[disk] handle multilines df output (#2733)

When moving the disk check outside of `checks/`, `_is_number` method was
forgotten.
This is now fixed and a test is added.

Author: degemer

checks.d/disk.py

@@ -250,7 +250,7 @@ def _flatten_devices(self, devices):
         for parts in devices:
             if len(parts) == 1:
                 previous = parts[0]
-            elif previous and self._is_number(parts[0]):
+            elif previous is not None:
                 # collate with previous line
                 parts.insert(0, previous)
                 previous = None

tests/checks/fixtures/disk/centos-df-Tk

@@ -0,0 +1,6 @@
+Filesystem Type   1K-blocks   Used      Available  Use%  Mounted on
+/dev/sda3  ext4   93421512    70963180  17706052   81%   /
+tmpfs      tmpfs  32969616    0         32969616   0%    /dev/shm
+/dev/sda1  ext4   512752      90460     395412     19%   /boot
+10.1.5.223:/vil/cor
+           nfs     1020054752 56080768  963973984  6%    /cor

tests/checks/mock/test_disk.py

@@ -168,6 +168,20 @@ def test_no_psutil_freebsd(self, mock_df_output, mock_statvfs):
 
         self.coverage_report()
 
+    @mock.patch('utils.subprocess_output.get_subprocess_output',
+                return_value=(Fixtures.read_file('centos-df-Tk'), "", 0))
+    @mock.patch('os.statvfs', return_value=MockInodesMetrics())
+    def test_no_psutil_centos(self, mock_df_output, mock_statvfs):
+        self.run_check({'instances': [{'use_mount': 'no',
+                                       'excluded_filesystems': ['devfs', 'tmpfs'],
+                                       'excluded_disks': ['/dev/sda1']}]},
+                       mocks={'_psutil': lambda: False})
+        for device in ['/dev/sda3', '10.1.5.223:/vil/cor']:
+            for metric, _ in self.GAUGES_VALUES.iteritems():
+                self.assertMetric(metric, tags=[], device_name=device)
+
+        self.coverage_report()
+
     def test_legacy_option(self):
         # First, let's check that it actually retrieves from the agent config
         self.load_check({'instances': [{}]}, agent_config={'use_mount': 'yes'})