SubmoduleTests: Setup repos once for all tests

[gerhardol]

Fixes #8279

Proposed changes

Setup the Git repos used in the tests only once, to speed up tests.
For me, test time goes down from 1,6 mon to 11s, about twice the time for one test. (Longer time for other users.)

• Setup attributes for Parallelizable to disallow the individual tests in parallel

More comments in the code

I consider this to be a major hack.

Test methodology

Tests only

Test environment(s)

• Git Extensions 33.33.33
• Build da7659f
• Git 2.27.0.windows.1
• Microsoft Windows NT 10.0.18362.0
• .NET Framework 4.8.4180.0
• DPI 96dpi (no scaling)

---

✒️ I contribute this code under The Developer Certificate of Origin.

[codecov]

Codecov Report

Merging #8334 into master will decrease coverage by 0.06%.
The diff coverage is 48.71%.

@@            Coverage Diff             @@
##           master    #8334      +/-   ##
==========================================
- Coverage   52.77%   52.70%   -0.07%     
==========================================
  Files         866      866              
  Lines       62691    62615      -76     
  Branches    11300    11289      -11     
==========================================
- Hits        33083    33000      -83     
- Misses      26965    26972       +7     
  Partials     2643     2643              

Flag	Coverage Δ
#production	40.74% <ø> (-0.03%)	⬇️
#tests	94.22% <48.71%> (+<0.01%)	⬆️

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

[mstv]

[OneTimeSetUp] cannot be used, as the setup must run after BeforeTest in CommonTestUtils\ConfigureJoinableTaskFactoryAttribute.cs

We should keep this in mind for all tests. CC: @sharwell

[mstv]

Quick formal comparison with previous.

[RussKie]

Tests shouldn't concern themselves with resetting the state after execution. I was thinking of a change along the lines of ReferenceRepoistory:

            if (_repo1 is null)
            {
                _repo1 = new GitModuleTestHelper("repo1");
            }
            else
            {
                _repo1.Reset();
            }

Do you think we can re-write these tests to utilise ReferenceRepository instead?

[gerhardol]

The repos would need not just to reset, but also undo commits. That would require that the initial commit have to be remembered, which will make a more complex setup. Also, a reset will increase the test time slightly.
The test cases cleaning up is much easier.

[gerhardol]

A clean is needed too, in addition to reset and checkout.

[RussKie]

Much better now:

[RussKie]

However on my work machine tests fail to stage and I need 649552a.

[gerhardol]

Much better now:

The tests requiring a second basically runs UpdateSubmoduleStructureAndWaitForResultAsync() for top module (a series of commands parsing .gitmodules creating GitModules recursively) then a couple of git-status from top module and one or two other commands.

Stepping in one test case, one time: Submodule_status_changes_for_top_module_with_first_nested_module_commit_second_nested_module_change
1.1s without setup in debug, 550 ms normally
Repo setup: 6.6 s
UpdateSubmoduleStructureAndWaitForResultAsync: 30 ms
// No changes in repo
First status 114ms
UpdateSubmoduleStatusAndWaitForResultAsync 8 ms
// Make a change in repo3
Commit 8ms
Status 175 ms
UpdateSubmoduleStatusAndWaitForResultAsync 75 ms
// Revert the change for repo3
Status 331ms
UpdateSubmoduleStatusAndWaitForResultAsync 78 ms
// Revert the change
checkout 64 ms
CheckRevertedStatus 76 ms (git-status)

Git status is cached, the time cannot be taken out of context

However, the check that a repo is clean before and after adds 200 ms for this test. Slightly less for some, more for others.
Those could be excluded by default. Just excluding CheckRevertedStatus reduces execution time from 12,3 s to 10,9 s for me.
Harder to find why a test fails though.

Unless there are requests to optimize, I plan to merge in a day or so.

[RussKie]

Thank you. This is an improvement, let's merge it.