Fix bug in retrieving exponential correction parameters in auto detection mode of Reflectometry Reduction One Auto algorithm

[adriazalvarez]

Description of work

The issue is explained in #38204 : parameters for exponential correction were not being correctly retrieved when in autodetect mode, as the instrument parameters were being retrieved as string, but in the case of the exponential parameters, these are better retrieved as numbers. On the other hand, the polynomial parameters have the flexibility of being input as a double list or string with comma separated values for the parameters.

Additional changes:

• I have re-set the value of the correction parameters in the calling algorithm ReflectometryReductionOneAuto.
• I have added two tests to check that the correction parameters are being properly called in AutoDetect mode both for exponential corrections and polynomial corrections.

Summary of work

Fixes #38204

Further detail of work

To test:

• Follow testing instructions on ReflectometryReductionOneAuto fails to look up exponential algorithm parameters #38204 and make sure that the parameters are properly set by looking at the history.

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[rbauststfc]

I've tested the changes using both an INTER (polynomial correction) and SURF (exponential correction) example and both are working really well - the correct algorithm is selected and the parameters are looked up successfully from the parameter file.

Just a small thing I noticed (sorry, I couldn't seem to add a comment on the specific line because it's outside the changes in the PR) - the error message on line 610 refers to polynomial correction, but I think the error could technically have been thrown for either correction. It looks like this wasn't made more generic when the exponential correction was added in, so could we update this while we're here?

It's really great to have some tests added to cover this functionality. I've just included a comment to think about how we might make these robust against any future changes in instrument parameter file settings.

[adriazalvarez]

Thanks for the careful review and the useful tips.
I have changed the throw error message to refer to Algorithmic correction instead of just Polynomial correction.

[rbauststfc]

Thanks very much for investigating using a test parameter file in the unit tests, it's great to have that working and it should hopefully help to make the test more robust over the long-term. It looks like there's an import in the unit test file that's left over from before the recent changes that I think we could remove, but otherwise all the code changes are looking really good!

I think the CI failures are unrelated to your changes, there seem to be failures on a few PRs, so I'll flag to the Dev Ops team just in case.

[rbauststfc]

Thanks very much Adrian for your hard work getting the test parameter file to work in the unit tests. All the code changes are looking good, the fix is working well and all review comments have been addressed, so this looks good to go in. 👍