output_collection file comparison is seemingly ignored

I have a tool with a test like:

```

...





```

irrespective of the content of the the bam files the test is successful. Same if compare="diff".

The `` are not completely ignored: if I give a wrong file name the test fails.

Locate the handling for Galaxy tool-test output_collection elements and reproduce the XML example with differing BAM contents. Check why compare="sim_size" and compare="diff" do not affect the result while an incorrect file name does; done means content comparisons fail when expected and pass for matching outputs.

Written by the indexing model from the issue text.