my.core: more work on typing @warn_if_empty, extra test

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