What assertions does JUnit 6 provide and how do you use them?

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

class AssertionsDemo {

    @Test
    void basicAssertions() {
        assertEquals(4, 2 + 2);
        assertNotEquals(5, 2 + 2);
        assertTrue(4 > 3);
        assertFalse(4 < 3);
        assertNull(null);
        assertNotNull("hello");
    }

    @Test
    void assertionsWithMessages() {
        // Message is lazily evaluated (supplier) -- no cost if test passes
        assertEquals(4, 2 + 2, () -> "Expected 4 but was " + (2 + 2));
    }

    @Test
    void groupedAssertions() {
        // assertAll: ALL assertions run even if some fail
        // Reports ALL failures, not just the first one
        assertAll("address",
            () -> assertEquals("London",  address.city()),
            () -> assertEquals("UK",      address.country()),
            () -> assertEquals("EC1A 1BB", address.postcode())
        );
    }

    @Test
    void exceptionAssertions() {
        // assertThrows: passes only if the lambda throws the expected type
        Exception ex = assertThrows(IllegalArgumentException.class,
            () -> new Order(null, -1));
        assertEquals("Quantity must be positive", ex.getMessage());
    }

    @Test
    void doesNotThrow() {
        assertDoesNotThrow(() -> new Order("item", 1));
    }

    @Test
    void timeoutAssertions() {
        // Fails if the lambda takes longer than 1 second
        assertTimeout(Duration.ofSeconds(1), () -> Thread.sleep(500));
    }
}