summarize warning summaries if the number of locations is high

changelog/6834.feature.rst

@@ -0,0 +1 @@
+Excess warning summaries are now collapsed per file to ensure readable display of warning summaries.

src/_pytest/terminal.py

@@ -825,16 +825,32 @@ def summary_warnings(self):
             for wr in warning_reports:
                 reports_grouped_by_message.setdefault(wr.message, []).append(wr)
 
-            title = "warnings summary (final)" if final else "warnings summary"
-            self.write_sep("=", title, yellow=True, bold=False)
-            for message, warning_reports in reports_grouped_by_message.items():
-                has_any_location = False
+            def collapsed_location_report(reports: List[WarningReport]):
+                locations = []
                 for w in warning_reports:
                     location = w.get_location(self.config)
                     if location:
-                        self._tw.line(str(location))
-                        has_any_location = True
-                if has_any_location:
+                        locations.append(location)
+
+                if len(locations) < 10:
+                    return "\n".join(map(str, locations))
+
+                counts_by_filename = collections.Counter(
+                    str(loc).split("::", 1)[0] for loc in locations
+                )
+                return "\n".join(
+                    "{0}: {1} test{2} with warning{2}".format(
+                        k, v, "s" if v > 1 else ""
+                    )
+                    for k, v in counts_by_filename.items()
+                )
+
+            title = "warnings summary (final)" if final else "warnings summary"
+            self.write_sep("=", title, yellow=True, bold=False)
+            for message, warning_reports in reports_grouped_by_message.items():
+                maybe_location = collapsed_location_report(warning_reports)
+                if maybe_location:
+                    self._tw.line(maybe_location)
                     lines = message.splitlines()
                     indented = "\n".join("  " + x for x in lines)
                     message = indented.rstrip()

testing/example_scripts/warnings/test_group_warnings_by_message_summary.py

@@ -0,0 +1,21 @@
+import warnings
+
+import pytest
+
+
+def func():
+    warnings.warn(UserWarning("foo"))
+
+
+@pytest.fixture(params=range(20), autouse=True)
+def repeat_hack(request):
+    return request.param
+
+
+@pytest.mark.parametrize("i", range(5))
+def test_foo(i):
+    func()
+
+
+def test_bar():
+    func()

testing/test_warnings.py

@@ -584,6 +584,24 @@ def test_group_warnings_by_message(testdir):
     assert result.stdout.str().count(warning_code) == 1
 
 
+@pytest.mark.filterwarnings("ignore::pytest.PytestExperimentalApiWarning")
+@pytest.mark.filterwarnings("always")
+def test_group_warnings_by_message_summary(testdir):
+    testdir.copy_example("warnings/test_group_warnings_by_message_summary.py")
+    result = testdir.runpytest()
+    result.stdout.fnmatch_lines(
+        [
+            "*== %s ==*" % WARNINGS_SUMMARY_HEADER,
+            "test_group_warnings_by_message_summary.py: 120 tests with warnings",
+            "*test_group_warnings_by_message_summary.py:7: UserWarning: foo",
+        ],
+        consecutive=True,
+    )
+    warning_code = 'warnings.warn(UserWarning("foo"))'
+    assert warning_code in result.stdout.str()
+    assert result.stdout.str().count(warning_code) == 1
+
+
 def test_pytest_configure_warning(testdir, recwarn):
     """Issue 5115."""
     testdir.makeconftest(