add pytest for raised exceptions

src/lumicks/pyoptics/trapping/interface.py

@@ -222,6 +222,11 @@ def fields_focus(
         where the field needs to be evaluated. In that case, all vectors need to be of the same
         length.
 
+    Raises
+    ------
+    ValueError: raised when the immersion medium of the bead does not match the medium of the
+    objective.
+
     Returns
     -------
     Ex : np.ndarray
@@ -568,7 +573,6 @@ def forces_focus(
     bfp_sampling_n=31,
     num_orders=None,
     integration_orders=None,
-    verbose=False,
 ):
     """
     Calculate the forces on a bead in the focus of an arbitrary input
@@ -688,8 +692,6 @@ def absorbed_power_focus(
     -------
     Pabs : the absorbed power in Watts.
     """
-    if bead.n_medium != objective.n_medium:
-        raise ValueError("The immersion medium of the bead and the objective have to be the same")
 
     n_orders = bead.number_of_orders if num_orders is None else max(int(num_orders), 1)
 
@@ -796,9 +798,6 @@ def scattered_power_focus(
     Psca : the scattered power in Watts.
     """
 
-    if bead.n_medium != objective.n_medium:
-        raise ValueError("The immersion medium of the bead and the objective have to be the same")
-
     n_orders = bead.number_of_orders if num_orders is None else max(int(num_orders), 1)
 
     if integration_orders is None:

tests/trapping/test_trapping_api.py

@@ -0,0 +1,66 @@
+"""Test the czt-based implementation against a trivial implementation which sums plane waves"""
+
+import re
+
+import pytest
+
+import lumicks.pyoptics.trapping as trp
+
+bead_diam = 1e-6
+n_bead = 1.6
+n_medium = 1.33
+n_wrong_medium = 1.3
+NA = 1.2
+focal_length = 4.43e-3
+n_bfp = 1.0
+bead = trp.Bead(bead_diameter=bead_diam, n_bead=n_bead, n_medium=n_wrong_medium)
+objective = trp.Objective(NA=NA, focal_length=focal_length, n_bfp=n_bfp, n_medium=n_medium)
+
+
+def dummy(*args):
+    pass  # We should never get there
+
+
+## Test bead immersion medium and objective medium have to be the same
+@pytest.mark.parametrize(
+    "function",
+    [
+        trp.fields_focus,
+        trp.force_factory,
+    ],
+)
+def test_throw_on_wrong_medium(function) -> None:
+    bead = trp.Bead(bead_diameter=bead_diam, n_bead=n_bead, n_medium=n_wrong_medium)
+    objective = trp.Objective(NA=NA, focal_length=focal_length, n_bfp=n_bfp, n_medium=n_medium)
+    with pytest.raises(
+        ValueError,
+        match=re.escape("The immersion medium of the bead and the objective have to be the same"),
+    ):
+        function(dummy, objective=objective, bead=bead)
+
+
+@pytest.mark.parametrize(
+    "NA, focal_length, n_medium, n_bfp, error_msg",
+    [
+        (1.1, 4.43e-3, 1.0, 1.0, "The NA of the objective cannot be larger than n_medium"),
+        (
+            -1.9,
+            4.43e-3,
+            -1.0,
+            1.0,
+            "Only positive refractive indices are supported for n_bfp and n_medium",
+        ),
+        (
+            0.9,
+            4.43e-3,
+            1.0,
+            -1.0,
+            "Only positive refractive indices are supported for n_bfp and n_medium",
+        ),
+        (1.0, 0.0, 1.0, 1.0, "focal_length needs to be strictly positive"),
+        (0.0, 4.43e-3, 1.0, 1.0, "NA needs to be strictly positive"),
+    ],
+)
+def test_objective_value_errors(NA, focal_length, n_medium, n_bfp, error_msg):
+    with pytest.raises(ValueError, match=re.escape(error_msg)):
+        obj = trp.Objective(NA=NA, focal_length=focal_length, n_bfp=n_bfp, n_medium=n_medium)