diff --git a/filterpy/gh/test_gh.py b/filterpy/gh/tests/test_gh.py
similarity index 98%
rename from filterpy/gh/test_gh.py
rename to filterpy/gh/tests/test_gh.py
index fda1585..15e6532 100644
--- a/filterpy/gh/test_gh.py
+++ b/filterpy/gh/tests/test_gh.py
@@ -126,7 +126,7 @@ def fx(x):
     plt.plot(zs)
 
 
-def foo():
+def test_GHFilterOrder():
     def fx(x):
         return 2*x+1
 
@@ -140,7 +140,6 @@ def fx(x):
 
         assert abs(f1.x[0]-f2.x) < 1.e-18
 
-foo()
 
 if __name__ == "__main__":
     optimal_test()
@@ -149,4 +148,6 @@ def fx(x):
     test_1d_array()
     test_2d_array()
 
+    test_GHFilterOrder()
+
     print('all passed')