[PATCH 2/2] test-lib: GIT_TEST_ONLY to run only specific tests

[Ilya Bobyr <ilya.bobyr@gmail.com>]

This is a counterpart to GIT_SKIP_TESTS.  Mostly useful when debugging.
---
 t/README      |   15 +++++++++++++++
 t/test-lib.sh |    8 ++++++++
 2 files changed, 23 insertions(+), 0 deletions(-)

diff --git a/t/README b/t/README
index caeeb9d..f939987 100644
--- a/t/README
+++ b/t/README
@@ -187,6 +187,21 @@ and either can match the "t[0-9]{4}" part to skip the whole
 test, or t[0-9]{4} followed by ".$number" to say which
 particular test to skip.
 
+Sometimes the opposite is desired - ability to execute only one or
+several tests.  Mostly while debugging tests.  For that you can say
+
+    $ GIT_TEST_ONLY=t9200.8 sh ./t9200-git-cvsexport-commit.sh
+
+or, similrary to GIT_SKIP_TESTS
+
+    $ GIT_TEST_ONLY='t[0-4]??? t91?? t9200.8' make
+
+In additiona to matching against "<test suite number>.<test number>"
+GIT_TEST_ONLY is matched against just the test numbes.  This comes
+handy when you are running only one test:
+
+    $ GIT_TEST_ONLY='[0-8]' sh ./t9200-git-cvsexport-commit.sh
+
 Note that some tests in the existing test suite rely on previous
 test item, so you cannot arbitrarily disable one and expect the
 remainder of test to check what the test originally was intended
diff --git a/t/test-lib.sh b/t/test-lib.sh
index 89a405b..12bf436 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -464,6 +464,14 @@ test_skip () {
 		fi
 		skipped_reason="missing $missing_prereq${of_prereq}"
 	fi
+	if test -z "$to_skip" && test -n "$GIT_TEST_ONLY" &&
+		! match_pattern_list $this_test.$test_count $GIT_TEST_ONLY &&
+		! match_pattern_list $test_count $GIT_TEST_ONLY
+	then
+		to_skip=t
+		skipped_reason="not in GIT_TEST_ONLY"
+	fi
+
 	case "$to_skip" in
 	t)
 		say_color skip >&3 "skipping test: $@"
-- 
1.7.9