Anthony Egerton

Anthony created NSubstitute and supplied the syntax ideas at the heart of its readable approach to .NET testing. Developers use the library to control dependencies and check how software interacts with them. Sharing the project as open source, alongside its announcement at Sydney ALT.NET, made this practical approach available to the wider testing and engineering community.

Anthony Egerton is an iOS developer in Sydney and the creator of NSubstitute, an open-source mocking library for .NET. The library allows developers to replace dependencies with controllable substitutes, prioritising clean, readable test code with straightforward syntax for setting return values and asserting calls.

The project originated during a pair-programming discussion about improving the readability of mocking code. Anthony proposed the initial syntax ideas, progressing from a spare-time project into an established tool used across work projects. In 2010, an announcement at Sydney ALT.NET introduced NSubstitute to the wider developer community.

NSubstitute enables developers to verify expected calls, confirm unwanted interactions do not occur and simulate events, supported by clear error messages detailing differences between expected and actual behaviour. These capabilities allow engineering teams to specify behaviour clearly and diagnose test failures quickly.