tests: Fix issue with validation of positive tests

Change-Id: I466487c9a53d2b5ea1e8aa1c312c97ef6d5bb581
diff --git a/tests/layer_validation_tests.cpp b/tests/layer_validation_tests.cpp
index 795fdee..2b81d27 100644
--- a/tests/layer_validation_tests.cpp
+++ b/tests/layer_validation_tests.cpp
@@ -172,6 +172,9 @@
                 // Return true to avoid calling layers/driver with this error.
                 // And don't erase the "" string, so it remains if another error is found.
                 result = VK_TRUE;
+                found_expected = true;
+                m_msgFound = VK_TRUE;
+                m_failure_message_strings.insert(errorString);
             } else if (errorString.find(desired_msg) != string::npos) {
                 found_expected = true;
                 m_failure_message_strings.insert(errorString);