test-reach: test reduce_heads

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

t/helper/test-reach.c

@@ -102,6 +102,10 @@ int cmd__reach(int ac, const char **av)
 		struct commit_list *list = get_merge_bases_many(A, X_nr, X_array);
 		printf("%s(A,X):\n", av[1]);
 		print_sorted_commit_ids(list);
+	} else if (!strcmp(av[1], "reduce_heads")) {
+		struct commit_list *list = reduce_heads(X);
+		printf("%s(X):\n", av[1]);
+		print_sorted_commit_ids(list);
 	}
 
 	exit(0);

t/t6600-test-reach.sh

@@ -138,4 +138,26 @@ test_expect_success 'get_merge_bases_many' '
 	test_three_modes get_merge_bases_many
 '
 
+test_expect_success 'reduce_heads' '
+	cat >input <<-\EOF &&
+	X:commit-1-10
+	X:commit-2-8
+	X:commit-3-6
+	X:commit-4-4
+	X:commit-1-7
+	X:commit-2-5
+	X:commit-3-3
+	X:commit-5-1
+	EOF
+	{
+		echo "reduce_heads(X):" &&
+		git rev-parse commit-5-1 \
+			      commit-4-4 \
+			      commit-3-6 \
+			      commit-2-8 \
+			      commit-1-10 | sort
+	} >expect &&
+	test_three_modes reduce_heads
+'
+
 test_done