checks: add actionable assertion messages to advanced OOP checks

checks/oop_advanced/oop_advanced1.py

@@ -1,4 +1,5 @@
+# checks/oop_advanced/oop_advanced1.py
 dog = Dog()
-assert isinstance(dog, Animal)
-assert dog.speak() == "sound"
+assert isinstance(dog, Animal), "Dog() should be an instance of Animal"
+assert dog.speak() == "sound", "Dog().speak() should return 'sound'"
 print("oop_advanced1 ok")

checks/oop_advanced/oop_advanced2.py

@@ -1,4 +1,7 @@
+# checks/oop_advanced/oop_advanced2.py
 employee = Employee("Ada", "Engineer")
-assert employee.name == "Ada"
-assert employee.role == "Engineer"
+assert employee.name == "Ada", f"expected name 'Ada', got {employee.name!r}"
+assert employee.role == "Engineer", (
+    f"expected role 'Engineer', got {employee.role!r}"
+)
 print("oop_advanced2 ok")

checks/oop_advanced/oop_advanced3.py

@@ -1,3 +1,4 @@
+# checks/oop_advanced/oop_advanced3.py
 shapes = [Square(3), Rectangle(2, 5)]
-assert total_area(shapes) == 19
+assert total_area(shapes) == 19, "total_area(shapes) should be 19"
 print("oop_advanced3 ok")

checks/oop_advanced/oop_advanced4.py

@@ -1,3 +1,4 @@
+# checks/oop_advanced/oop_advanced4.py
 user = User("Lin")
-assert user.name == "Lin"
+assert user.name == "Lin", f"expected name 'Lin', got {user.name!r}"
 print("oop_advanced4 ok")

checks/oop_advanced/oop_advanced5.py

@@ -1,3 +1,4 @@
+# checks/oop_advanced/oop_advanced5.py
 playlist = Playlist(["one", "two", "three"])
-assert len(playlist) == 3
+assert len(playlist) == 3, "len(playlist) should be 3"
 print("oop_advanced5 ok")

checks/oop_advanced/oop_advanced6.py

@@ -1,2 +1,5 @@
-assert repr(Point(2, 5)) == "Point(x=2, y=5)"
+# checks/oop_advanced/oop_advanced6.py
+assert repr(Point(2, 5)) == "Point(x=2, y=5)", (
+    "repr(Point(2, 5)) should be 'Point(x=2, y=5)'"
+)
 print("oop_advanced6 ok")

tests/unit/test_check_namespaces.py

@@ -0,0 +1,21 @@
+# tests/unit/test_check_namespaces.py
+from pathlib import Path
+
+from solutions._answers import ANSWERS
+
+
+def test_area_check_preserves_learner_globals() -> None:
+    namespace = {"__name__": "__main__"}
+    exec(ANSWERS["oop_advanced3"], namespace)
+    namespace["area"] = 0
+    check = (
+        Path(__file__).resolve().parents[2]
+        / "checks" / "oop_advanced" / "oop_advanced3.py"
+    )
+
+    exec(
+        compile(check.read_text(encoding="utf-8"), str(check), "exec"),
+        namespace,
+    )
+
+    assert namespace["area"] == 0