Running Typemock Isolator based tests in TFS vNext build

Updated 22 Mar 2016 This task is available in the VSTS Marketplace

Typemock Isolator provides a way to ‘mock the un-mockable’, such as sealed private classes in .NET, so can be a invaluable tool in unit testing. To allow this mocking Isolator interception has to be started before any unit tests are run and stopped when completed. For a developer this is done automatically within the Visual Studio IDE, but on build systems you have to run something to do this as part of your build process. Typemock provide documentation and tools for common build systems such as MSBuild, Jenkins, Team City and TFS XAML builds. However, they don’t provide tools or documentation on getting it working with TFS vNext build, so I had to write my own vNext build Task to do the job, wrapping Tmockrunner.exe provided by Typemock which handles the starting and stopping of mocking whilst calling any EXE of your choice.

tmockrunner <name of the test tool to run> <and parameters for the test tool>

Microsoft provide a vNext build task to run the vstest.console.exe. This task generates all the command line parameters needed depending on the arguments provided for the build task. The source for this can be found on any build VM (in the [build agent folder]\tasks folder after a build has run) or on Microsoft’s vso agent github repo. I decided to use this as my starting point, swapping the logic to generate the tmockrunner.exe command line as opposed to the one for vstest.console.exe. You can find my task on my github. It has been developed in the same manner as the Microsoft provided tasks, this means the process to build and use the task is

  1. Clone the repo
  2. In the root of the repo use gulp to build the task
  3. Use tfx to upload the task to your TFS or VSO instance

See and for a good walkthroughs of building tasks, the process is the same for mine and Microsoft’s tasks.

IMPORTANT NOTE: This task is only for on premises TFS vNext build instances connected to either an on premises TFS or VSO. Typemock at the time of writing this post does not support VSO’s host build agents. This is because the registration of Typemock requires admin rights on the build agent which you only get if you ‘own’ the build agent VM

Once the task is installed on your TFS/VSO server you can use it in vNext builds. You will note that it takes all the same parameters as the standard VSTest task (it will usually be used as a replacement when there are Typemock Isolator based tests in a solution). The only addition to the parameters are the three parameters for Typemock licensing and deployment location.


Using the task allows tests that require Typemock Isolator to pass. So test that if run with the standard VSTest task give


With the new task gives