Add an include guard to tests/base/functions.h.

Not important, but found while playing with collating testcases into
one.

diff --git a/tests/base/functions.h b/tests/base/functions.h
index db407ee75cd496c6915ffbccf0b471c950c5a790..580d632d38d1c3b508b4d74b7ee10de9c38ca272 100644 (file)
--- a/tests/base/functions.h
+++ b/tests/base/functions.h
@@ -15,6 +15,8 @@
 
 // Generic routines to check consistency of function classes
 
+#ifndef __TESTS_FUNCTIONS_H
+#define __TESTS_FUNCTIONS_H
 
 // Check, whether the various implementations of function values are
 // consistent. Arguments include the function, the amount of
@@ -230,3 +232,4 @@ check_gradient(
   deallog << std::endl;
 }
 
+#endif