initial stab at the option

src/include/deepstate/DeepState.h

@@ -520,7 +520,11 @@ DeepState_RunSavedTestCase(struct DeepState_TestInfo *test, const char *dir,
   if (path == NULL) {
     DeepState_Abandon("Error allocating memory");
   }
-  snprintf(path, path_len, "%s/%s", dir, name);
+  if (strncmp(dir, "", strlen(dir)) != 0) {
+    snprintf(path, path_len, "%s/%s", dir, name);
+  } else {
+    snprintf(path, path_len, "%s", name);
+  }
 
   DeepState_InitInputFromFile(path);
 
@@ -587,11 +591,8 @@ static int DeepState_RunSavedCasesForTest(struct DeepState_TestInfo *test) {
   return num_failed_tests;
 }
 
-/* Run tests with saved input from `FLAGS_input_test_dir`.
- *
- * For each test unit and case, see if there are input files in the
- * expected directories. If so, use them to initialize
- * `DeepState_Input`, then run the test. If not, skip the test. */
+/* Run test from `FLAGS_input_test_file`, under `FLAGS_input_which_test`
+ * or first test, if not defined. */
 static int DeepState_RunSingleSavedTestCase(void) {
   int num_failed_tests = 0;
   struct DeepState_TestInfo *test = NULL;
@@ -599,7 +600,20 @@ static int DeepState_RunSingleSavedTestCase(void) {
   DeepState_Setup();
 
   for (test = DeepState_FirstTest(); test != NULL; test = test->prev) {
-    num_failed_tests += DeepState_RunSavedCasesForTest(test);
+    if (HAS_FLAG_input_which_test) {
+      if (strncmp(FLAGS_input_which_test, test->test_name, strlen(FLAGS_input_which_test)) == 0) {
+	break;
+      }
+    } else {
+      break;
+    }
+  }
+
+  enum DeepState_TestRunResult result =
+    DeepState_RunSavedTestCase(test, "", FLAGS_input_test_file);
+
+  if (result != DeepState_TestRunPass) {
+    num_failed_tests++;
   }
 
   DeepState_Teardown();