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JUnit 6 - Expressing Nullability In Assertion Params

[Last Updated: Dec 1, 2025]

Starting version 6.0.0, JUnit Jupiter, started using JSpecify annotation to express nullability.

The following methods parameters of Assertions class which are now annotated with @Nullable, are allowed to accept null values.

fail()

public static <V> V fail(@Nullable String message)
public static <V> V fail(@Nullable String message, @Nullable Throwable cause)
public static <V> V fail(@Nullable Throwable cause)
public static <V> V fail(Supplier<@Nullable String> messageSupplier)

assertTrue()

public static void assertTrue(boolean condition, Supplier<@Nullable String> messageSupplier)
public static void assertTrue(BooleanSupplier booleanSupplier, @Nullable String message)
public static void assertTrue(boolean condition, @Nullable String message)
public static void assertTrue(BooleanSupplier booleanSupplier, Supplier<@Nullable String> messageSupplier)

assertFalse()

public static void assertFalse(boolean condition, @Nullable String message)
public static void assertFalse(boolean condition, Supplier<@Nullable String> messageSupplier)
public static void assertFalse(BooleanSupplier booleanSupplier, @Nullable String message)
public static void assertFalse(BooleanSupplier booleanSupplier, Supplier<@Nullable String> messageSupplier)

assertNull()

public static void assertNull(@Nullable Object actual)
public static void assertNull(@Nullable Object actual, @Nullable String message)
public static void assertNull(@Nullable Object actual, Supplier<@Nullable String> messageSupplier)

assertNotNull()

public static void assertNotNull(@Nullable Object actual)
public static void assertNotNull(@Nullable Object actual, @Nullable String message)
public static void assertNotNull(@Nullable Object actual, Supplier<@Nullable String> messageSupplier)

assertEquals() - Short

public static void assertEquals(short expected, @Nullable Short actual)
public static void assertEquals(@Nullable Short expected, short actual)
public static void assertEquals(@Nullable Short expected, @Nullable Short actual)
public static void assertEquals(short expected, @Nullable Short actual, @Nullable String message)
public static void assertEquals(@Nullable Short expected, short actual, @Nullable String message)
public static void assertEquals(@Nullable Short expected, @Nullable Short actual, @Nullable String message)
public static void assertEquals(short expected, @Nullable Short actual, Supplier<@Nullable String> messageSupplier)

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