Null Constraint

NullConstraint tests that a value is null. This is one of the most commonly used constraints for verifying that references have not been assigned or have been explicitly set to null.

Usage

Is.Null
Is.Not.Null

Examples

[Test]
public void NullConstraint_Examples()
{
    object? obj = null;
    Assert.That(obj, Is.Null);

    string name = "Alice";
    Assert.That(name, Is.Not.Null);

    // Combining with other constraints
    object? result = "value";
    Assert.That(result, Is.Not.Null.And.Not.EqualTo(""));
}

Notes

  1. For value types, consider using Is.Default instead, which tests for the default value of the type.
  2. When testing nullable value types (int?, bool?, etc.), Is.Null works as expected.

See Also