From e3a71ea6c68ee4c2564a97da8a4fec7e0b55c172 Mon Sep 17 00:00:00 2001
From: Dima Gerasimov <karlicoss@gmail.com>
Date: Sun, 24 May 2020 23:42:57 +0100
Subject: [PATCH] my.core: more work on typing @warn_if_empty, extra test

---
 my/core/common.py | 25 +++++++++++--------------
 tests/misc.py     | 26 ++++++++++++++++++++++----
 2 files changed, 33 insertions(+), 18 deletions(-)

diff --git a/my/core/common.py b/my/core/common.py
index 16a730b..30c2cf0 100644
--- a/my/core/common.py
+++ b/my/core/common.py
@@ -273,6 +273,7 @@ def get_valid_filename(s: str) -> str:
 from typing import Generic, Sized, Callable
 
 
+# X = TypeVar('X')
 def _warn_iterator(it):
     emitted = False
     for i in it:
@@ -281,27 +282,23 @@ def _warn_iterator(it):
     if not emitted:
         warnings.warn(f"Function hasn't emitted any data, make sure your config paths are correct")
 
-
-def _warn_iterable(it):
+# todo need to popretly restrict to a container... ugh
+C = TypeVar('C')
+def _warn_iterable(it: C) -> C:
     if isinstance(it, Sized):
         sz = len(it)
         if sz == 0:
             warnings.warn(f"Function is returning empty container, make sure your config paths are correct")
-        return it
+        return it # type: ignore[return-value]
     else:
         return _warn_iterator(it)
 
 
-from functools import wraps
-X = TypeVar('X')
-
-class G(Generic[X], Iterable[X]):
-    pass
-
-CC = Callable[[], G]
+CC = TypeVar('CC')
 def warn_if_empty(f: CC) -> CC:
-    @wraps(f)
-    def wrapped(*args, **kwargs) -> G[X]:
-        res = f(*args, **kwargs)
+    from functools import wraps
+    @wraps(f) # type: ignore[arg-type]
+    def wrapped(*args, **kwargs):
+        res = f(*args, **kwargs) # type: ignore[call-arg, operator]
         return _warn_iterable(res)
-    return wrapped
+    return wrapped # type: ignore[return-value]
diff --git a/tests/misc.py b/tests/misc.py
index a20399e..d425196 100644
--- a/tests/misc.py
+++ b/tests/misc.py
@@ -53,20 +53,38 @@ from my.core.error import test_sort_res_by
 from typing import Iterable, List
 import warnings
 from my.core import warn_if_empty
-def test_warn_if_empty():
-
+def test_warn_if_empty() -> None:
     @warn_if_empty
     def nonempty() -> Iterable[str]:
         yield 'a'
         yield 'aba'
 
     @warn_if_empty
-    def empty(arg: str) -> List[str]:
+    def empty() -> List[str]:
         return []
 
     with warnings.catch_warnings(record=True) as w:
         assert list(nonempty()) == ['a', 'aba']
         assert len(w) == 0
 
-        assert empty('whatever') == []
+        eee = empty()
+        assert eee == []
         assert len(w) == 1
+
+
+def test_warn_iterable() -> None:
+    from my.core.common import _warn_iterable
+    i1: List[str] = ['a', 'b']
+    i2: Iterable[int] = iter([1, 2, 3])
+    # reveal_type(i1)
+    # reveal_type(i2)
+    x1 = _warn_iterable(i1)
+    x2 = _warn_iterable(i2)
+    # reveal_type(x1)
+    # reveal_type(x2)
+    with warnings.catch_warnings(record=True) as w:
+        assert x1 is i1 # should be unchanged!
+        assert len(w) == 0
+
+        assert list(x2) == [1, 2, 3]
+        assert len(w) == 0