t: invert `GIT_TEST_WRITE_REV_INDEX`

Back in e8c58f894b (t: support GIT_TEST_WRITE_REV_INDEX, 2021-01-25), we
added a test knob to conditionally enable writing a ".rev" file when
indexing a pack. At the time, this was used to ensure that the test
suite worked even when ".rev" files were written, which served as a
stress-test for the on-disk reverse index implementation.

Now that reading from on-disk ".rev" files is enabled by default, the
test knob `GIT_TEST_WRITE_REV_INDEX` no longer has any meaning.

We could get rid of the option entirely, but there would be no
convenient way to test Git when ".rev" files *aren't* in place.

Instead of getting rid of the option, invert its meaning to instead
disable writing ".rev" files, thereby running the test suite in a mode
where the reverse index is generated from scratch.

This ensures that, when GIT_TEST_NO_WRITE_REV_INDEX is set to some
spelling of "true", we are still running and exercising Git's behavior
when forced to generate reverse indexes from scratch. Do so by setting
it in the linux-TEST-vars CI run to ensure that we are maintaining good
coverage of this now-legacy code.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Acked-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/index-pack.c

@@ -1758,8 +1758,8 @@ int cmd_index_pack(int argc, const char **argv, const char *prefix)
 	if (prefix && chdir(prefix))
 		die(_("Cannot come back to cwd"));
 
-	if (git_env_bool(GIT_TEST_WRITE_REV_INDEX, 0))
-		rev_index = 1;
+	if (git_env_bool(GIT_TEST_NO_WRITE_REV_INDEX, 0))
+		rev_index = 0;
 	else
 		rev_index = !!(opts.flags & (WRITE_REV_VERIFY | WRITE_REV));
 

builtin/pack-objects.c

@@ -4295,8 +4295,8 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 	reset_pack_idx_option(&pack_idx_opts);
 	pack_idx_opts.flags |= WRITE_REV;
 	git_config(git_pack_config, NULL);
-	if (git_env_bool(GIT_TEST_WRITE_REV_INDEX, 0))
-		pack_idx_opts.flags |= WRITE_REV;
+	if (git_env_bool(GIT_TEST_NO_WRITE_REV_INDEX, 0))
+		pack_idx_opts.flags &= ~WRITE_REV;
 
 	progress = isatty(2);
 	argc = parse_options(argc, argv, prefix, pack_objects_options,

ci/run-build-and-tests.sh

@@ -27,7 +27,7 @@ linux-TEST-vars)
 	export GIT_TEST_MULTI_PACK_INDEX=1
 	export GIT_TEST_MULTI_PACK_INDEX_WRITE_BITMAP=1
 	export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=master
-	export GIT_TEST_WRITE_REV_INDEX=1
+	export GIT_TEST_NO_WRITE_REV_INDEX=1
 	export GIT_TEST_CHECKOUT_WORKERS=2
 	;;
 linux-clang)

pack-revindex.h

@@ -34,7 +34,7 @@
 #define RIDX_SIGNATURE 0x52494458 /* "RIDX" */
 #define RIDX_VERSION 1
 
-#define GIT_TEST_WRITE_REV_INDEX "GIT_TEST_WRITE_REV_INDEX"
+#define GIT_TEST_NO_WRITE_REV_INDEX "GIT_TEST_NO_WRITE_REV_INDEX"
 #define GIT_TEST_REV_INDEX_DIE_IN_MEMORY "GIT_TEST_REV_INDEX_DIE_IN_MEMORY"
 #define GIT_TEST_REV_INDEX_DIE_ON_DISK "GIT_TEST_REV_INDEX_DIE_ON_DISK"
 

t/README

@@ -475,7 +475,7 @@ GIT_TEST_DEFAULT_HASH=<hash-algo> specifies which hash algorithm to
 use in the test scripts. Recognized values for <hash-algo> are "sha1"
 and "sha256".
 
-GIT_TEST_WRITE_REV_INDEX=<boolean>, when true enables the
+GIT_TEST_NO_WRITE_REV_INDEX=<boolean>, when true disables the
 'pack.writeReverseIndex' setting.
 
 GIT_TEST_SPARSE_INDEX=<boolean>, when true enables index writes to use the

t/t5325-reverse-index.sh

@@ -7,7 +7,7 @@ TEST_PASSES_SANITIZE_LEAK=true
 
 # The below tests want control over the 'pack.writeReverseIndex' setting
 # themselves to assert various combinations of it with other options.
-sane_unset GIT_TEST_WRITE_REV_INDEX
+sane_unset GIT_TEST_NO_WRITE_REV_INDEX
 
 packdir=.git/objects/pack