Support both merge backends in the testsuite, via environment variable

This patch series builds on top of en/dir-rename-tests. It can be applied independent of my "new merge-ort" API series I submitted a couple days ago[1], but this series uses the same environment variable as patch 4 of that series.

As promised, here is a series that makes the testsuite changes needed to simultaneously support both merge backends, keyed off a GIT_TEST_MERGE_ALGORITHM environment variable setting.

NOTE: The tests do not yet pass with GIT_TEST_MERGE_ALGORITHM=ort, because I haven't submitted the implementation of the merge-ort functions -- yet. I figured they are useful as a high level overview of the differences in behavior between the two backends, and thus am providing these before the implementation.

Changes since v1:

* Minor tweak to test_expect_merge_algorithm() suggested by Junio
* Updated a test for portability
* I had meant to leave the final patch, patch 9, out of the submission. But, since I submitted it, update it to match my local version of that test with one additional thing checked in the result.

[1]
https://lore.kernel.org/git/[email protected]/

Elijah Newren (9):
t/: new helper for tests that pass with ort but fail with recursive merge tests: expect improved directory/file conflict handling in ort
t6416: correct expectation for rename/rename(1to2) + directory/file t6404, t6423: expect improved rename/delete handling in ort backend
t6423: expect improved conflict markers labels in the ort backend merge tests: expect slight differences in output for recursive vs. ort t6423, t6436: note improved ort handling with dirty files
t6423: note improved ort handling with untracked files
t6423: add more details about direct resolution of directories

 t/lib-merge.sh                         |  13 +
 t/t6400-merge-df.sh                    |  14 +-
 t/t6402-merge-rename.sh                | 122 ++++-
 t/t6404-recursive-merge.sh             |  14 +-
 t/t6416-recursive-corner-cases.sh      | 200 ++++---
 t/t6422-merge-rename-corner-cases.sh   |  37 +-
 t/t6423-merge-rename-directories.sh    | 706 +++++++++++++++----------
 t/t6426-merge-skip-unneeded-updates.sh |   3 +-
 t/t6430-merge-recursive.sh             |   3 +-
 t/t6436-merge-overwrite.sh             |  18 +-
 t/t6437-submodule-merge.sh             |  25 +-
 t/t7602-merge-octopus-many.sh          |   6 +
 t/t7610-mergetool.sh                   |  32 +-
 13 files changed, 807 insertions(+), 386 deletions(-)
 create mode 100644 t/lib-merge.sh

base-commit: c64432aacda9054459ce550eca95929897c301bd
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-769%2Fnewren%2Ftests-support-both-merge-backends-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-769/newren/tests-support-both-merge-backends-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/769

Range-diff vs v1:

1: a8d4825a32 ! 1: f5d3295262 t/: new helper for tests that pass with ort but fail with recursive

     @@ t/lib-merge.sh (new)
      +# Helper functions used by merge tests.
      +
      +test_expect_merge_algorithm () {
     -+	status_for_recursive=$1
     -+	shift
     -+	status_for_ort=$1
     -+	shift
     ++	status_for_recursive=$1 status_for_ort=$2
     ++	shift 2
      +
      +	if test "$GIT_TEST_MERGE_ALGORITHM" = ort
      +	then
  2:  9394d526f1 =  2:  f27f12e8e5 merge tests: expect improved directory/file conflict handling in ort
  3:  1eae84b787 =  3:  38919982c4 t6416: correct expectation for rename/rename(1to2) + directory/file
  4:  554feb2aa7 =  4:  6e47fa19f8 t6404, t6423: expect improved rename/delete handling in ort backend
  5:  5bead7fa0d =  5:  e8a7d6ac81 t6423: expect improved conflict markers labels in the ort backend
  6:  2aa44c1f13 !  6:  4f32450b08 merge tests: expect slight differences in output for recursive vs. ort
     @@ t/t7602-merge-octopus-many.sh: Merge made by the 'recursive' strategy.
       test_expect_success 'merge reduces irrelevant remote heads' '
      +	if test "$GIT_TEST_MERGE_ALGORITHM" = ort
      +	then
     -+		sed -i'' s/recursive/ort/ expected
     ++		mv expected expected.tmp &&
     ++		sed s/recursive/ort/ expected.tmp >expected &&
     ++		rm expected.tmp
      +	fi &&
       	GIT_MERGE_VERBOSITY=0 git merge c4 c5 >actual &&
       	test_i18ncmp expected actual
  7:  9d46cc1ef3 =  7:  c5350fd0ae t6423, t6436: note improved ort handling with dirty files
  8:  436577106e =  8:  6fd224247d t6423: note improved ort handling with untracked files
  9:  2659d1cb98 !  9:  6e308768ff t6423: add more details about direct resolution of directories
     @@ t/t6423-merge-rename-directories.sh: test_expect_merge_algorithm failure success
      +		test_cmp expect actual &&
      +
      +		grep region_enter.*collect_merge_info trace.output >collect &&
     -+		test_line_count = 4 collect
     ++		test_line_count = 4 collect &&
     ++		grep region_enter.*process_entries$ trace.output >process &&
     ++		test_line_count = 2 process
       	)
       '

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