create session.items before preparse, so collectonly wont break on preparse fail, fixes #115

CHANGELOG

@@ -14,6 +14,8 @@ Changes between 2.2.1 and 2.2.2.dev
 - fix crash resulting from calling monkeypatch undo a second time
 - extend reports accepting kwargs to set arbitrary additional attributes
   this helps xdist serialization/deserialization of extended/customized reports
+- fix issue115: make --collectonly robust against preparse failure
+  (missing files/directories)
 
 Changes between 2.2.0 and 2.2.1
 ----------------------------------------

_pytest/main.py

@@ -410,6 +410,7 @@ class Session(FSCollector):
         self._notfound = []
         self._initialpaths = set()
         self._initialparts = []
+        self.items = items = []
         for arg in args:
             parts = self._parsearg(arg)
             self._initialparts.append(parts)
@@ -425,7 +426,6 @@ class Session(FSCollector):
         if not genitems:
             return rep.result
         else:
-            self.items = items = []
             if rep.passed:
                 for node in rep.result:
                     self.items.extend(self.genitems(node))

testing/test_terminal.py

@@ -256,6 +256,17 @@ class TestCollectonly:
             *1 error*
         """).strip())
 
+    def test_collectonly_missing_path(self, testdir):
+        """this checks issue 115,
+            failure in parseargs will cause session
+            not to have the items attribute
+        """
+        result = testdir.runpytest("--collectonly", "uhm_missing_path")
+        assert result.ret == 3
+        result.stderr.fnmatch_lines([
+            '*ERROR: file not found*',
+        ])
+
 
 def test_repr_python_version(monkeypatch):
     try: