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[PATCH 8/9] Allow specifying compatibility hash

From
brian m. carlson <sandals@crustytoothpaste.net>
Date
Sep 19, 2025, 01:09 UTC
Message-ID
<20250919010911.649831-9-sandals@crustytoothpaste.net>
In-Reply-To
<20250919010911.649831-1-sandals@crustytoothpaste.net>

We want to specify a compatibility hash for testing interactions for SHA-256 repositories where we have SHA-1 compatibility enabled. Allow the user to specify this scenario in the test suite by setting GIT_TEST_DEFAULT_HASH to "sha256:sha1".

Note that this will get passed into GIT_DEFAULT_HASH, which Git itself does not presently support. However, we will support this in a future commit.

Since we'll now want to know the value for a specific version, let's add the ability to specify either the storage hash (in this case, SHA-256) or the compatibility hash (SHA-1). We use a different value for the compatibility hash that will be enabled for all repositories (test_repo_compat_hash_algo) versus the one that is used individually in some tests (test_compat_hash_algo), since we want to still run those individual tests without requiring that the testsuite be run fully in a compatibility mode.

Finally, in this scenario, we can no longer rely on having broken objects work since we lack compatibility mappings to rewrite objects in the repository. Add a prerequisite, BROKEN_OBJECTS, that checks to see if creating deliberately broken objects is possible, so that we can disable these tests if not.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 t/test-lib-functions.sh | 9 +++++++--
 t/test-lib.sh           | 7 +++++++
 2 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index a28de7b19b..52d7759bf5 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -1708,11 +1708,16 @@ test_set_hash () {
 # Detect the hash algorithm in use.
 test_detect_hash () {
 	case "${GIT_TEST_DEFAULT_HASH:-$GIT_TEST_BUILTIN_HASH}" in
-	"sha256")
+	*:*)
+	    test_hash_algo="${GIT_TEST_DEFAULT_HASH%%:*}"
+	    test_compat_hash_algo="${GIT_TEST_DEFAULT_HASH##*:}"
+	    test_repo_compat_hash_algo="$test_compat_hash_algo"
+	    ;;
+	sha256)
 	    test_hash_algo=sha256
 	    test_compat_hash_algo=sha1
 	    ;;
-	*)
+	sha1)
 	    test_hash_algo=sha1
 	    test_compat_hash_algo=sha256
 	    ;;
diff --git a/t/test-lib.sh b/t/test-lib.sh
index 621cd31ae1..14c777e4e2 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -1917,6 +1917,13 @@ test_lazy_prereq DEFAULT_HASH_ALGORITHM '
 test_lazy_prereq DEFAULT_REPO_FORMAT '
 	test_have_prereq SHA1,REFFILES
 '
+# BROKEN_OBJECTS is a test if we can write deliberately broken objects and
+# expect them to work.  When running using SHA-256 mode with SHA-1
+# compatibility, we cannot write such objects because there's no SHA-1
+# compatibility value for a nonexistent object.
+test_lazy_prereq BROKEN_OBJECTS '
+	test -z "$test_repo_compat_hash_algo"
+'
 
 # Ensure that no test accidentally triggers a Git command
 # that runs the actual maintenance scheduler, affecting a user's
Previous: Junio C HamanoNext: Patrick Steinhardt
Message 17 of 67 in “SHA-1/SHA-256 interoperability, part 1”
  1. 0/9 SHA-1/SHA-256 interoperability, part 1brian m. carlson, Sep 19, 2025
  2. 3/9 docs: reflect actual double signature for tagsbrian m. carlson, Sep 19, 2025
  3. Junio C HamanoSep 19, 2025
  4. brian m. carlsonSep 20, 2025
  5. Junio C HamanoSep 20, 2025
  6. Patrick SteinhardtSep 24, 2025
  7. brian m. carlsonSep 25, 2025
  8. 1/9 docs: update pack index v3 formatbrian m. carlson, Sep 19, 2025
  9. Junio C HamanoSep 19, 2025
  10. brian m. carlsonSep 20, 2025
  11. Junio C HamanoSep 20, 2025
  12. Patrick SteinhardtSep 24, 2025
  13. brian m. carlsonSep 25, 2025
  14. 2/9 docs: update offset order for pack index v3brian m. carlson, Sep 19, 2025
  15. 4/9 docs: improve ambiguous areas of pack format documentationbrian m. carlson, Sep 19, 2025
  16. Junio C HamanoSep 19, 2025
  17. 8/9 Allow specifying compatibility hashbrian m. carlson, Sep 19, 2025
  18. Patrick SteinhardtSep 24, 2025
  19. brian m. carlsonSep 30, 2025
  20. 5/9 docs: add documentation for loose objectsbrian m. carlson, Sep 19, 2025
  21. Junio C HamanoSep 19, 2025
  22. Junio C HamanoSep 19, 2025
  23. brian m. carlsonSep 19, 2025
  24. Junio C HamanoSep 19, 2025
  25. Patrick SteinhardtSep 24, 2025
  26. brian m. carlsonSep 25, 2025
  27. Junio C HamanoSep 19, 2025
  28. Patrick SteinhardtSep 24, 2025
  29. brian m. carlsonSep 30, 2025
  30. 6/9 rev-parse: allow printing compatibility hashbrian m. carlson, Sep 19, 2025
  31. Junio C HamanoSep 19, 2025
  32. Patrick SteinhardtSep 24, 2025
  33. brian m. carlsonSep 25, 2025
  34. 7/9 fsck: consider gpgsig headers expected in tagsbrian m. carlson, Sep 19, 2025
  35. Junio C HamanoSep 19, 2025
  36. brian m. carlsonSep 22, 2025
  37. 9/9 t: add a prerequisite for a compatibility hashbrian m. carlson, Sep 19, 2025
  38. Patrick SteinhardtSep 24, 2025
  39. 0/9 SHA-1/SHA-256 interoperability, part 1brian m. carlson, Oct 2, 2025
  40. 1/9 docs: update pack index v3 formatbrian m. carlson, Oct 2, 2025
  41. Junio C HamanoOct 3, 2025
  42. 3/9 docs: reflect actual double signature for tagsbrian m. carlson, Oct 2, 2025
  43. 2/9 docs: update offset order for pack index v3brian m. carlson, Oct 2, 2025
  44. 4/9 docs: improve ambiguous areas of pack format documentationbrian m. carlson, Oct 2, 2025
  45. Junio C HamanoOct 3, 2025
  46. brian m. carlsonOct 3, 2025
  47. 5/9 docs: add documentation for loose objectsbrian m. carlson, Oct 2, 2025
  48. Junio C HamanoOct 3, 2025
  49. 7/9 fsck: consider gpgsig headers expected in tagsbrian m. carlson, Oct 2, 2025
  50. 6/9 rev-parse: allow printing compatibility hashbrian m. carlson, Oct 2, 2025
  51. 8/9 t: allow specifying compatibility hashbrian m. carlson, Oct 2, 2025
  52. Junio C HamanoOct 3, 2025
  53. brian m. carlsonOct 3, 2025
  54. 9/9 t1010: use BROKEN_OBJECTS prerequisitebrian m. carlson, Oct 2, 2025
  55. 0/9 SHA-1/SHA-256 interoperability, part 1brian m. carlson, Oct 9, 2025
  56. 3/9 docs: reflect actual double signature for tagsbrian m. carlson, Oct 9, 2025
  57. 4/9 docs: improve ambiguous areas of pack format documentationbrian m. carlson, Oct 9, 2025
  58. 2/9 docs: update offset order for pack index v3brian m. carlson, Oct 9, 2025
  59. 1/9 docs: update pack index v3 formatbrian m. carlson, Oct 9, 2025
  60. 5/9 docs: add documentation for loose objectsbrian m. carlson, Oct 9, 2025
  61. 6/9 rev-parse: allow printing compatibility hashbrian m. carlson, Oct 9, 2025
  62. 8/9 t: allow specifying compatibility hashbrian m. carlson, Oct 9, 2025
  63. 7/9 fsck: consider gpgsig headers expected in tagsbrian m. carlson, Oct 9, 2025
  64. 9/9 t1010: use BROKEN_OBJECTS prerequisitebrian m. carlson, Oct 9, 2025
  65. Junio C HamanoOct 13, 2025
  66. brian m. carlsonOct 13, 2025
  67. Patrick SteinhardtOct 14, 2025

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