Constraints are a way to verify that a method's arguments match a certain criteria. Rhino Mocks includes a number of built-in constraints, and allows you to define you own custom ones, which will integrate cleanly into the framework. You specify constraints on method arguments using the following syntax:
Expect.Call(view.Ask(null,null)).IgnoreArguments().Constraints(
Is.Anything(), Is.TypeOf(typeof(SomeType))).Return(null).
You need to pass the exact same number of constraints as the number of arguments of the method. When a method is called during replay state, Rhino Mocks evaluates each constraint against the parameter in the same index, and accepts the method if all the constraints were met. As a note, I got the idea of the current constraints syntax from NMock2, as it is much leaner approach to create constraints.
Rhino Mocks' built in constraints:
Rhino Mocks Constraints
Constraint | Example | Accepted Values | Rejected Values | |
|---|---|---|---|---|
| Is | Anything | Is.Anything() | Anything at all {0,"","whatever",null, etc} | Nothing Whatsoever |
| Equal | Is.Equal(3) | 3 | 5 | |
| Not Equal | Is.NotEqual(3) | null, "bar" | 3 | |
| Null | Is.Null() | null | 5, new object() | |
| Not Null | Is.NotNull() | new object(), DateTime.Now | null | |
| Type Of | Is.TypeOf(typeof(Customer)) or Is.TypeOf<Customer>() | myCustomer, new Customer() | null, "str" | |
| Greater Than | Is.GreaterThan(10) | 15,53 | 2,10 | |
| Greater Than Or Equal | Is.GreaterThanOrEqual(10) | 10,15,43 | 9,3 | |
| Less Than | Is.LessThan(10) | 1,2,3,9 | 10,34 | |
| Less Than Or Equal | Is.LessThanOrEqual(10) | 10,9,2,0 | 34,53,99 | |
| Matching | Is.Matching(Predicate<T>) | |||
| Same | Is.Same(object) | |||
| NotSame | Is.NotSame(object) | |||
| Property | Equal To Value | Property.Value("Length",0) | new ArrayList() | "Hello", null |
| Null | Property.IsNull("InnerException") | new Exception("exception without inner exception") | new Exception("Exception with inner Exception", new Exception("Inner") | |
| Not Null | Property.IsNotNull("InnerException") | new Exception("Exception with inner Exception", new Exception("Inner") | new Exception("exception without inner exception") | |
| List | Is In List [the parameter is a collection that contains this value] | List.IsIn(4) | new int[]{1,2,3,4}, new int[]{4,5,6} | new object[]{"",3} |
| One Of [parameter equal to one of the objects in this list] | List.OneOf(new int[]{3,4,5}) | 3,4,5 | 9,1,"" | |
| Equal | List.Equal(new int[]{4,5,6}) | new int[]{4,5,6}, new object[]{4,5,6} | new int[]{4,5,6,7} | |
| Text | Starts With | Text.StartsWith("Hello") | "Hello, World", "Hello, Rhino Mocks" | "", "Bye, Bye" |
| Ends With | Text.EndsWith("World") | "World","Champion Of The World" | "world", "World Seria" | |
| Contains | Text.Contains("or") | "The Horror Movie...", "Either that or this" | "Movie Of The Year" | |
| Like [Perform regular expression validation] | Text.Like("rhino|Rhinoceros|rhinoceros") | "Rhino Mocks", "Red Rhinoceros" | "Hello world", "Foo bar", Another boring example string" |
Read more: Rhino Mocks documentation
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