fix: show not_ prefix in call log when negative assertions fail (#3033)

Co-authored-by: Simon Knott <info@simonknott.de>

Author: scitech

playwright/_impl/_assertions.py

@@ -98,6 +98,8 @@ async def _expect_impl(
             expect_options["timeout"] = self._timeout or 5_000
         if expect_options["isNot"]:
             message = message.replace("expected to", "expected not to")
+            if title:
+                title = title.replace('"to_', '"not_to_')
         if "useInnerText" in expect_options and expect_options["useInnerText"] is None:
             del expect_options["useInnerText"]
         result = await self._call_expect(expression, expect_options, title)

tests/async/test_assertions.py

@@ -1024,6 +1024,15 @@ async def test_should_be_able_to_set_custom_timeout(page: Page) -> None:
     assert 'Expect "to_be_visible" with timeout 111ms' in str(exc_info.value)
 
 
+async def test_negative_assertion_shows_not_prefix_in_call_log(
+    page: Page,
+) -> None:
+    await page.set_content("<button>hello</button>")
+    with pytest.raises(AssertionError) as exc_info:
+        await expect(page.locator("button")).not_to_be_visible(timeout=111)
+    assert 'Expect "not_to_be_visible" with timeout 111ms' in str(exc_info.value)
+
+
 async def test_should_be_able_to_set_custom_global_timeout(page: Page) -> None:
     try:
         expect.set_options(timeout=111)