ensure failure to inject user files results in startup error

This was the case in Essex but was inadvertantly changed in:
folsom-2-95-g0d166ca.

* nova/virt/disk/api.py: Refactor to allow specifying
mandatory injection items, that result in an exception
on failure to inject.
* nova/virt/libvirt/driver.py: Specify that user 'files'
are mandatory items and thus result in VM startup failure
unless injected successfully.
* nova/tests/test_virt_disk.py: A new test for the
separate warning and error cases.

Fixes bug: 1095744
Change-Id: Idab5c4294c1cb52098ce44a7aae957a44fb2674f

nova/tests/test_virt_disk.py

@@ -14,8 +14,10 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import os
 import sys
 
+from nova import exception
 from nova import test
 from nova.tests import fakeguestfs
 from nova.virt.disk import api as diskapi
@@ -29,6 +31,25 @@ class VirtDiskTest(test.TestCase):
         sys.modules['guestfs'] = fakeguestfs
         vfsguestfs.guestfs = fakeguestfs
 
+    def test_inject_data(self):
+
+        self.assertTrue(diskapi.inject_data("/some/file", use_cow=True))
+
+        self.assertTrue(diskapi.inject_data("/some/file",
+                                            mandatory=('files',)))
+
+        self.assertTrue(diskapi.inject_data("/some/file", key="mysshkey",
+                                            mandatory=('key',)))
+
+        os_name = os.name
+        os.name = 'nt'  # Cause password injection to fail
+        self.assertRaises(exception.NovaException,
+                          diskapi.inject_data,
+                          "/some/file", admin_password="p",
+                          mandatory=('admin_password',))
+        self.assertFalse(diskapi.inject_data("/some/file", admin_password="p"))
+        os.name = os_name
+
     def test_inject_data_key(self):
 
         vfs = vfsguestfs.VFSGuestFS("/some/file", "qcow2")