ExactType Constraint

ExactTypeConstraint tests that an object is exactly the specified type, not a derived type.

Usage

Is.TypeOf(Type expectedType)
Is.TypeOf<T>()

Examples

[Test]
public void ExactTypeConstraint_Examples()
{
    // Exact type match
    Assert.That("Hello", Is.TypeOf(typeof(string)));
    Assert.That("Hello", Is.TypeOf<string>());
    Assert.That(42, Is.TypeOf<int>());

    // Derived types fail - exact match required
    Assert.That("Hello", Is.Not.TypeOf<object>());         // string is not exactly object
    Assert.That(new List<int>(), Is.TypeOf<List<int>>());
    Assert.That(new List<int>(), Is.Not.TypeOf<IList<int>>()); // List<int> is not exactly IList<int>

    // Common use: distinguish between value types
    Assert.That(42, Is.TypeOf<int>());
    Assert.That(42L, Is.TypeOf<long>());
    Assert.That(42L, Is.Not.TypeOf<int>());
}

Notes

  1. Is.TypeOf<T>() checks that actual.GetType() == typeof(T).
  2. For inheritance-aware type checking (like C# is), use InstanceOfTypeConstraint.
  3. null values throw an exception since they have no type.

See Also