This is one of those blog posts I write to remind my future self how I fixed a problem.

The Problem

I have a release that installs VSTest and runs some integration tests that target .NET 4.6 x64. All these tests worked fine in Visual Studio. However, I got the following errors for all tests when they were run in a release

2020-04-23T09:30:38.7544708Z vstest.console.exe "C:agent\_workr1aPaymentServicesdroptestartifactsPaymentService.IntegrationTests.dll"

2020-04-23T09:30:38.7545688Z /Settings:"C:agent\_work\_tempuxykzf03ik2.tmp.runsettings"

2020-04-23T09:30:38.7545808Z /Logger:"trx"

2020-04-23T09:30:38.7545937Z /TestAdapterPath:"C:agent\_workr1aPaymentServicesdroptestartifacts"

2020-04-23T09:30:39.2634578Z Starting test execution, please wait...

2020-04-23T09:30:39.4783658Z A total of 1 test files matched the specified pattern.

2020-04-23T09:30:40.8660112Z   X Can\_Get\_MIDs \[521ms\]

2020-04-23T09:30:40.8684249Z   Error Message:

2020-04-23T09:30:40.8684441Z    Test method PaymentServices.IntegrationTests.ControllerMIDTests.Can\_Get\_MIDs threw exception: 

2020-04-23T09:30:40.8684574Z System.BadImageFormatException: Could not load file or assembly 'PaymentServices, Version=, Culture=neutral, PublicKeyToken=null' or one of its dependencies. An attempt was made to load a program with an incorrect format.

2020-04-23T09:30:40.8684766Z   Stack Trace:

2020-04-23T09:30:40.8684881Z       at PaymentServices.IntegrationTests.ControllerMIDTests.Can\_Get\_MIDs()


2020-04-23T09:30:40.9038788Z Results File: C:agent\_work\_tempTestResultssvc-devops\_SVRHQAPP027\_2020-04-23\_10\_30\_40.trx

2020-04-23T09:30:40.9080344Z Total tests: 22

2020-04-23T09:30:40.9082348Z      Failed: 22

2020-04-23T09:30:40.9134858Z ##\[error\]Test Run Failed.


I needed to tell vstest.console.exe to run x64 as opposed to it’s default of x32. This can be done with a command line override –platform:x64