EntityFunctions.TruncateTime and unit tests

Question

I\'m using System.Data.Objects.EntityFunctions.TruncateTime method to get date part of a datetime in my query:

if (searchOptions.Date.HasValue)
         


        

Answer 1

I realize this is an old thread but wanted to post an answer anyways.

The following solution is done using Shims

I am not sure what versions (2013, 2012, 2010) and also flavors (express, pro, premium, ultimate) combinations of Visual Studio allow you to use Shims so it might be that this is not available to everyone.

Here is the code the OP posted

// some method that returns some testable result
public object ExecuteSomething(SearchOptions searchOptions)
{
   // some other preceding code 

    if (searchOptions.Date.HasValue)
        query = query.Where(c => 
            EntityFunctions.TruncateTime(c.Date) == searchOptions.Date);

   // some other stuff and then return some result
}

The following would be located in some unit test project and some unit test file. Here is the unit test that would use Shims.

// Here is the test method
public void ExecuteSomethingTest()
{
    // arrange
    var myClassInstance = new SomeClass();
    var searchOptions = new SearchOptions();

    using (ShimsContext.Create())
    {
        System.Data.Objects.Fakes.ShimEntityFunctions.TruncateTimeNullableOfDateTime = (dtToTruncate) 
            => dtToTruncate.HasValue ? (DateTime?)dtToTruncate.Value.Date : null;

        // act
        var result = myClassInstance.ExecuteSomething(searchOptions);
        // assert
        Assert.AreEqual(something,result);
     }
}

I believe this is probably the cleanest and most non-intrusive way to test code that makes use of EntityFunctions without generating that NotSupportedException.