public void Should_return_the_composed_predicate() { // Arrange Predicate <QueryTestClass> p1 = delegate(QueryTestClass test) { return(test.Number == 5); }; Predicate <QueryTestClass> p2 = delegate(QueryTestClass test) { return(test.Number == 6); }; // Act var resultPredicate = queryBuilder.BuildAndPredicate(p1, p2); // Assert Assert.Equal(_testData.Count(x => x.Number == 5 && x.Number == 6), _testData.Count(x => resultPredicate(x))); }