Use Fakes to to unit test system or other assemblies not under your control.

Use Fakes to be able to unit test system or other assemblies not under your control.

[TestClass] public class TestClass1 { [TestMethod] public void TestCurrentYear() { int fixedYear = 2000; // Shims can be used only in a ShimsContext: using (ShimsContext.Create()) { // Arrange: // Shim DateTime.Now to return a fixed date: System.Fakes.ShimDateTime.NowGet = () => { return new DateTime(fixedYear, 1, 1); }; // Instantiate the component under test: var componentUnderTest = new MyComponent(); // Act: int year = componentUnderTest.GetTheCurrentYear(); // Assert: // This will always be true if the component is working: Assert.AreEqual(fixedYear, year); } } }