Uses for static generic classes?

Question

What are the key uses of a Static Generic Class in C#? When should they be used? What examples best illustrate their usage?

e.g.

Answer 1

I use these to mock a DbSet when testing against classes that use EntityFramework Async methods.

public static class DatabaseMockSetProvider where TEntity: class
{
    public static DbSet CreateMockedDbSet(IQueryable mockData)
    {
        var mockSet = Mock.Create>();
        Mock.Arrange(() => ((IDbAsyncEnumerable)mockSet).GetAsyncEnumerator())
            .Returns(new TestDbAsyncEnumerator(mockData.GetEnumerator()));
        Mock.Arrange(() => ((IQueryable)mockSet).Provider)
            .Returns(new TestDbAsyncQueryProvider(mockData.Provider));
        Mock.Arrange(() => ((IQueryable)mockSet).Expression).Returns(mockData.Expression);
        Mock.Arrange(() => ((IQueryable)mockSet).ElementType).Returns(mockData.ElementType);
        Mock.Arrange(() => ((IQueryable)mockSet).GetEnumerator()).Returns(mockData.GetEnumerator());

        return mockSet;
    }
}

And use them like so in my unit tests - saves a lot of time and can use them for any entity types:

var mockSet = DatabaseMockSetProvider.CreateMockedDbSet(recipes);
        Mock.Arrange(() => context.RecipeEntities).ReturnsCollection(mockSet);