+        assertTrue(Numbers.isOdd(number));
+    }
+}

testing-modules/junit-5/src/test/java/com/baeldung/parameterized/Person.java

@@ -0,0 +1,20 @@
+package com.baeldung.parameterized;
+
+class Person {
+
+    private final String firstName;
+    private final String middleName;
+    private final String lastName;
+
+    public Person(String firstName, String middleName, String lastName) {
+        this.firstName = firstName;
+        this.middleName = middleName;
+        this.lastName = lastName;
+    }
+
+    public String fullName() {
+        if (middleName == null || middleName.trim().isEmpty()) return String.format("%s %s", firstName, lastName);
+
+        return String.format("%s %s %s", firstName, middleName, lastName);
+    }
+}

testing-modules/junit-5/src/test/java/com/baeldung/parameterized/PersonAggregator.java

@@ -0,0 +1,15 @@
+package com.baeldung.parameterized;
+
+import org.junit.jupiter.api.extension.ParameterContext;
+import org.junit.jupiter.params.aggregator.ArgumentsAccessor;
+import org.junit.jupiter.params.aggregator.ArgumentsAggregationException;
+import org.junit.jupiter.params.aggregator.ArgumentsAggregator;
+
+class PersonAggregator implements ArgumentsAggregator {
+
+    @Override
+    public Object aggregateArguments(ArgumentsAccessor accessor, ParameterContext context)
+            throws ArgumentsAggregationException {
+        return new Person(accessor.getString(1), accessor.getString(2), accessor.getString(3));
+    }
+}

testing-modules/junit-5/src/test/java/com/baeldung/parameterized/PersonUnitTest.java

@@ -0,0 +1,31 @@
+package com.baeldung.parameterized;
+
+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.provider.CsvSource;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class PersonUnitTest {
+
+    @ParameterizedTest
+    @CsvSource({"Isaac,,Newton, Isaac Newton", "Charles,Robert,Darwin,Charles Robert Darwin"})
+    void fullName_ShouldGenerateTheExpectedFullName(ArgumentsAccessor argumentsAccessor) {
+        String firstName = argumentsAccessor.getString(0);
+        String middleName = (String) argumentsAccessor.get(1);
+        String lastName = argumentsAccessor.get(2, String.class);
+        String expectedFullName = argumentsAccessor.getString(3);
+
+        Person person = new Person(firstName, middleName, lastName);
+        assertEquals(expectedFullName, person.fullName());
+    }
+
+    @ParameterizedTest
+    @CsvSource({"Isaac Newton,Isaac,,Newton", "Charles Robert Darwin,Charles,Robert,Darwin"})
+    void fullName_ShouldGenerateTheExpectedFullName(String expectedFullName,
+                                                    @AggregateWith(PersonAggregator.class) Person person) {
+
+        assertEquals(expectedFullName, person.fullName());
+    }
+}

testing-modules/junit-5/src/test/java/com/baeldung/parameterized/SlashyDateConverter.java

@@ -0,0 +1,27 @@
+package com.baeldung.parameterized;
+
+import org.junit.jupiter.api.extension.ParameterContext;
+import org.junit.jupiter.params.converter.ArgumentConversionException;
+import org.junit.jupiter.params.converter.ArgumentConverter;
+
+import java.time.LocalDate;
+
+class SlashyDateConverter implements ArgumentConverter {
+
+    @Override
+    public Object convert(Object source, ParameterContext context) throws ArgumentConversionException {
+        if (!(source instanceof String))
+            throw new IllegalArgumentException("The argument should be a string: " + source);
+
+        try {
+            String[] parts = ((String) source).split("/");
+            int year = Integer.parseInt(parts[0]);
+            int month = Integer.parseInt(parts[1]);
+            int day = Integer.parseInt(parts[2]);
+
+            return LocalDate.of(year, month, day);
+        } catch (Exception e) {
+            throw new IllegalArgumentException("Failed to convert", e);
+        }
+    }
+}

testing-modules/junit-5/src/test/java/com/baeldung/parameterized/StringParams.java

@@ -0,0 +1,10 @@
+package com.baeldung.parameterized;
+
+import java.util.stream.Stream;
+
+public class StringParams {
+
+    static Stream<String> blankStrings() {
+        return Stream.of(null, "", "  ");
+    }
+}

testing-modules/junit-5/src/test/java/com/baeldung/parameterized/Strings.java

@@ -0,0 +1,8 @@
+package com.baeldung.parameterized;
+
+class Strings {
+
+    static boolean isBlank(String input) {
+        return input == null || input.trim().isEmpty();
+    }
+}

testing-modules/junit-5/src/test/java/com/baeldung/parameterized/StringsUnitTest.java

@@ -0,0 +1,108 @@
+package com.baeldung.parameterized;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.*;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Stream;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class StringsUnitTest {
+
+    static Stream<Arguments> arguments = Stream.of(
+            Arguments.of(null, true), // null strings should be considered blank
+            Arguments.of("", true),
+            Arguments.of("  ", true),
+            Arguments.of("not blank", false)
+    );
+
+    @ParameterizedTest
+    @VariableSource("arguments")
+    void isBlank_ShouldReturnTrueForNullOrBlankStringsVariableSource(String input, boolean expected) {
+        assertEquals(expected, Strings.isBlank(input));
+    }
+
+    @ParameterizedTest
+    @ValueSource(strings = {"", "  "})
+    void isBlank_ShouldReturnTrueForNullOrBlankStrings(String input) {
+        assertTrue(Strings.isBlank(input));
+    }
+
+    @ParameterizedTest
+    @MethodSource("provideStringsForIsBlank")
+    void isBlank_ShouldReturnTrueForNullOrBlankStrings(String input, boolean expected) {
+        assertEquals(expected, Strings.isBlank(input));
+    }
+
+    @ParameterizedTest
+    @MethodSource // Please note method name is not provided
+    void isBlank_ShouldReturnTrueForNullOrBlankStringsOneArgument(String input) {
+        assertTrue(Strings.isBlank(input));
+    }
+
+    @ParameterizedTest
+    @MethodSource("com.baeldung.parameterized.StringParams#blankStrings")
+    void isBlank_ShouldReturnTrueForNullOrBlankStringsExternalSource(String input) {
+        assertTrue(Strings.isBlank(input));
+    }
+
+    @ParameterizedTest
+    @ArgumentsSource(BlankStringsArgumentsProvider.class)
+    void isBlank_ShouldReturnTrueForNullOrBlankStringsArgProvider(String input) {
+        assertTrue(Strings.isBlank(input));
+    }
+
+    private static Stream<String> isBlank_ShouldReturnTrueForNullOrBlankStringsOneArgument() {
+        return Stream.of(null, "", "  ");
+    }
+
+    @ParameterizedTest
+    @MethodSource("provideStringsForIsBlankList")
+    void isBlank_ShouldReturnTrueForNullOrBlankStringsList(String input, boolean expected) {
+        assertEquals(expected, Strings.isBlank(input));
+    }
+
+    @ParameterizedTest
+    @CsvSource({"test,TEST", "tEst,TEST", "Java,JAVA"}) // Passing a CSV pair per test execution
+    void toUpperCase_ShouldGenerateTheExpectedUppercaseValue(String input, String expected) {
+        String actualValue = input.toUpperCase();
+        assertEquals(expected, actualValue);
+    }
+
+    @ParameterizedTest
+    @CsvSource(value = {"test:test", "tEst:test", "Java:java"}, delimiter =':') // Using : as the column separator.
+    void toLowerCase_ShouldGenerateTheExpectedLowercaseValue(String input, String expected) {
+        String actualValue = input.toLowerCase();
+        assertEquals(expected, actualValue);
+    }
+
+    @ParameterizedTest
+    @CsvFileSource(resources = "/data.csv", numLinesToSkip = 1)
+    void toUpperCase_ShouldGenerateTheExpectedUppercaseValueCSVFile(String input, String expected) {
+        String actualValue = input.toUpperCase();
+        assertEquals(expected, actualValue);
+    }
+
+
+
+    private static Stream<Arguments> provideStringsForIsBlank() {
+        return Stream.of(
+                Arguments.of(null, true), // null strings should be considered blank
+                Arguments.of("", true),
+                Arguments.of("  ", true),
+                Arguments.of("not blank", false)
+        );
+    }
+
+    private static List<Arguments> provideStringsForIsBlankList() {
+        return Arrays.asList(
+                Arguments.of(null, true), // null strings should be considered blank
+                Arguments.of("", true),
+                Arguments.of("  ", true),
+                Arguments.of("not blank", false)
+        );
+    }
+}

testing-modules/junit-5/src/test/java/com/baeldung/parameterized/VariableArgumentsProvider.java

@@ -0,0 +1,45 @@
+package com.baeldung.parameterized;
+
+import org.junit.jupiter.api.extension.ExtensionContext;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.ArgumentsProvider;
+import org.junit.jupiter.params.support.AnnotationConsumer;
+
+import java.lang.reflect.Field;
+import java.util.stream.Stream;
+
+class VariableArgumentsProvider implements ArgumentsProvider, AnnotationConsumer<VariableSource> {
+
+    private String variableName;
+
+    @Override
+    public Stream<? extends Arguments> provideArguments(ExtensionContext context) {
+        return context.getTestClass()
+                .map(this::getField)
+                .map(this::getValue)
+                .orElseThrow(() -> new IllegalArgumentException("Failed to load test arguments"));
+    }
+
+    @Override
+    public void accept(VariableSource variableSource) {
+        variableName = variableSource.value();
+    }
+
+    private Field getField(Class<?> clazz) {
+        try {
+            return clazz.getDeclaredField(variableName);
+        } catch (Exception e) {
+            return null;
+        }
+    }
+
+    @SuppressWarnings("unchecked")
+    private Stream<Arguments> getValue(Field field) {
+        Object value = null;
+        try {
+            value = field.get(null);
+        } catch (Exception ignored) {}
+
+        return value == null ? null : (Stream<Arguments>) value;
+    }
+}

testing-modules/junit-5/src/test/java/com/baeldung/parameterized/VariableSource.java

@@ -0,0 +1,19 @@
+package com.baeldung.parameterized;
+
+import org.junit.jupiter.params.provider.ArgumentsSource;
+
+import java.lang.annotation.*;
+
+@Documented
+@Target(ElementType.METHOD)
+@Retention(RetentionPolicy.RUNTIME)
+@ArgumentsSource(VariableArgumentsProvider.class)
+public @interface VariableSource {
+
+    /**
+     * Represents the name of the static variable to load the test arguments from.
+     *
+     * @return Static variable name.
+     */
+    String value();
+}

testing-modules/junit-5/src/test/resources/data.csv

@@ -0,0 +1,4 @@
+input,expected
+test,TEST
+tEst,TEST
+Java,JAVA