Add a challenge: extreme-concatenate

Author: laike9m

challenges/extreme-concatenate/question.py

@@ -0,0 +1,47 @@
+"""
+TODO:
+
+Suppose there's a function `foo`, whose first parameter can be anything.
+
+You want to use `foo`, but want to restrict the first argument to be a `Person`.
+You cannot modify `foo`, so you decide to write a function `transform`,
+to transform `foo` into the function you want.
+"""
+
+
+class Person:
+    pass
+
+
+def transform(f):
+    def wrapper(value: Person, *args, **kwargs):
+        return f(value, *args, **kwargs)
+
+    return wrapper
+
+
+## End of your code ##
+def foo(value, mode: str) -> None:
+    pass
+
+
+foo_with_person = transform(foo)
+foo_with_person(Person(), "1")
+foo_with_person(Person(), mode="1")
+foo_with_person(1, "1")  # expect-type-error
+foo_with_person(Person(), 1)  # expect-type-error
+foo_with_person(Person(), "1", 2)  # expect-type-error
+
+
+def foo2(value, mode: str, *, maybe: bool) -> None:
+    pass
+
+
+foo_with_person = transform(foo2)
+foo_with_person(Person(), "1", maybe=True)
+foo_with_person(value=Person(), mode="1", maybe=True)
+foo_with_person(Person(), mode="1", maybe=True)
+foo_with_person(Person(), mode="1")  # expect-type-error
+foo_with_person(Person(), 1, maybe=True)  # expect-type-error
+foo_with_person(Person(), "1", maybe=1)  # expect-type-error
+foo_with_person(Person(), "1", True)  # expect-type-error

challenges/extreme-concatenate/solution.py

@@ -0,0 +1,49 @@
+"""
+TODO:
+
+Suppose there's a function `foo`, whose first parameter can be anything.
+
+You want to use `foo`, but want to restrict the first argument to be a `Person`.
+You cannot modify `foo`, so you decide to write a function `transform`,
+to transform `foo` into the function you want.
+"""
+
+from typing import Concatenate, Callable, Any
+
+
+class Person:
+    pass
+
+
+def transform[T, **P](f: Callable[Concatenate[Any, P], T]):
+    def wrapper(value: Person, *args: P.args, **kwargs: P.kwargs) -> T:
+        return f(value, *args, **kwargs)
+
+    return wrapper
+
+
+## End of your code ##
+def foo(value, mode: str) -> None:
+    pass
+
+
+foo_with_person = transform(foo)
+foo_with_person(Person(), "1")
+foo_with_person(Person(), mode="1")
+foo_with_person(1, "1")  # expect-type-error
+foo_with_person(Person(), 1)  # expect-type-error
+foo_with_person(Person(), "1", 2)  # expect-type-error
+
+
+def foo2(value, mode: str, *, maybe: bool) -> int:
+    return 1
+
+
+foo_with_person = transform(foo2)
+foo_with_person(Person(), "1", maybe=True)
+foo_with_person(value=Person(), mode="1", maybe=True)
+foo_with_person(Person(), mode="1", maybe=True)
+foo_with_person(Person(), mode="1")  # expect-type-error
+foo_with_person(Person(), 1, maybe=True)  # expect-type-error
+foo_with_person(Person(), "1", maybe=1)  # expect-type-error
+foo_with_person(Person(), "1", True)  # expect-type-error

templates/challenge.html

@@ -239,7 +239,7 @@
         <p class="challenge-header__exerpt">
           Complete code following the instructions, so that lines followed by
           <code># expect-type-error</code> (if any)
-          should fail type check, others should pass.<br>
+          fail type check, while others can pass.<br>
           Hit the "▶️ Run" button to see result.
         </p>
       </div>

tests/test_api.py

@@ -4,6 +4,7 @@
 
 from views.challenge import ChallengeKey, Level, challenge_manager
 
+
 def test_get_challenge(test_client: FlaskClient, question_file: Path):
     level, challenge_name = question_file.parent.name.split("-", maxsplit=1)
     response = test_client.get(f"/{level}/{challenge_name}")