Test if a draw function is a function in validate_draw_function (#74)

src/pySODM/models/base.py

@@ -755,7 +755,7 @@ def sim(self, time, warmup=0, N=1, draw_function=None, samples=None, processes=N
 
         # Provinding 'N' but no draw function: wastefull
         if ((N != 1) & (draw_function==None)):
-            raise ValueError('performing N={0} repeated simulations without a `draw_function` is mighty wastefull of computational resources'.format(N))
+            raise ValueError('performing N={0} repeated simulations without using a `draw_function` is wastefull of computational resources'.format(N))
 
         # Copy parameter dictionary --> dict is global
         cp = copy.deepcopy(self.parameters)

src/pySODM/models/validation.py

@@ -83,9 +83,14 @@ def validate_draw_function(draw_function, parameters, samples):
         an updated dictionary of model parameters
     """
 
+    # check if it is a function
+    if not callable(draw_function):
+        raise TypeError(
+            f"a 'draw function' must be callable (a function)"
+        )
+    # verify that names of draw function input args are 'parameters' and 'samples
     sig = inspect.signature(draw_function)
     keywords = list(sig.parameters.keys())
-    # Verify that names of draw function input args are 'parameters' and 'samples
     if len(keywords) != 2:
         raise ValueError(
             f"Your draw function '{draw_function.__name__}' must have 'parameters' and 'samples' as the names of its inputs. Its current inputs are named: {keywords}"
@@ -95,7 +100,7 @@ def validate_draw_function(draw_function, parameters, samples):
             raise ValueError(
             f"Your draw function '{draw_function.__name__}' must have 'parameters' and 'samples' as the names of its inputs. Its current inputs are named: {keywords}"
         )
-    # Call draw function
+    # call draw function and check its outputs
     cp_draws=copy.deepcopy(parameters)
     d = draw_function(parameters, samples)
     parameters = cp_draws

src/tests/test_JumpProcess.py

@@ -519,6 +519,12 @@ def draw_function(parameters, samples):
     # assert dimension 'draws' is present in output
     assert 'draws' in list(output.sizes.keys())
 
+    # wrong draw function: not a function
+    time = [0, 10]
+    model = SIRstratified(initial_states, parameters, coordinates=coordinates)
+    with pytest.raises(TypeError, match="a 'draw function' must be callable"):
+        model.sim(time, draw_function='bliblablu', samples={}, N=5)
+
     # wrong draw function: not enough input arguments
     def draw_function(parameters):
         return parameters

src/tests/test_ODE.py

@@ -500,6 +500,12 @@ def draw_function(parameters, samples):
     # assert dimension 'draws' is present in output
     assert 'draws' in list(output.sizes.keys())
 
+    # wrong draw function: not a function
+    time = [0, 10]
+    model = SIRstratified(initial_states, parameters, coordinates=coordinates)
+    with pytest.raises(TypeError, match="a 'draw function' must be callable"):
+        model.sim(time, draw_function='bliblablu', samples={}, N=5)
+
     # wrong draw function: not enough input arguments
     def draw_function(parameters):
         return parameters