test-reach: test get_reachable_subset

The get_reachable_subset() method returns the list of commits in
the 'to' array that are reachable from at least one commit in the
'from' array. Add tests that check this method works in a few
cases:

1. All commits in the 'to' list are reachable. This exercises the
   early-termination condition.

2. Some commits in the 'to' list are reachable. This exercises the
   loop-termination condition.

3. No commits in the 'to' list are reachable. This exercises the
   NULL return condition.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/t/t6600-test-reach.sh b/t/t6600-test-reach.sh
index ae94b27f70..a0c64e617a 100755
--- a/t/t6600-test-reach.sh
+++ b/t/t6600-test-reach.sh
@@ -265,4 +265,56 @@ test_expect_success 'commit_contains:miss' '
 	test_three_modes commit_contains --tag
 '
 
+test_expect_success 'get_reachable_subset:all' '
+	cat >input <<-\EOF &&
+	X:commit-9-1
+	X:commit-8-3
+	X:commit-7-5
+	X:commit-6-6
+	X:commit-1-7
+	Y:commit-3-3
+	Y:commit-1-7
+	Y:commit-5-6
+	EOF
+	(
+		echo "get_reachable_subset(X,Y)" &&
+		git rev-parse commit-3-3 \
+			      commit-1-7 \
+			      commit-5-6 | sort
+	) >expect &&
+	test_three_modes get_reachable_subset
+'
+
+test_expect_success 'get_reachable_subset:some' '
+	cat >input <<-\EOF &&
+	X:commit-9-1
+	X:commit-8-3
+	X:commit-7-5
+	X:commit-1-7
+	Y:commit-3-3
+	Y:commit-1-7
+	Y:commit-5-6
+	EOF
+	(
+		echo "get_reachable_subset(X,Y)" &&
+		git rev-parse commit-3-3 \
+			      commit-1-7 | sort
+	) >expect &&
+	test_three_modes get_reachable_subset
+'
+
+test_expect_success 'get_reachable_subset:none' '
+	cat >input <<-\EOF &&
+	X:commit-9-1
+	X:commit-8-3
+	X:commit-7-5
+	X:commit-1-7
+	Y:commit-9-3
+	Y:commit-7-6
+	Y:commit-2-8
+	EOF
+	echo "get_reachable_subset(X,Y)" >expect &&
+	test_three_modes get_reachable_subset
+'
+
 test_done