[experimental] cacheprovider: store repr of reports with last-failed (#55)

This is meant to aid debugging, e.g. in case there are suddenly a lot of
last-failed tests.

Ref: pytest-dev#5301
Ref: #54

Author: blueyed

src/_pytest/cacheprovider.py

@@ -191,7 +191,12 @@ def pytest_runtest_logreport(self, report):
         if (report.when == "call" and report.passed) or report.skipped:
             self.lastfailed.pop(report.nodeid, None)
         elif report.failed:
-            self.lastfailed[report.nodeid] = True
+            info = [repr(report)]
+            try:
+                info.append(str(report.longrepr.reprcrash))
+            except AttributeError:
+                info.append(str(report.longrepr))
+            self.lastfailed[report.nodeid] = info
 
     def pytest_collectreport(self, report):
         passed = report.outcome in ("passed", "skipped")