test-lib: respect GIT_TEST_INSTALLED when querying default hash

From: Kyle Lippincott <[email protected]>

$GIT_TEST_INSTALLED can be set to use an "installed" git instead of the one from $GIT_BUILD_DIR. This is used by my company's internal test infrastructure, and not using $GIT_TEST_INSTALLED when querying the default hash meant that the tests were failing because the hash was effectively set to the empty string (since git didn't execute).

In the two places we attempt to detect/execute git itself prior to overriding everything and putting it in $PATH, use identical logic for identifying the git binary to execute. This also has the effect of including the $X suffix when querying the default hash, but that's not strictly necessary. You don't need to specify .exe when running a binary on Windows, just when testing whether it exists or not.

---
test-lib: respect GIT_TEST_INSTALLED when querying default hash

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2011%2Fspectral54%2Fdefault_hash_respect_git_test_installed-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2011/spectral54/default_hash_respect_git_test_installed-v1
Pull-Request: https://github.com/git/git/pull/2011

 t/test-lib.sh | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

index 6dc2022ee10..621cd31ae1d 100644
@@ -134,7 +134,8 @@ export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
 ################################################################
 # It appears that people try to run tests without building...
-"${GIT_TEST_INSTALLED:-$GIT_BUILD_DIR}/git$X" >/dev/null
+GIT_BINARY="${GIT_TEST_INSTALLED:-$GIT_BUILD_DIR}/git$X"
+"$GIT_BINARY" >/dev/null
 if test $? != 1
 then
 	if test -n "$GIT_TEST_INSTALLED"

@@ -536,7 +537,7 @@ export GIT_COMMITTER_EMAIL GIT_COMMITTER_NAME
 export GIT_COMMITTER_DATE GIT_AUTHOR_DATE
 export EDITOR
 
-GIT_TEST_BUILTIN_HASH=$("$GIT_BUILD_DIR/git" version --build-options | sed -ne 's/^default-hash: //p')
+GIT_TEST_BUILTIN_HASH=$("$GIT_BINARY" version --build-options | sed -ne 's/^default-hash: //p')
 GIT_DEFAULT_HASH="${GIT_TEST_DEFAULT_HASH:-$GIT_TEST_BUILTIN_HASH}"
 export GIT_DEFAULT_HASH
 GIT_DEFAULT_REF_FORMAT="${GIT_TEST_DEFAULT_REF_FORMAT:-files}"

base-commit: e9779f64349fbcc8d177d055208039877316e652

gitgitgadget

The second paragraph was a little difficult for me to parse, but I understand the change as the following:

In c79bb70a2e (Enable SHA-256 by default in breaking changes mode, 2025-07-01), when building Git with WITH_BREAKING_CHANGES defined, the default object hash format is changed from SHA1 to SHA256. To select the correct hash used by GIT_TEST_BUILTIN_HASH during testing, git-version(1) is executed with the --build-options flag to get the default hash the Git binary is built with.

When running the Git testsuite with GIT_TEST_INSTALLED set, the Git binary in GIT_BUILD_DIR is used to check for the default hash which is incorrect. Instead the binary at GIT_TEST_INSTALLED should be used.