Unit test an ASP.NET ApiController that uses the ApiController.Request property

gistfile1.txt

[TestMethod]
public void GetWithAnUnknownIdShouldReturnNotFound()
{
    // Arrange
    var controller = new BooksController()
    {
        Request = new HttpRequestMessage()
        {
            Properties = { { HttpPropertyKeys.HttpConfigurationKey, new HttpConfiguration() } }
        }
    };

    // Act
    var response = controller.Get(999);

    // Assert
    Assert.AreEqual(HttpStatusCode.NotFound, response.StatusCode);
}