factor out some common shared test init code
diff --git a/src/tests/test_common.h b/src/tests/test_common.h
new file mode 100644
index 0000000..1af1abd
--- /dev/null
+++ b/src/tests/test_common.h
@@ -0,0 +1,3 @@
+#pragma once
+
+int test_common_init(void);