Add testing of all core examples

Author: Corvince

examples/__init__.py

@@ -0,0 +1,33 @@
+import pytest
+import os
+from mesa import Model
+import importlib
+
+
+def get_models(directory):
+    models = []
+    for root, dirs, files in os.walk(directory):
+        for file in files:
+            if file == "model.py":
+                module_name = os.path.relpath(os.path.join(root, file[:-3])).replace(
+                    os.sep, "."
+                )
+
+                module = importlib.import_module(module_name)
+                for item in dir(module):
+                    obj = getattr(module, item)
+                    if (
+                        isinstance(obj, type)
+                        and issubclass(obj, Model)
+                        and obj is not Model
+                    ):
+                        models.append(obj)
+
+    return models
+
+
+@pytest.mark.parametrize("model_class", get_models("examples"))
+def test_model_steps(model_class):
+    model = model_class()  # Assume no arguments are needed
+    for _ in range(10):
+        model.step()