Fix Moq test the right way

[evildour]

This fixes an incorrect "workaround" in #1372 for something I thought was a Moq regression, but it was just my misunderstanding how Moq works. Lesson learned: don't modify captured variables in argument match conditions for Moq setups.

[codecov]

Codecov Report

Merging #1397 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1397   +/-   ##
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  Coverage   61.27%   61.27%           
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  Files         299      299           
  Lines        8020     8020           
=======================================
  Hits         4914     4914           
  Misses       3106     3106

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[ILMTitan]

Right, because Mock.Setup does not take a Function<...>, it takes an Expression<Function<...>>

[evildour]

That was not what I got wrong. I mistakenly assumed the setup with match predicates on the arguments was validating the arguments, instead of testing them to see if the setup applies. If you're interested, here is where I realized my mistake and then had it explained to me.