Delete Account: started adding unit tests

__mocks__/gatsby-plugin-firebase/constants/functions.js

@@ -0,0 +1,15 @@
+const deleteUserFunctionName = 'deleteUser';
+
+const defaultDelayInMilliseconds = 2000;
+
+class Functions {
+  static get deleteUserFunctionName() {
+    return deleteUserFunctionName;
+  }
+
+  static get defaultDelayInMilliseconds() {
+    return defaultDelayInMilliseconds;
+  }
+}
+
+export default Functions;