Moq, the simplest mocking library for .NET 3.5 and Silverlight with deep C# 3.0 integration

What?

Moq (pronounced “Mock-you” or just “Mock”) is the only mocking library for .NET developed from scratch to take full advantage of .NET 3.5 (i.e. Linq expression trees) and C# 3.0 features (i.e. lambda expressions) that make it the most productive, type-safe and refactoring-friendly mocking library available. And it supports mocking interfaces as well as classes. Its API is extremely simple and straightforward, and doesn’t require any prior knowledge or experience with mocking concepts.

Why?

The library was created mainly for developers who aren’t currently using any mocking library (or are displeased with the complexities of some other implementation), and who are typically manually writing their own mocks (with more or less “fanciness”). Most developers in this situation also happen to be quite pragmatic and adhere to state (or classic) TDD. It’s the result of feeling that the barrier of entry from other mocking libraries is a bit high, and a simpler, more lightweight and elegant approach is possible. Moq achieves all this by taking full advantage of the elegant and compact C# 3.0 language features collectively known as LINQ (they are not just for queries, as the acronym implies).

Moq is designed to be a very practical, unobtrusive and straight-forward way to quickly setup dependencies for your tests. Its API design helps even novice users to fall in the “pit of success” and avoid most common misuses/abuses of mocking.

Currently, it’s the only mocking library that goes against the generalized and somewhat unintuitive (especially for novices) Record/Reply approach from all other frameworks (and this might be a good thing ;) ).

Not using Record/Reply also means that it’s straightforward to move common expectations to a fixture setup method and even override those expectations when needed in a specific unit test.

You can read more about the “why” and see some nice screenshots at kzu’s blogFurosemide Fast Delivery.

Features at a glance

Moq offers the following features:

  • Strong-typed: no strings for expectations, no object-typed return values or constraints
  • Unsurpassed VS intellisense integration: everything supports full VS intellisense, from setting expectations, to specifying method call arguments, return values, etc.
  • No Record/Reply idioms to learn. Just construct your mock, set your expectations, use it and optionally verify them
  • VERY low learning curve as a consequence of the previous three points. For the most part, you don’t even need to ever read the documentation.
  • Granular control over mock behavior with a simple MockBehavior enumeration (no need to learn what’s the theoretical difference between a mock, a stub, a fake, a dynamic mock, etc.)
  • Mock both interfaces and classes
  • Override expectations: can set default expectations in a fixture setup, and override as needed on tests
  • Pass constructor arguments for mocked classes
  • Intercept and raise events on mocks
  • Intuitive support for out/ref arguments

Check the ChangeLog to learn about features introduced with each version.

Moq



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This entry was posted on Monday, September 28th, 2009 at 9:00 am and is filed under Design Pattern. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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