1 files changed, 30 insertions, 0 deletions
diff --git a/Firestore/Source/Util/FSTUsageValidation.mm b/Firestore/Source/Util/FSTUsageValidation.mm
new file mode 100644
index 0000000..82128f4
--- /dev/null
+++ b/Firestore/Source/Util/FSTUsageValidation.mm
@@ -0,0 +1,30 @@
+/*
+ * Copyright 2017 Google
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+NSException *FSTInvalidUsage(NSString *exceptionName, NSString *format, ...) {
+  va_list arg_list;
+  va_start(arg_list, format);
+  NSString *formattedString = [[NSString alloc] initWithFormat:format arguments:arg_list];
+  va_end(arg_list);
+
+  return [[NSException alloc] initWithName:exceptionName reason:formattedString userInfo:nil];
+}
+
+NS_ASSUME_NONNULL_END