replace itertools.chain.from_iterable

Author: blueyed

doc/en/example/assertion/failure_demo.py

@@ -45,8 +45,7 @@ def test_eq_text(self):
         assert "spam" == "eggs"
 
     def test_eq_similar_text(self):
-        x = "foo\n1 bar\n"
-        assert x == "foo\n1 bar"
+        assert "foo 1 bar" == "foo 2 bar"
 
     def test_eq_multiline_text(self):
         assert "foo\nspam\nbar" == "foo\neggs\nbar"

src/_pytest/assertion/util.py

@@ -235,7 +235,7 @@ def _diff_text(left: str, right: str, verbose: int = 0) -> List[str]:
 
     if any(
         wcwidth(ch) <= 0
-        for ch in itertools.chain.from_iterable(x for x in left_lines + right_lines)
+        for ch in [ch for lines in left_lines + right_lines for ch in lines]
     ):
         left_lines = [repr(x) for x in left_lines]
         right_lines = [repr(x) for x in right_lines]