泛型-如何将Lambda表达式传递给方法？

Question

I have a number of business service classes that I'm setting up unit tests for.

In mocking the data, I've got a fairly generic set of methods. One to provide a mocked dbSet, one to provide a service.

One thing I haven't managed to make generic as yet is the process of mocking the data context.

Right now I have something like:

mockDbSet = MyHelper.GetMockedDbSet(myData); // myData is an IQueryable List <T>
mockContext = new Mock<MyDataContext>();
// A handful of general .Setup lines snipped here
mockContext.Setup(m => m.Person).Returns(mockDbSet.Object);

Every unit test fixture is the same except for the last line, which the

m => m.Person

is substituted for some other entity.

All entities share the same base classes.

What I'm after is something like this:

mockContext = MyHelper.GetMockedDbContext(m => m.Person);

and be able to put all this generic code into the helper class.

I can't work out how to implement GetMockedDbContext , though.

Here's what I've got so far:

public static Mock<MyDataContext> GetMockedDbContext(Func<MyDataContext, object> func)
{
    var context = new Mock<MyDataContext>();

    // Now what?

    return context;
}

UPDATE: Here's what I've ended up doing so far. Something like this was posted as an answer, and then deleted. It seems to work.

public static Mock<MyDataContext> GetMockedDbContext<TResult>(Expression<Func<MyDataContext, TResult>> func, TResult result)
{
    var context = new Mock<MyDataContext>();
    // Snipped out stuff
    context.Setup(func).Returns(result);
    return context;
}

Answer 1

Your method's parameter should be of the same type as Setup method's parameter is, which means your method has to be generic too:

public static Mock<MyDataContext> GetMockedDbContext<T>(Expression<Func<MyDataContext, T>> func)
{
    var context = new Mock<MyDataContext>();

    // Now what?
    context.Setup(func).Returns(mockDbSet.Object);

    return context;
}