TST: enable warnings in our test script

Author: pavoljuhas

src/diffpy/pdfgui/tests/run.py

@@ -21,6 +21,12 @@
 
 if __name__ == '__main__':
     import sys
+    # show warnings by default
+    if not sys.warnoptions:
+        import os, warnings
+        warnings.simplefilter("default")
+        # also affect subprocesses
+        os.environ["PYTHONWARNINGS"] = "default"
     from diffpy.pdfgui.tests import test
     # produce zero exit code for a successful test
     sys.exit(not test().wasSuccessful())