Disabled Progress should not start attached Live

[JoshKarpel]

Type of changes

• Bug fix
• New feature
• Documentation / docstrings
• Tests
• Other

Checklist

• I've run the latest black with default args on new code.
• I've updated CHANGELOG.md and CONTRIBUTORS.md where appropriate.
• I've added tests for new code.
• I accept that @willmcgugan may be pedantic in the code review.

Description

If you make a Progress that is disabled, it will still display an initial version of itself because it is the renderable of its attached Live, and the Live is started unconditionally in Progress.start. Example:

from rich.progress import Progress

with Progress(disable=True) as progress:
    task = progress.add_task("foobar", total=100)
    progress.update(task, advance=1)

print("done")

Running this produces this output:

With this patch, it produces this:

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I added some tests for this, but they're poking around the internals to do it - let me know if this isn't your preferred style.

[codecov]

Codecov Report

Merging #1125 (34c5620) into master (e08a838) will increase coverage by 0.06%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1125      +/-   ##
==========================================
+ Coverage   99.77%   99.84%   +0.06%     
==========================================
  Files          69       69              
  Lines        6322     6323       +1     
==========================================
+ Hits         6308     6313       +5     
+ Misses         14       10       -4     

Flag	Coverage Δ
unittests	99.84% <100.00%> (+0.06%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
rich/progress.py	98.04% <100.00%> (+0.98%)	⬆️

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[willmcgugan]

Thanks for this. Would you mind also testing the output? i.e. confirm that when disable=True nothing gets written. Just to catch any regression.

[willmcgugan]

Thanks.