--- title: "Isolator feature focus: Recursive Fakes" url: "https://osherove.com/blog/2008/10/4/isolator-feature-focus-recursive-fakes.md" canonical: "https://osherove.com/blog/2008/10/4/isolator-feature-focus-recursive-fakes.html" published: "2008-10-04T15:17:05" updated: "2008-10-04T15:17:05" tags: [".NET", "Agile", "FeatureFocus", "Typemock", "Unit Testing"] author: "Roy Osherove" description: "Here’s another feature Typemock Isolator has that no one else currently has: the ability to return fake objects from properties recursively (without the use of an auto mocking container for such a feat). this saved a…" usage: "Licensed under CC BY 4.0 — reuse, quote and adapt with attribution (Roy Osherove, link to the original page)." license: "https://creativecommons.org/licenses/by/4.0/" --- # Isolator feature focus: Recursive Fakes By Roy Osherove October 4, 2008 In [.NET](https://osherove.com/blog/category/net), [Agile](https://osherove.com/blog/category/agile), [FeatureFocus](https://osherove.com/blog/category/featurefocus), [Typemock](https://osherove.com/blog/category/typemock), [Unit Testing](https://osherove.com/blog/category/unit-testing) **Historical article** · Originally published October 4, 2008; technical details may be outdated. Here’s another feature [Typemock Isolator](http://www.typemock.com/) has that no one else currently has: the ability to return fake objects from properties recursively (without the use of an auto mocking container for such a feat). this saved **a lot** of reperitive test code of creating stubs that return stubs that return some custom result. For example, an object person has a manager which is also a person (which of course also has a manager etc..) here’s how you can use this feature: \[Test,Isolated\] public void test() {     Person person = Isolate.Fake.Instance(Members.ReturnRecursiveFakes);     Assert.IsNotNull(person.Manager.Manager.Manager.Manager); } This test will pass (Manager is null by default. look at the class in question below: class Person    {        public string Name        {            get { return name; }        }        public Person Manager        {            get { return manager; }        }        private string name;        private Person manager;    } Here is how you can return stub results from properties of the stubbed objects: \[Test,Isolated\] public void test() {     Person person = Isolate.Fake.Instance(Members.ReturnRecursiveFakes);     Isolate.WhenCalled(() => person.Manager.Manager.Name)                .WillReturn("roy");     Assert.AreEqual("roy",person.Manager.Manager.Name); } Notice that: - By saying “ReturnRecursiveFakes” we are actually saying “I don’t care who uses this object and how from now on. It will return a fake when needed from all properties and the properties of the stubs as well. - We can still set stub results on the fakes on any level If we wanted to only fake the Manager name and leave everything else intact we could just use a live object in the test like this: \[Test,Isolated\] public void test() {     **Person person = new Person();**     Isolate.WhenCalled(() => person.Manager.Manager.Name)                .WillReturn("roy");     Assert.AreEqual("roy",person.Manager.Manager.Name); } ## Lessons on this topic - [Recursive Fakes](https://courses.osherove.com/courses/tdd-in-net-in-hebrew/recursive-fakes/) · TDD in .NET in Hebrew - [Testing Legacy Code with Typemock Isolator Deep Dive](https://courses.osherove.com/courses/the-art-of-unit-testing-and-tdd-master-class-in-net/testing-legacy-code-with-typemock-isolator-deep-dive/) · The Art of Unit Testing & TDD Master Class in .NET - [Isolation Frameworks](https://courses.osherove.com/courses/the-art-of-unit-testing-and-tdd-master-class-in-net/isolation-frameworks/) · The Art of Unit Testing & TDD Master Class in .NET - [Test Review Practices](https://courses.osherove.com/courses/the-art-of-unit-testing-and-tdd-master-class-in-net/test-review-practices/) · The Art of Unit Testing & TDD Master Class in .NET ## More in .NET [All posts in .NET](https://osherove.com/blog/category/net) - Oct 6, 2008 ### [Graphic Designer Wanted (and found)](https://osherove.com/blog/2008/10/6/graphic-designer-wanted-and-found.html) - Oct 6, 2008 ### [Deadlock Challenge](https://osherove.com/blog/2008/10/6/deadlock-challenge.html) - Oct 4, 2008 ### [BDD: Behavior vs. Spec Frameworks](https://osherove.com/blog/2008/10/4/bdd-behavior-vs-spec-frameworks.html) - Oct 3, 2008 ### [Agile Testing tools List](https://osherove.com/blog/2008/10/3/agile-testing-tools-list.html) --- ## About the author **Roy Osherove**: Senior Solutions Architect at AWS working on AI for production and AI-driven development; author of The Art of Unit Testing and Elastic Leadership, with about 20 years of consulting and training on unit testing, TDD, team leadership and continuous delivery. ### Sites - [RobotPaper](https://robotpaper.ai/): This blog: AI patterns and anti-patterns, AI and coding agents, and engineering leadership. - [osherove.com](https://osherove.com): Roy's personal site. Author of The Art of Unit Testing and Elastic Leadership; consulting and training on unit testing, TDD, team leadership and continuous delivery, plus about 20 years of blog posts. - [The Art of Unit Testing](https://www.artofunittesting.com): The Art of Unit Testing, 3rd Edition (Manning): readable, maintainable, trustworthy unit tests, plus TDD workshops in C#, JavaScript, Java and Kotlin. - [5whys.com](https://www.5whys.com): Roy's writing on software team leadership: self-organizing teams, surviving chaos, learning mode and the Elastic Leadership model. - [Pipeline Driven](https://pipelinedriven.org): Continuous delivery and DevOps practices: build patterns, pipeline-friendly testing, DevOps metrics and enterprise DevOps. - [Elastic Leadership](https://www.elasticleadership.com): Elastic Leadership, Roy's framework for software team leaders (survival, learning and self-organizing modes). ### Social - X: https://x.com/royosherove - LinkedIn: https://www.linkedin.com/in/osherove/ ### Contact - Contact form: https://forms.gle/jQSx5KoXvrVA1JCK7 ### License Licensed under CC BY 4.0 — reuse, quote and adapt with attribution (Roy Osherove, link to the original page). License: https://creativecommons.org/licenses/by/4.0/