remove unused test function

Author: CJ-Wright

tests/test_tools.py

@@ -15,9 +15,6 @@
 tests_dir = os.path.dirname(os.path.abspath(thisfile))
 testdata_dir = os.path.join(tests_dir, 'testdata')
 
-def testdata(filename):
-    return os.path.join(testdata_dir, filename)
-
 import diffpy.pdfmorph.tools as tools
 
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