Refine test suite scripts

[DimmestP]

From Edwards comments on pull request #92

1. Explain the test data

I am finding it hard to understand the data in the tests, even though I am meant to know this code very well.
Could we describe in a comment what each plate plan and data means? For example:

This is a sample dataset with x samples and y reps, that we use for…

Bonus points for having some lines to visualise the data??? Maybe???

5. Is there still scope to simplify?

Now we have good code coverage, is it possible to write even simpler unit tests for core capabilities of the function? E.G. with smallest-possible dataframes?

Or without a +RT column so that we don’t need a filter(Type == “+RT”) in a test.