JUnit Basics

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

public class CalculatorTest {

    @Test
    void testAddition() {
        assertEquals(4, 2 + 2);
    }

    @Test
    void testSubtraction() {
        assertEquals(0, 2 - 2);
    }
}

Equality
assertEquals(expected, actual);
assertEquals(expected, actual, "message");

Boolean
assertTrue(condition);
assertFalse(condition);

Null checks
assertNull(object);
assertNotNull(object);

Same/Not same
assertSame(expected, actual);
assertNotSame(expected, actual);

Array equality
assertArrayEquals(expectedArray, actualArray);

import org.junit.jupiter.api.*;

public class TestLifecycle {

    @BeforeAll
    static void initAll() {
        // Runs once before all tests
    }

    @BeforeEach
    void init() {
        // Runs before each test
    }

    @AfterEach
    void tearDown() {
        // Runs after each test
    }

    @AfterAll
    static void tearDownAll() {
        // Runs once after all tests
    }
}

Disable test
@Disabled("Not implemented yet")
@Test
void testFeature() {}

Timeout
@Test
@Timeout(5)
void testWithTimeout() {}

Exception testing
@Test
void testException() {
    assertThrows(IllegalArgumentException.class, () -> {
        throw new IllegalArgumentException();
    });
}

Parameterized
@ParameterizedTest
@ValueSource(ints = {1, 2, 3})
void testNumbers(int number) {
    assertTrue(number > 0);
}