Merge pull request #1048 from RonnyPfannschmidt/pytest-1029

fixes #1029 by handling access errors for cache dirs as pytest warning

CHANGELOG

@@ -15,6 +15,7 @@
 - fix issue 877: properly handle assertion explanations with non-ascii repr
   Thanks Mathieu Agopian for the report and Ronny Pfannschmidt for the PR.
 
+- fix issue 1029: transform errors when writing cache values into pytest-warnings
 
 2.8.0
 -----------------------------

_pytest/cacheprovider.py

@@ -69,10 +69,22 @@ class Cache(object):
                like e. g. lists of dictionaries.
         """
         path = self._getvaluepath(key)
-        path.dirpath().ensure_dir()
-        with path.open("w") as f:
-            self.trace("cache-write %s: %r" % (key, value,))
-            json.dump(value, f, indent=2, sort_keys=True)
+        try:
+            path.dirpath().ensure_dir()
+        except (py.error.EEXIST, py.error.EACCES):
+            self.config.warn(
+                code='I9', message='could not create cache path %s' % (path,)
+            )
+            return
+        try:
+            f = path.open('w')
+        except py.error.ENOTDIR:
+            self.config.warn(
+                code='I9', message='cache could not write path %s' % (path,))
+        else:
+            with f:
+                self.trace("cache-write %s: %r" % (key, value,))
+                json.dump(value, f, indent=2, sort_keys=True)
 
 
 class LFPlugin:

testing/test_cache.py

@@ -1,3 +1,4 @@
+import sys
 import pytest
 import os
 import shutil
@@ -25,6 +26,36 @@ class TestNewAPI:
         val = config.cache.get("key/name", -2)
         assert val == -2
 
+    def test_cache_writefail_cachfile_silent(self, testdir):
+        testdir.makeini("[pytest]")
+        testdir.tmpdir.join('.cache').write('gone wrong')
+        config = testdir.parseconfigure()
+        cache = config.cache
+        cache.set('test/broken', [])
+
+    @pytest.mark.skipif(sys.platform.startswith('win'), reason='no chmod on windows')
+    def test_cache_writefail_permissions(self, testdir):
+        testdir.makeini("[pytest]")
+        testdir.tmpdir.ensure_dir('.cache').chmod(0)
+        config = testdir.parseconfigure()
+        cache = config.cache
+        cache.set('test/broken', [])
+
+    @pytest.mark.skipif(sys.platform.startswith('win'), reason='no chmod on windows')
+    def test_cache_failure_warns(self, testdir):
+        testdir.tmpdir.ensure_dir('.cache').chmod(0)
+        testdir.makepyfile("""
+            def test_pass():
+                pass
+
+        """)
+        result = testdir.runpytest('-rw')
+        assert result.ret == 0
+        result.stdout.fnmatch_lines([
+            "*could not create cache path*",
+            "*1 pytest-warnings*",
+        ])
+
     def test_config_cache(self, testdir):
         testdir.makeconftest("""
             def pytest_configure(config):