We’re using Xunit for testing. We’re running our tests via the built-in Visual Studio 2013 Test Runner, using the Xunit plugin.
The issue is that some of the tests need to refer to files on the filesystem. It seems that Xunit (or the VS Test Runner—not sure which), copies the assembles, but not any supporting files in the bin directory, to another directory before executing the tests, hence our test files are not found. [The MS Testing framework specifies attributes for listing files to be copied, but Xunit does not.]
How to either disable this copying behaviour, or else programmatically determine the original bin/ directory location to fetch the files?
It seems that most proposed solutions (including on the Xunit bug-tracker site) suggest storing the files as embedded resources instead of ‘copy always’ files. However, this is not always practical, for example: testing file manipulation code, and (in one case) code which wants a Sqlite database file.
Okay, typical, just as soon as I post the question, I find the answer myself…
The gist is that the copying (Shadow Copying) of assemblies seems to be done by the .NET framework, not by Visual Studio or by Xunit.
We had been using Assembly.Location to locate the assembly file, and hence the test files. However, this was wrong, since it gave us the location of the Shadow-Copied assembles instead of the originals.
Instead you should use Assembly.CodeBase to fetch the base assembly code location. However, this is a (File) URL, so it’s necessary to extract the path from the URL. The new (C#) code looks like this:
var codeBaseUrl = new Uri(Assembly.GetExecutingAssembly().CodeBase);
var codeBasePath = Uri.UnescapeDataString(codeBaseUrl.AbsolutePath);
var dirPath = Path.GetDirectoryName(codeBasePath);
return Path.Combine(dirPath, relativePath);
…where relativePath is the path relative to the Bin\ directory.