Add the tests that went with the changes.

cara/tests/models/test_concentration_model.py

@@ -0,0 +1,59 @@
+import numpy as np
+import pytest
+
+import cara.models
+
+
+@pytest.mark.parametrize(
+    "override_params", [
+        {'volume': np.array([100, 120])},
+        {'air_change': np.array([100, 120])},
+        {'virus_halflife': np.array([1.1, 1.5])},
+        {'viral_load_in_sputum': np.array([5e8, 1e9])},
+        {'coefficient_of_infectivity': np.array([0.02, 0.05])},
+        {'η_exhale': np.array([0.92, 0.95])},
+        {'η_leaks': np.array([0.15, 0.20])},
+
+    ]
+)
+def test_concentration_model_vectorisation(override_params):
+    defaults = {
+        'volume': 75,
+        'air_change': 100,
+        'virus_halflife': 1.1,
+        'viral_load_in_sputum': 1e9,
+        'coefficient_of_infectivity': 0.02,
+        'η_exhale': 0.95,
+        'η_leaks': 0.15,
+    }
+    defaults.update(override_params)
+
+    always = cara.models.PeriodicInterval(240, 240)  # TODO: This should be a thing on an interval.
+    c_model = cara.models.ConcentrationModel(
+        cara.models.Room(defaults['volume']),
+        cara.models.AirChange(always, defaults['air_change']),
+        cara.models.InfectedPopulation(
+            number=1,
+            presence=always,
+            mask=cara.models.Mask(
+                η_exhale=defaults['η_exhale'],
+                η_leaks=defaults['η_leaks'],
+                η_inhale=0.3,
+            ),
+            activity=cara.models.Activity(
+                0.51,
+                0.75,
+            ),
+            virus=cara.models.Virus(
+                halflife=defaults['virus_halflife'],
+                viral_load_in_sputum=defaults['viral_load_in_sputum'],
+                coefficient_of_infectivity=defaults['coefficient_of_infectivity'],
+            ),
+            expiration=cara.models.Expiration(
+                ejection_factor=(0.084, 0.009, 0.003, 0.002),
+            ),
+        )
+    )
+    concentrations = c_model.concentration(10)
+    assert isinstance(concentrations, np.ndarray)
+    assert concentrations.shape == (2, )