CI: don't run "make test" twice in one job

The "linux-clang" and "linux-gcc" jobs both run "make test" twice, but
with different environment variables. Running these in sequence seems
to have been done to work around some constraint on Travis, see
ae59a4e44f (travis: run tests with GIT_TEST_SPLIT_INDEX, 2018-01-07).

By having these run in parallel we'll get jobs that finish much sooner
than they otherwise would have.

We can also simplify the control flow in "ci/run-build-and-tests.sh"
as a result, since we won't run "make test" twice we don't need to run
"make" twice at all, let's default to "make all test" after setting
the variables, and then override it to just "all" for the compile-only
tests.

Add a comment to clarify that new "test" targets should adjust
$MAKE_TARGETS rather than being added after the "case/esac". This
should avoid future confusion where e.g. the compilation-only
"pedantic" target will unexpectedly start running tests. See [1] and
[2].

1. https://lore.kernel.org/git/211122.86ee78yxts.gmgdl@evledraar.gmail.com/
2. https://lore.kernel.org/git/211123.86ilwjujmd.gmgdl@evledraar.gmail.com/

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

.github/workflows/main.yml

@@ -225,10 +225,19 @@ jobs:
           - jobname: linux-clang
             cc: clang
             pool: ubuntu-latest
+          - jobname: linux-sha256
+            cc: clang
+            os: ubuntu
+            pool: ubuntu-latest
           - jobname: linux-gcc
             cc: gcc
             cc_package: gcc-8
             pool: ubuntu-latest
+          - jobname: linux-TEST-vars
+            cc: gcc
+            os: ubuntu
+            cc_package: gcc-8
+            pool: ubuntu-latest
           - jobname: osx-clang
             cc: clang
             pool: macos-latest

ci/run-build-and-tests.sh

@@ -10,16 +10,13 @@ windows*) cmd //c mklink //j t\\.prove "$(cygpath -aw "$cache_dir/.prove")";;
 *) ln -s "$cache_dir/.prove" t/.prove;;
 esac
 
-if test "$jobname" = "pedantic"
-then
-	export DEVOPTS=pedantic
-fi
+export MAKE_TARGETS="all test"
 
-make
 case "$jobname" in
 linux-gcc)
 	export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
-	make test
+	;;
+linux-TEST-vars)
 	export GIT_TEST_SPLIT_INDEX=yes
 	export GIT_TEST_MERGE_ALGORITHM=recursive
 	export GIT_TEST_FULL_IN_PACK_ARRAY=true
@@ -33,23 +30,25 @@ linux-gcc)
 	export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=master
 	export GIT_TEST_WRITE_REV_INDEX=1
 	export GIT_TEST_CHECKOUT_WORKERS=2
-	make test
 	;;
 linux-clang)
 	export GIT_TEST_DEFAULT_HASH=sha1
-	make test
+	;;
+linux-sha256)
 	export GIT_TEST_DEFAULT_HASH=sha256
-	make test
 	;;
 pedantic)
 	# Don't run the tests; we only care about whether Git can be
 	# built.
-	;;
-*)
-	make test
+	export DEVOPTS=pedantic
+	export MAKE_TARGETS=all
 	;;
 esac
 
+# Any new "test" targets should not go after this "make", but should
+# adjust $MAKE_TARGETS. Otherwise compilation-only targets above will
+# start running tests.
+make $MAKE_TARGETS
 check_unignored_build_artifacts
 
 save_good_tree