revwalk: introduce tests that hide old commits

Introduce some tests that show some commits, while hiding some commits
that have a timestamp older than the common ancestors of these two
commits.

tests/odb/foreach.c

@@ -28,8 +28,8 @@ static int foreach_cb(const git_oid *oid, void *data)
 
 /*
  * $ git --git-dir tests/resources/testrepo.git count-objects --verbose
- * count: 47
- * size: 4
+ * count: 60
+ * size: 240
  * in-pack: 1640
  * packs: 3
  * size-pack: 425
@@ -44,7 +44,7 @@ void test_odb_foreach__foreach(void)
 	git_repository_odb(&_odb, _repo);
 
 	cl_git_pass(git_odb_foreach(_odb, foreach_cb, &nobj));
-	cl_assert_equal_i(47 + 1640, nobj); /* count + in-pack */
+	cl_assert_equal_i(60 + 1640, nobj); /* count + in-pack */
 }
 
 void test_odb_foreach__one_pack(void)
@@ -118,7 +118,7 @@ void test_odb_foreach__files_in_objects_dir(void)
 
 	cl_git_pass(git_repository_odb(&odb, repo));
 	cl_git_pass(git_odb_foreach(odb, foreach_cb, &nobj));
-	cl_assert_equal_i(47 + 1640, nobj); /* count + in-pack */
+	cl_assert_equal_i(60 + 1640, nobj); /* count + in-pack */
 
 	git_odb_free(odb);
 	git_repository_free(repo);

tests/revwalk/basic.c

@@ -473,3 +473,51 @@ void test_revwalk_basic__big_timestamp(void)
 	git_signature_free(sig);
 
 }
+
+/* Ensure that we correctly hide a commit that is (timewise) older
+ * than the commits that we are showing.
+ *
+ * % git rev-list 8e73b76..bd75801
+ * bd758010071961f28336333bc41e9c64c9a64866
+ */
+void test_revwalk_basic__old_hidden_commit_one(void)
+{
+	git_oid new_id, old_id, oid;
+
+	revwalk_basic_setup_walk("testrepo.git");
+
+	cl_git_pass(git_oid_fromstr(&new_id, "bd758010071961f28336333bc41e9c64c9a64866"));
+	cl_git_pass(git_revwalk_push(_walk, &new_id));
+
+	cl_git_pass(git_oid_fromstr(&old_id, "8e73b769e97678d684b809b163bebdae2911720f"));
+	cl_git_pass(git_revwalk_hide(_walk, &old_id));
+
+	cl_git_pass(git_revwalk_next(&oid, _walk));
+	cl_assert(!git_oid_streq(&oid, "bd758010071961f28336333bc41e9c64c9a64866"));
+
+	cl_git_fail_with(GIT_ITEROVER, git_revwalk_next(&oid, _walk));
+}
+
+/* Ensure that we correctly hide a commit that is (timewise) older
+ * than the commits that we are showing.
+ *
+ * % git rev-list bd75801 ^b91e763
+ * bd758010071961f28336333bc41e9c64c9a64866
+ */
+void test_revwalk_basic__old_hidden_commit_two(void)
+{
+	git_oid new_id, old_id, oid;
+
+	revwalk_basic_setup_walk("testrepo.git");
+
+	cl_git_pass(git_oid_fromstr(&new_id, "bd758010071961f28336333bc41e9c64c9a64866"));
+	cl_git_pass(git_revwalk_push(_walk, &new_id));
+
+	cl_git_pass(git_oid_fromstr(&old_id, "b91e763008b10db366442469339f90a2b8400d0a"));
+	cl_git_pass(git_revwalk_hide(_walk, &old_id));
+
+	cl_git_pass(git_revwalk_next(&oid, _walk));
+	cl_assert(!git_oid_streq(&oid, "bd758010071961f28336333bc41e9c64c9a64866"));
+
+	cl_git_fail_with(GIT_ITEROVER, git_revwalk_next(&oid, _walk));
+}