Merge pull request #1784 from mboutet/fix-html-download

Ensure that the exception dictionaries are not mutated when generating a html report

locust/html.py

@@ -35,10 +35,9 @@ def get_html_report(environment, show_download_link=True):
 
     requests_statistics = list(chain(sort_stats(stats.entries), [stats.total]))
     failures_statistics = sort_stats(stats.errors)
-    exceptions_statistics = []
-    for exc in environment.runner.exceptions.values():
-        exc["nodes"] = ", ".join(exc["nodes"])
-        exceptions_statistics.append(exc)
+    exceptions_statistics = [
+        {**exc, "nodes": ", ".join(exc["nodes"])} for exc in environment.runner.exceptions.values()
+    ]
 
     history = stats.history
 

locust/test/test_web.py

@@ -356,6 +356,14 @@ def test_report_exceptions(self):
         # self.assertEqual(200, r.status_code)
         self.assertIn("<h2>Exceptions Statistics</h2>", r.text)
 
+        # Prior to 088a98bf8ff4035a0de3becc8cd4e887d618af53, the "nodes" field for each exception in
+        # "self.runner.exceptions" was accidentally mutated in "get_html_report" to a string.
+        # This assertion reproduces the issue and it is left there to make sure there's no
+        # regression in the future.
+        self.assertTrue(
+            isinstance(next(iter(self.runner.exceptions.values()))["nodes"], set), "exception object has been mutated"
+        )
+
 
 class TestWebUIAuth(LocustTestCase):
     def setUp(self):