AsmSpy on Artifacts Verification

November 8, 2022

We often perform artifacts verification via test suites, so for .NET projects NUnit/ might be quite helpful. However, there is a kind of issues that cannot be easily caught by test suites, and I found AsmSpy a perfect tool in this field. In this post, I will give an example.

Out-Of-Control Dependent Assembly Versions

I have shipped multiple versions of PHP Manager for IIS in the past few years, but it was recently that one issue reported back on Microsoft.Web.Administration reference,

Could not load file or assembly 'Microsoft.Web.Administration, Version=, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system
 cannot find the file specified.

I think you might have seen similar exceptions in the past, and not surprised at all. I blogged about the cause and solution a long while ago, so fixing the bug was just a few minutes.

The Long Term Defense

However, this time I started to think about whether I could find a permanent way to prevent it from happening again, such as a verification step in CI manifest. Of course, I can write a tool based on Mono Cecil which won’t take much long, but doesn’t a tool exist already?

I did search for a while and found many tools in this field relying on project files (*.csproj). While they can be useful in some scenarios, clearly they cannot be used for this specific task that relies on assembly scan.

AsmSpy was not at the top of search results, but turned out to be good enough for my case. Install it via Chocolatey, and then I can easily generate a report of all referenced assemblies in an output folder. A simple search in that report in AsmSpy console output can identify any unexpected assembly versions. Thus, I added this step in verify.ps1.

If your projects face similar challenges and want to identify compilation issues early, check out AsmSpy and it’s a nice addition to your toolbox.

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