Unit Test Adapter threw exception: Unable to load one or more of the requested types

I am attempting to run SpecFlow tests from the Visual Studio 2010 Command Prompt, and I am getting a rather obtuse error message:

Unit Test Adapter threw exception: Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information..

Some info about my VS2010 Project setup:

Windows 7 Enterprise, 64 bit (Version 6.1.7601 Service Pack 1 Build 7601)
Visual Studio 2010 Premium (v10.0.40219.1 SP1Rel)
Using Coded UI Tests
Using SpecFlow 1.9.0, which delegates to the CodedUI test API
MSTest
.NET v4.0.30319
Whole solution is compiling to 32 bit code (I have coworkers using XP still)

I have a post-build event that copies a few DLL files from my NuGet packages directory to the target dir:

copy $(SolutionDir)packages\SpecBind.1.2.1.71\lib\net45\SpecBind.dll $(TargetDir)
copy $(SolutionDir)packages\SpecBind.CodedUI.1.2.1.71\lib\net45\SpecBind.CodedUI.dll $(TargetDir)

Without this, mstest somehow couldn't load a number of SpecFlow assemblies.

Relevant Parts of Test Project's App.config

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
    <section name="specFlow" type="TechTalk.SpecFlow.Configuration.ConfigurationSectionHandler, TechTalk.SpecFlow" />
    <section name="specBind" type="SpecBind.Configuration.ConfigurationSectionHandler, SpecBind" />
  </configSections>

  <connectionStrings>
    ...
  </connectionStrings>

  <specFlow>
    <!-- For additional details on SpecFlow configuration options see http://go.specflow.org/doc-config -->
    <unitTestProvider name="MsTest" generatorProvider="Specflow.CodedUI.MsTestCodedUiGeneratorProvider, Specflow.CodedUI" runtimeProvider="TechTalk.SpecFlow.UnitTestProvider.MsTest2010RuntimeProvider, TechTalk.SpecFlow" />
    <stepAssemblies>
      <!-- This attribute is required in order to use StepArgument Transformation as described here; 
           https://github.com/marcusoftnet/SpecFlow.Assist.Dynamic/wiki/Step-argument-transformations  -->
      <stepAssembly assembly="SpecFlow.Assist.Dynamic" />
      <stepAssembly assembly="SpecBind" />
    </stepAssemblies>
  </specFlow>
  <specBind>
    <browserFactory provider="SpecBind.CodedUI.CodedUIBrowserFactory, SpecBind.CodedUI" browserType="IE" />
    <!-- For additional details on SpecBind configuration options see the project site. -->
  </specBind>
</configuration>

The command I was using to start the tests:

C:\path\to\bin\Debug> mstest /testcontainer:MyTests.dll /test:SpecFlowFeatureName

Loading MyTests.dll
Starting Execution...

Results         Top Level Tests
--------        ------------------
Failed          ...
Failed          ...
Failed          ...

...

I've been searching high and low for a solution, and all I keep finding is references to VS2008 and disabling Code Coverage. I have VS2010 and Code Coverage is not enabled in my local test settings.

Windows Event Log Viewer

After rooting around in my Windows Event Log viewer, I finally came across more info (I've heard people complain they can't find a stack trace with this error -- look in your Event Viewer)

The description for Event ID 0 from source VSTTExecution cannot be found. Either the component that raises this event is not installed on your local computer or the installation is corrupted. You can install or repair the component on the local computer.

If the event originated on another computer, the display information had to be saved with the event.

The following information was included with the event: 

(QTAgent32.exe, PID 6920, Thread 213) Unit Test Adapter threw exception: System.Reflection.ReflectionTypeLoadException: Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.
   at System.Reflection.RuntimeModule.GetTypes(RuntimeModule module)
   at System.Reflection.RuntimeModule.GetTypes()
   at System.Reflection.Assembly.GetTypes()
   at Microsoft.VisualStudio.TestTools.TestTypes.Unit.UnitTestExecuter.GetAssemblyInfo(Assembly assembly)
   at Microsoft.VisualStudio.TestTools.TestTypes.Unit.UnitTestExecuter.GetTypeInfo(Type type, Boolean checkAlreadyExaminedType)
   at Microsoft.VisualStudio.TestTools.TestTypes.Unit.UnitTestExecuter.ResolveMethods()
   at Microsoft.VisualStudio.TestTools.TestTypes.Unit.UnitTestExecuter.Initialize(UnitTestResult result, UnitTestRunner runner, ConsoleOutputRedirector redirector)
   at Microsoft.VisualStudio.TestTools.TestTypes.Unit.UnitTestRunner.Run(UnitTestElement test, ITestContext testContext, Boolean isLoadTest, Boolean useMultipleCpus)

the message resource is present but the message is not found in the string/message table

I don't know how to resolve this error. SpecFlow tests run fine from inside Visual Studio when I right-click in a .feature file loaded in the editor and choose "Run SpecFlow Scenarios..." but I can't run them from the command line.

Any ideas, or additional information I could post?

As a side note, this stemmed from my earlier question: How do you run SpecFlow scenarios from the command line using MSTest?

Update #1

I did a little more poking around, and found this blog post: MSTest and 64bit. I checked my local test settings, and it is forcing the tests to run in 32 bit.

Now using this command:

mstest /testcontainer:MyTests.dll /testsettings:"..\..\..\Local.testsettings"

Error message:

Test method Blah.Dee.Blah threw exception: 
System.IO.FileNotFoundException: Could not load file or assembly 'Microsoft.VisualStudio.TestTools.UITest.Extension, Version=11.0.0.0, Culture=neutral, PublicKeyToken=...' or one of its dependencies. The system cannot find the file specified.WRN: Assembly binding logging is turned OFF.
To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1.
Note: There is some performance penalty associated with assembly bind failure logging.
To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog].

TestCleanup method Blah.Dee.Blah.ScenarioTearDown threw exception. BoDi.ObjectContainerException: BoDi.ObjectContainerException: Interface cannot be resolved: SpecBind.BrowserSupport.IBrowser.

Update #2

I removed the reference to Microsoft.VisualStudio.TestTools.UITest.Extension and added it back. Cleaned. Rebuilt. Ran the same command again. Still getting the same error.

For some reason it's trying to load the Microsoft.VisualStudio.TestTools.UITest.Extension assembly as Version 11, and I have Version 10 installed on my machine. I'm trying to track down where this version is being specified so I can change it.

Chris

Just in case anyone else comes across this, for me it was because code coverage was enabled. Disabling it resolved the issue:

http://blogs.msdn.com/b/danielvl/archive/2010/02/16/enable-code-coverage-in-visual-studio.aspx

Open the .testsettings file
Under "Test Settings", click "Data and Diagnostics"
Uncheck "Code Coverage"
Hit "Apply"

Greg Burghardt

With the help of @jessehouwing's comment above, I've got this fixed. I was running into two problems.

The error I originally referenced was actually caused by mstest attempting to run the tests in a 64bit process (QTAgent.exe). I needed it to run as a 32 bit process because the project was compiled as 32 bit code on my 64 bit Windows 7 machine.

In Visual Studio 2010:

Click the "Test" menu -> "Edit Test Settings" -> "Local (local.testsettings)"
Click "Hosts" in the left hand panel
Make sure "Force tests to run in 32 bit process" is chosen in the "Run tests in 32 bit or 64 bit process" drop down. For me this was the default
In the Visual Studio Command Prompt, run the tests by referencing the local.testsettings file generated by Visual Studio:
```
mstest /testcontainer:foo.dll /testsettings:"path/to/solution/local.testsettings" /test:SpecFlowFeatureName
```

The second problem I had was my own fault. Earlier I was playing around with Coded UI tests and SpecFlow and had installed SpecBind, which threw a bunch of settings in App.config for my test project. This NuGet package is only for .NET 4.5, and we use .NET 4.0. I removed that NuGet package and settings from App.config, cleaned and rebuilt. This fixed this issue completely.

So in short, I:

Forced mstest to run in a 32 bit process, and referenced this local.testsettings file from the command line
Removed all references to SpecBind because I got a little NuGet-happy earlier and installed a package incompatible with my .NET runtime.

As you can see by looking at the assembly references required by these packages (I use Reflector for this, but IlSpy or JetBrains' DotPeek will work as well), you'll see that they depend on the v11 version, which is the version that ships with Visual Studio 2012. These can't be used in Visual Studio 2010.

Removing SpecBind will probably help, or finding a version that depends on an older version of CodedUI (you're probably looking for a much older version of SpecBind in this case).

As for your 32-bit issue, you should probably set your project's CPU configuration to AnyCPU, there is normally no need to fix it to x86, unless you're dependent on native methods or if you're referencing other assemblies that are specifically set to use x86 as their target architecture.

Nabil Shaik

This is so troubling.....

I had Test Agent for Visual Studio 2015 installed on my test machine, since we were planning to use it - while on my local machine I had 2013. The tests ran so perfectly with MsBuild on local, that I couldn't understand what could have happened given that I always assumed Microsoft always maintained backward compatability.

MsBuild on test server failed to give any information as to what assemblies were missing (I added Newtonsoft.Json just because it complained initially, but after that I never saw the names of anything else missing). The error message was truncated, stacktrace and debugtrace options never worked...

Once I installed Test Agent for Visual Studio 2013 on the test machine, it ran like a charm.

来源：https://stackoverflow.com/questions/20909195/unit-test-adapter-threw-exception-unable-to-load-one-or-more-of-the-requested-t

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