RevFile: Diff any two files

[gerhardol]

Based on #8193, for RevisionFileHistory

Proposed changes

Add Remember file for diff for RevisionFileHistory similar to RevDiff in #8193 The context is shared between the tabs

Screenshots

Before

After

Test methodology

Tests added for RevisionDiff

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

[codecov]

Codecov Report

Merging #8275 into master will decrease coverage by 0.02%.
The diff coverage is 25.64%.

@@            Coverage Diff             @@
##           master    #8275      +/-   ##
==========================================
- Coverage   52.80%   52.78%   -0.03%     
==========================================
  Files         857      857              
  Lines       62305    62339      +34     
  Branches    11190    11202      +12     
==========================================
+ Hits        32900    32904       +4     
- Misses      26799    26827      +28     
- Partials     2606     2608       +2     

Flag	Coverage Δ
#production	40.76% <25.64%> (-0.02%)	⬇️
#tests	94.44% <ø> (-0.02%)	⬇️

[RussKie]

I'm getting concerned with the size of our context menus.

[gerhardol]

I'm getting concerned with the size of our context menus.

RevFileTree is not that long, should not be a concern.

[mstv]

Another edge case only if the Working directory is selected:

I tried to get a diff with meaningful file names where, in addition, the current files can be edited.

[gerhardol]

Another edge case only if the Working directory is selected:

Intentional. If you select a commit, then work tree, Git can compare.
If you select worktree, then commit then no. Disabling the entry for all two selections where diff is not possible.
(Actually, worktree->worktree is possible but a separate case so just ignored.)

[RussKie]

LGTM

[gerhardol]

Handling posix paths. When @mstv has approved I will squash (probably keep difftool in folder separate) and rebase, then merge

[mstv]

Thank you

[gerhardol]

@msftbot merge in 24 hours

[ghost]

Hello @gerhardol!

Because you've given me some instructions on how to help merge this pull request, I'll be modifying my merge approach. Here's how I understand your requirements for merging this pull request:

• I won't merge this pull request until after the UTC date Thu, 02 Jul 2020 22:17:02 GMT, which is in 1 day

If this doesn't seem right to you, you can tell me to cancel these instructions and use the auto-merge policy that has been configured for this repository. Try telling me "forget everything I just told you".