Get mirror immediate position

[dc2917]

Description

This PR enables getting the immediate position of stepper motors while they are moving.
Previously, querying the position during motion would return None. Now, for the ST10, an estimated position is returned.

I've had a go at making the dummy stepper motor return a position based on its QTimer interval and remaining time, but it's not fully complete, so we can either address that separately or I can finish it up here.

Fixes #691

Type of change

• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Documentation (non-breaking change that adds or improves the documentation)
• Optimisation (non-breaking, back-end change that speeds up the code)

Key checklist

• Pre-commit hooks run successfully (pre-commit run -a)
• All tests pass (pytest)
• The documentation builds without warnings (mkdocs build -s)
• Check the GUI still works (if relevant)
• Check the code works with actual hardware (if relevant)
• Check the pyinstaller-built executable works (if relevant)

Further checks

• Code is commented, particularly in hard-to-understand areas
• Tests have been added or an issue has been opened to tackle that in the future. (Indicate issue here: # (issue))

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.90%. Comparing base (bd2ba61) to head (9ec257a).
Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #743      +/-   ##
==========================================
+ Coverage   86.87%   86.90%   +0.03%     
==========================================
  Files          69       69              
  Lines        3557     3551       -6     
==========================================
- Hits         3090     3086       -4     
+ Misses        467      465       -2     

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[alexdewar]

I've made one suggestion about the test, but it otherwise looks good. Thanks for doing this!

I think it's fine to leave DummyStepperMotor as it is for now -- let's not make things hard for ourselves.

I've just realised that we also need to update data_file_writer.py, because we record whether or not the motor is moving as a column in the CSV file and it currently does this by checking whether the returned angle is None. Would you mind fixing this up too?

[dc2917]

I've just realised that we also need to update data_file_writer.py, because we record whether or not the motor is moving as a column in the CSV file and it currently does this by checking whether the returned angle is None. Would you mind fixing this up too?

I've removed that column from the CSV file entirely. I presume that's what we want, since the only way we check for whether the mirror is moving is if it returns None, which will never happen.

[alexdewar]

The stepper motor classes do have an is_moving property that you can use instead. Unfortunately we do need this column -- sorry I wasn't clear 😞

[alexdewar]

LGTM! Thanks for fixing up that extra file 😄