last-failed: smarter collection

[blueyed]

With --lf it should not run a full collection, but use the information from the cache.

[nicoddemus]

diff --git a/src/_pytest/cacheprovider.py b/src/_pytest/cacheprovider.py
index ef2039539..2b76f9fff 100755
--- a/src/_pytest/cacheprovider.py
+++ b/src/_pytest/cacheprovider.py
@@ -159,6 +159,19 @@ class LFPlugin(object):
         self._previously_failed_count = None
         self._no_failures_behavior = self.config.getoption("last_failed_no_failures")

+    @property
+    def last_failed_paths(self):
+        result = getattr(self, '_last_failed_paths', None)
+        if result is None:
+            result = {Path(self.config.rootdir) / nodeid.split('::')[0] for nodeid in self.lastfailed}
+            self._last_failed_paths = result
+        return result
+
+    def pytest_ignore_collect(self, path):
+        if not self.active or not self.config.getoption("lf"):
+            return
+        return Path(path) not in self.last_failed_paths
+
     def pytest_report_collectionfinish(self):
         if self.active and self.config.getoption("verbose") >= 0:
             if not self._previously_failed_count:

Looks much easier than I thought... will open a PR later. 😁

[blueyed]

Awesome, thanks!