[red-knot] Shorten the paths for some mdtest files (#14267)

crates/red_knot_python_semantic/resources/mdtest/with/sync.md

@@ -0,0 +1,141 @@
+# With statements
+
+## Basic `with` statement
+
+The type of the target variable in a `with` statement is the return type from the context manager's
+`__enter__` method.
+
+```py
+class Target: ...
+
+class Manager:
+    def __enter__(self) -> Target:
+        return Target()
+
+    def __exit__(self, exc_type, exc_value, traceback): ...
+
+with Manager() as f:
+    reveal_type(f)  # revealed: Target
+```
+
+## Union context manager
+
+```py
+def coinflip() -> bool:
+    return True
+
+class Manager1:
+    def __enter__(self) -> str:
+        return "foo"
+
+    def __exit__(self, exc_type, exc_value, traceback): ...
+
+class Manager2:
+    def __enter__(self) -> int:
+        return 42
+
+    def __exit__(self, exc_type, exc_value, traceback): ...
+
+context_expr = Manager1() if coinflip() else Manager2()
+
+with context_expr as f:
+    reveal_type(f)  # revealed: str | int
+```
+
+## Context manager without an `__enter__` or `__exit__` method
+
+```py
+class Manager: ...
+
+# error: [invalid-context-manager] "Object of type `Manager` cannot be used with `with` because it doesn't implement `__enter__` and `__exit__`"
+with Manager():
+    ...
+```
+
+## Context manager without an `__enter__` method
+
+```py
+class Manager:
+    def __exit__(self, exc_tpe, exc_value, traceback): ...
+
+# error: [invalid-context-manager] "Object of type `Manager` cannot be used with `with` because it doesn't implement `__enter__`"
+with Manager():
+    ...
+```
+
+## Context manager without an `__exit__` method
+
+```py
+class Manager:
+    def __enter__(self): ...
+
+# error: [invalid-context-manager] "Object of type `Manager` cannot be used with `with` because it doesn't implement `__exit__`"
+with Manager():
+    ...
+```
+
+## Context manager with non-callable `__enter__` attribute
+
+```py
+class Manager:
+    __enter__ = 42
+
+    def __exit__(self, exc_tpe, exc_value, traceback): ...
+
+# error: [invalid-context-manager] "Object of type `Manager` cannot be used with `with` because the method `__enter__` of type `Literal[42]` is not callable"
+with Manager():
+    ...
+```
+
+## Context manager with non-callable `__exit__` attribute
+
+```py
+class Manager:
+    def __enter__(self) -> Self: ...
+
+    __exit__ = 32
+
+# error: [invalid-context-manager] "Object of type `Manager` cannot be used with `with` because the method `__exit__` of type `Literal[32]` is not callable"
+with Manager():
+    ...
+```
+
+## Context expression with possibly-unbound union variants
+
+```py
+def coinflip() -> bool:
+    return True
+
+class Manager1:
+    def __enter__(self) -> str:
+        return "foo"
+
+    def __exit__(self, exc_type, exc_value, traceback): ...
+
+class NotAContextManager: ...
+
+context_expr = Manager1() if coinflip() else NotAContextManager()
+
+# error: [invalid-context-manager] "Object of type `Manager1 | NotAContextManager` cannot be used with `with` because the method `__enter__` is possibly unbound"
+# error: [invalid-context-manager] "Object of type `Manager1 | NotAContextManager` cannot be used with `with` because the method `__exit__` is possibly unbound"
+with context_expr as f:
+    reveal_type(f)  # revealed: str
+```
+
+## Context expression with "sometimes" callable `__enter__` method
+
+```py
+def coinflip() -> bool:
+    return True
+
+class Manager:
+    if coinflip():
+        def __enter__(self) -> str:
+            return "abcd"
+
+    def __exit__(self, *args): ...
+
+# error: [invalid-context-manager] "Object of type `Manager` cannot be used with `with` because the method `__enter__` is possibly unbound"
+with Manager() as f:
+    reveal_type(f)  # revealed: str
+```