Merge pull request #10 from WindSoilder/master

Restrict type of `exc` in split function.

Author: njsmith

exceptiongroup/_tests/test_tools.py

@@ -1,3 +1,4 @@
+import pytest
 from exceptiongroup import ExceptionGroup, split
 
 
@@ -14,10 +15,9 @@ def raise_error_from_another(out_err, another_err):
         raise out_err from e
 
 
-def test_split_for_none_exception():
-    matched, unmatched = split(RuntimeError, None)
-    assert matched is None
-    assert unmatched is None
+def test_split_for_none_exception_should_raise_value_error():
+    with pytest.raises(TypeError):
+        matched, unmatched = split(RuntimeError, None)
 
 
 def test_split_when_all_exception_matched():

exceptiongroup/_tools.py

@@ -17,10 +17,15 @@ def split(exc_type, exc, *, match=None):
         match (None or func): predicate function to restict the split process,
             if the argument is not None, only exceptions with match(exception)
             will go into matched part.
+
+    Note that if the `exc` is type of ExceptionGroup, then the return
+    value will be tuple of (ExceptionGroup or None, ExceptionGroup or None)
     """
-    if exc is None:
-        return None, None
-    elif isinstance(exc, ExceptionGroup):
+    if not isinstance(exc, BaseException):
+        raise TypeError(
+            "Argument `exc` should be an instance of BaseException."
+        )
+    if isinstance(exc, ExceptionGroup):
         matches = []
         match_notes = []
         rests = []
@@ -38,13 +43,13 @@ def split(exc_type, exc, *, match=None):
         elif rests and not matches:
             return None, exc
         else:
-            match = copy.copy(exc)
-            match.exceptions = matches
-            match.sources = match_notes
-            rest = copy.copy(exc)
-            rest.exceptions = rests
-            rest.sources = rest_notes
-            return match, rest
+            matched_group = copy.copy(exc)
+            matched_group.exceptions = matches
+            matched_group.sources = match_notes
+            rest_group = copy.copy(exc)
+            rest_group.exceptions = rests
+            rest_group.sources = rest_notes
+            return matched_group, rest_group
     else:
         if isinstance(exc, exc_type) and (match is None or match(exc)):
             return exc, None