diff --git a/tests/test_kepler.py b/tests/test_kepler.py
index 91ae51f..da47d29 100644
--- a/tests/test_kepler.py
+++ b/tests/test_kepler.py
@@ -2,7 +2,9 @@
 """
 test keplerian ephemeride to ECEF conversion
 """
+import pytest
 import xarray
+from pytest import approx
 import georinex as gr
 from datetime import datetime, timedelta
 import numpy as np
@@ -38,9 +40,17 @@
 dat = xarray.Dataset(sv, attrs={'svtype': 'G'},
                      coords={'time': [time]})
 
-x, y, z = gr.keplerian2ecef(dat)
 
-print(x, y, z)
+def test_kepler():
+    x, y, z = gr.keplerian2ecef(dat)
 
-magerr = np.sqrt((x-xref)**2 + (y-yref)**2 + (z-zref)**2)
-print('error magnitude [meters]', magerr)
+    assert x == approx(xref,rel=1e-4)
+    assert y == approx(yref,rel=1e-4)
+    assert z == approx(zref,rel=1e-4)
+
+    magerr = np.sqrt((x-xref)**2 + (y-yref)**2 + (z-zref)**2)
+    print('error magnitude [meters]', magerr)
+
+
+if __name__ == '__main__':
+    pytest.main(['-x',__file__])
\ No newline at end of file