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Mocking Linq – Preview

Eli Lopian    Product    

We are working on our .NET 3.5 Support. There are many new feature that have been added, we will take a look at how to mock a linq statement

For the following code in our application

Northwind db = new Northwind(connStr) ;
var query = from c in db.Customers
where c.City == "Sarasota"
select new { c.Name, c.City };

Here is how to mock this statement and return fake customers

[TestMethod]
[VerifyMocks]
public void IsolateLinq()
{
// create fake return values
    var fake = new[] {
new {Name="Fake 1",City="NY"},
new {Name="Fake 2",City="London"}};

using (RecordExpectations r = new RecordExpectations())
{
// don't hit the database, instead return test customers
         Northwind db = new Northwind(connStr) ;
var answer = from c in db.Customers
where c.City == "not-used"
select new { c.Name, c.City };
r.Return(fake);
}
CallClassUnderTest();
// Continue with test
}

Comments about this syntax are welcome

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4 Comments to “Mocking Linq – Preview”

• 

  Larry-K December 31, 2007 at 7:31 am

  Can this Mocking Linq be done with the community version, or is a higher level required?
• 

  Eli Lopian December 31, 2007 at 9:00 am

  Larry,
  The Enterprise Edition is required for Linq.
• 

  Assaf Stone January 24, 2008 at 6:27 pm

  This is not true!

  Linq can be mocked with the community version.

  All you need to do is mock [Your]DataContext, and pass an IQueryable instead of your Table property (Use ExpectGetAlways(propertyName, mockList.AsQueryable()).

  HTH,
  Assaf.
• 

  lola March 6, 2008 at 8:12 pm

  interesting post thx