TST: implement testing for discretized encoding.

Author: phmbressan

tests/integration/test_encoding.py

@@ -228,3 +228,36 @@ def test_rocket_encoder(rocket_name, request):
         rocket_to_encode.static_margin(sample_times),
         rocket_loaded.static_margin(sample_times),
     )
+
+
+@pytest.mark.parametrize("rocket_name", ["calisto_robust"])
+def test_encoder_discretize(rocket_name, request):
+    """Test encoding the total mass of``rocketpy.Rocket`` with
+    discretized encoding.
+
+    Parameters
+    ----------
+    rocket_name : str
+        Name of the rocket fixture to encode.
+    request : pytest.FixtureRequest
+        Pytest request object.
+    """
+    rocket_to_encode = request.getfixturevalue(rocket_name)
+
+    json_encoded = json.dumps(
+        rocket_to_encode, cls=RocketPyEncoder, discretize=True, include_outputs=True
+    )
+
+    mass_loaded = json.loads(
+        json.dumps(json.loads(json_encoded)["total_mass"]), cls=RocketPyDecoder
+    )
+
+    sample_times = np.linspace(*rocket_to_encode.motor.burn_time, 100)
+
+    np.testing.assert_allclose(
+        mass_loaded(sample_times),
+        rocket_to_encode.total_mass(sample_times),
+        rtol=1e-3,
+        atol=1e-1,
+    )
+    assert isinstance(mass_loaded.source, np.ndarray)