Define GIT_TEST_COMMIT_GRAPH for commit-graph test coverage

The commit-graph (and multi-pack-index) features are optional data structures that can make Git operations faster. Since they are optional, we do not enable them in most Git tests. The commit-graph is tested in t5318-commit-graph.sh (and t6600-test-reach.sh in ds/reachable), but that one script cannot cover the data shapes present in the rest of the test suite.

This patch introduces a new test environment variable, GIT_TEST_COMMIT_GRAPH . Similar to GIT_TEST_SPLIT_INDEX, it enables the commit-graph and writes it with every git commit command. Thanks, Duy, for pointing out this direction [1].

A few tests needed to be modified. These are the same tests that were mentioned in my previous example patch [2]. Thanks, Eric, for providing the correct way to override the settings [3].

When this merges down, I'll create a CI build in VSTS that runs the test suite with this option enabled.

Thanks, -Stolee

[1]
https://public-inbox.org/git/CACsJy8CKnXVJYkKM_W=N=Vq-TVXf+YCqZP_uP7B-dN_6xddB=g@mail.gmail.com/
Re: [PATCH 0/9] multi-pack-index cleanups (Discussing test environment variables)

[2]
https://public-inbox.org/git/[email protected]/
[PATCH] DO-NOT-MERGE: write and read commit-graph always

[3]
https://public-inbox.org/git/CAPig+cSjanDi=jV75PdzYpAjwVgd4Suh3UyvY+Vy7yeHAuY8RA@mail.gmail.com/

Based-On: ds/commit-graph-with-grafts Cc: [email protected]:
[email protected]: [email protected]

Derrick Stolee (1):
commit-graph: define GIT_TEST_COMMIT_GRAPH

 builtin/commit.c                    | 4 ++++
 commit-graph.c                      | 5 +++--
 commit-graph.h                      | 2 ++
 t/README                            | 4 ++++
 t/t0410-partial-clone.sh            | 2 +-
 t/t5307-pack-missing-commit.sh      | 4 ++--
 t/t6011-rev-list-with-bad-commit.sh | 7 +++----
 t/t6024-recursive-merge.sh          | 6 +++---
 8 files changed, 22 insertions(+), 12 deletions(-)

base-commit: 829a321569d8e8f2c582aef9f0c990df976ab842
Published-As: https://github.com/gitgitgadget/git/releases/tags/pr-26%2Fderrickstolee%2Fshallow%2Ftest-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-26/derrickstolee/shallow/test-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/26

Range-diff vs v1:

1: 85d02ac8d8 ! 1: 4ff6695c7e commit-graph: define GIT_TEST_COMMIT_GRAPH

     @@ -23,6 +23,7 @@
          merge-base algorithm picking one of two ambiguous merge-bases, and
          the commit-graph feature changes which merge-base is picked.
      
     +    Helped-by: Eric Sunshine <[email protected]>
          Signed-off-by: Derrick Stolee <[email protected]>
      
      diff --git a/builtin/commit.c b/builtin/commit.c
     @@ -112,18 +113,12 @@
       
       test_expect_success 'rev-list notices corruption (1)' '
      -	test_must_fail git rev-list HEAD
     -+	(
     -+		GIT_TEST_COMMIT_GRAPH=0 &&
     -+		test_must_fail git rev-list HEAD
     -+	)
     ++	test_must_fail env GIT_TEST_COMMIT_GRAPH=0 git rev-list HEAD
       '
       
       test_expect_success 'rev-list notices corruption (2)' '
      -	test_must_fail git rev-list --objects HEAD
     -+	(
     -+		GIT_TEST_COMMIT_GRAPH=0 &&
     -+		test_must_fail git rev-list --objects HEAD
     -+	)
     ++	test_must_fail env GIT_TEST_COMMIT_GRAPH=0 git rev-list --objects HEAD
       '
       
       test_expect_success 'pack-objects notices corruption' '
     @@ -140,10 +135,7 @@
      -   test_must_fail git rev-list --all > /dev/null
      -   '
      +test_expect_success 'rev-list should fail' '
     -+	(
     -+		GIT_TEST_COMMIT_GRAPH=0 &&
     -+		test_must_fail git rev-list --all > /dev/null
     -+	)
     ++	test_must_fail env GIT_TEST_COMMIT_GRAPH=0 git rev-list --all > /dev/null
      +'
       
       test_expect_success 'git repack _MUST_ fail' \
     @@ -160,10 +152,7 @@
      -	test_must_fail git merge -m final G
      -"
      +test_expect_success 'combined merge conflicts' '
     -+	(
     -+		GIT_TEST_COMMIT_GRAPH=0 &&
     -+		test_must_fail git merge -m final G
     -+	)
     ++	test_must_fail env GIT_TEST_COMMIT_GRAPH=0 git merge -m final G
      +'
       
       cat > expect << EOF

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