diff --git a/testing/test_collection.py b/testing/test_collection.py
index <HASH>..<HASH> 100644
--- a/testing/test_collection.py
+++ b/testing/test_collection.py
@@ -281,7 +281,7 @@ class TestPrunetraceback(object):
                 outcome = yield
                 rep = outcome.get_result()
                 rep.headerlines += ["header1"]
-                outcome.set_result(rep)
+                outcome.force_result(rep)
         """)
         result = testdir.runpytest(p)
         result.stdout.fnmatch_lines([
Fix call to outcome.force_result

Even though the test is not running at the moment (xfail), at least
we avoid future confusion