Add a basic trajectory test

lib/trajectory.py

@@ -38,10 +38,17 @@ def from_ca_frames(data, topology_attr={}):
     def __init__(self, mda_universe):
         self.mda_universe = mda_universe
 
+    @property
+    def coordinates(self):
+        return self.mda_universe.atoms.positions
+
     @property
     def frames(self):
         return self.mda_universe.trajectory
 
+    def __next__(self):
+        return next(self.mda_universe.trajectory)
+
     def select_atoms(self, *args):
         return self.mda_universe.select_atoms(*args)
 

tests/trajectory_test.py

@@ -0,0 +1,22 @@
+import unittest
+
+from lib.trajectory import Trajectory
+
+class TrajectoryTest(unittest.TestCase):
+    def test_basic(self):
+        coordinates1 = [[1, 2, 3], [4, 5, 6]]
+        coordinates2 = [[2, 3, 4], [3, 4, 5]]
+
+        trajectory = Trajectory.from_ca_frames(
+            [coordinates1, coordinates2]
+        )
+
+        self.assertEqual(len(trajectory.frames), 2)
+
+        self.assertEqual(trajectory.coordinates.tolist(), coordinates1)
+        next(trajectory)
+        self.assertEqual(trajectory.coordinates.tolist(), coordinates2)
+
+
+if __name__ == '__main__':
+    unittest.main()