From 23c43a37e0f98310a3bf6a679fcff40fe130c18f Mon Sep 17 00:00:00 2001
From: Ronny Pfannschmidt <ronny.pfannschmidt@redhat.com>
Date: Fri, 28 Feb 2020 10:33:59 +0100
Subject: [PATCH] summarize warning summaries if the number of locations is
 high

---
 changelog/6834.feature.rst                    |  1 +
 src/_pytest/terminal.py                       | 30 ++++++++++++++-----
 .../test_group_warnings_by_message_summary.py | 21 +++++++++++++
 testing/test_warnings.py                      | 18 +++++++++++
 4 files changed, 63 insertions(+), 7 deletions(-)
 create mode 100644 changelog/6834.feature.rst
 create mode 100644 testing/example_scripts/warnings/test_group_warnings_by_message_summary.py

diff --git a/changelog/6834.feature.rst b/changelog/6834.feature.rst
new file mode 100644
index 000000000..506814ef6
--- /dev/null
+++ b/changelog/6834.feature.rst
@@ -0,0 +1 @@
+Excess warning summaries are now collapsed per file to ensure readable display of warning summaries.
diff --git a/src/_pytest/terminal.py b/src/_pytest/terminal.py
index 4be5b8513..ed3576ed9 100644
--- a/src/_pytest/terminal.py
+++ b/src/_pytest/terminal.py
@@ -825,16 +825,32 @@ class TerminalReporter:
             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()
diff --git a/testing/example_scripts/warnings/test_group_warnings_by_message_summary.py b/testing/example_scripts/warnings/test_group_warnings_by_message_summary.py
new file mode 100644
index 000000000..4f7df3d6d
--- /dev/null
+++ b/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()
diff --git a/testing/test_warnings.py b/testing/test_warnings.py
index b05816073..5387c8d44 100644
--- a/testing/test_warnings.py
+++ b/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(