diff --git a/pykep/test.py b/pykep/test.py
index 77d2ec3..88605aa 100644
--- a/pykep/test.py
+++ b/pykep/test.py
@@ -8,7 +8,7 @@
 ## with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 import unittest as _ut
-from .test_trajopt import mga_tests
+from .test_trajopt import *
 
 def float_abs_error(a: float, b: float):
     return abs(a - b)
@@ -313,8 +313,9 @@ def run_test_suite():
     suite.addTest(propagate_test("test_stark"))
     suite.addTest(py_udplas_test("test_tle"))
     suite.addTest(py_udplas_test("test_spice"))
-    suite.addTest(mga_tests("test_construction"))
-    suite.addTest(mga_tests("test_encoding_to_encoding"))
+    suite.addTest(trajopt_mga_tests("test_construction"))
+    suite.addTest(trajopt_mga_tests("test_encoding_to_encoding"))
+    suite.addTest(gym_cassini1_tests("test_fitness"))
 
     suite.addTest(tl.loadTestsFromTestCase(vsop2013_test))
 
diff --git a/pykep/test_trajopt.py b/pykep/test_trajopt.py
index 6852efe..3dcc413 100644
--- a/pykep/test_trajopt.py
+++ b/pykep/test_trajopt.py
@@ -12,13 +12,10 @@
 
 import unittest as _ut
 
-def float_abs_error(a: float, b: float):
-    return abs(a - b)
-
 def float_rel_error(a: float, b: float):
     return abs(a - b) / abs(a)
 
-class mga_tests(_ut.TestCase):
+class trajopt_mga_tests(_ut.TestCase):
     def test_construction(self):
         import pykep as pk
         earth = pk.planet(pk.udpla.jpl_lp("earth"))
@@ -54,3 +51,20 @@ def test_encoding_to_encoding(self):
         self.assertTrue(float_rel_error(gt, udp_eta.fitness(x_eta)[0]) < 1e-14)
         self.assertTrue(float_rel_error(gt, udp_direct.fitness(udp_direct.alpha2direct(x_alpha))[0]) < 1e-14)
         self.assertTrue(float_rel_error(gt, udp_direct.fitness(udp_eta.eta2direct(x_eta))[0]) < 1e-14)
+
+class gym_cassini1_tests(_ut.TestCase):
+    def test_fitness(self):
+        import pykep as pk
+        udp = pk.trajopt.gym.cassini1
+        # Three random values. Ground truth provided by the old pykep code
+        x = [-554.5189290104555, 103.27184879471751, 335.41655259663474, 80.50258543604521, 862.0950563689543, 2865.018040480413  ]
+        f = udp.fitness(x)[0]
+        self.assertTrue(float_rel_error(f,80400.08897584089) < 1e-14)
+        
+        x = [-932.0532394941108, 37.534681289972674, 162.5093144821548, 336.970139545233, 1743.2915882004586, 2527.8785180526465  ]
+        f = udp.fitness(x)[0]
+        self.assertTrue(float_rel_error(f,217105.87501757513) < 1e-14)
+        
+        x = [-583.0776694390058, 388.65047998036107, 334.9959782156864, 65.57508619540917, 1520.2982946551908, 2132.7771932619144 ]
+        f = udp.fitness(x)[0]
+        self.assertTrue(float_rel_error(f,107218.0849582104) < 1e-14)
\ No newline at end of file