object: test looking up truncated objects

Add a test that looks up an invalid, truncated object, that is shorter
than the advertised length.

tests/libgit2/object/lookup.c

@@ -120,3 +120,14 @@ void test_object_lookup__lookup_object_with_wrong_hash_returns_error(void)
 	git_str_dispose(&oldpath);
 	git_str_dispose(&newpath);
 }
+
+void test_object_lookup__lookup_short_object_errors_gracefully(void)
+{
+	const char *invalid = "bf3d798a12d2bd09a73b1bbdec6fde6f9836f9ac";
+	git_object *object;
+	git_oid oid;
+
+	cl_git_pass(git_oid_from_string(&oid, invalid, GIT_OID_SHA1));
+
+	cl_git_fail(git_object_lookup(&object, g_repo, &oid, GIT_OBJECT_BLOB));
+}

tests/libgit2/odb/foreach.c

@@ -27,8 +27,8 @@ static int foreach_cb(const git_oid *oid, void *data)
 
 /*
  * $ git --git-dir tests/resources/testrepo.git count-objects --verbose
- * count: 60
- * size: 240
+ * count: 61
+ * size: 244
  * in-pack: 1640
  * packs: 3
  * size-pack: 425
@@ -43,7 +43,7 @@ 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(60 + 1640, nobj); /* count + in-pack */
+	cl_assert_equal_i(61 + 1640, nobj); /* count + in-pack */
 }
 
 void test_odb_foreach__one_pack(void)
@@ -144,7 +144,7 @@ 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(60 + 1640, nobj); /* count + in-pack */
+	cl_assert_equal_i(61 + 1640, nobj); /* count + in-pack */
 
 	git_odb_free(odb);
 	git_repository_free(repo);