Prefer security file over username/password (#21)

Use security file option if it is not empty.

README.rst

@@ -10,7 +10,7 @@ StorOps: The Python Library for VNX & Unity
 .. image:: https://img.shields.io/pypi/v/storops.svg
     :target: https://pypi.python.org/pypi/storops
 
-VERSION: 0.2.18
+VERSION: 0.2.19
 
 A minimalist Python library to manage VNX/Unity systems.
 This document lies in the source code and go with the release.
@@ -312,6 +312,8 @@ EMC Contributors
 Community Contributors
 ``````````````````````
 
+- Paulo Matias <matias@ufscar.br>
+
 Patches and Suggestions
 ```````````````````````
 

storops/vnx/navi_command.py

@@ -77,12 +77,11 @@ def is_credential_valid(self):
         return self._is_credential_valid
 
     def get_credentials(self):
-        if self._username is None and self._password is None:
+        if self._sec_file is not None:
             # use security file
-            if self._sec_file is not None:
-                ret = text_var('-secfilepath', self._sec_file)
-            else:
-                ret = []
+            ret = text_var('-secfilepath', self._sec_file)
+        elif self._username is None and self._password is None:
+            ret = []
         elif self._username is None or self._password is None:
             self._is_credential_valid = False
             raise ex.VNXCredentialError('username or password missing.')

test/vnx/test_navi_command.py

@@ -44,6 +44,13 @@ def test_security_file(self):
         assert_that(' '.join(cmd.get_credentials()),
                     equal_to('-secfilepath /a/b/c.key'))
 
+    @patch_cli
+    def test_security_file_precedence(self):
+        cmd = NaviCommand(sec_file=r'/a/b/c.key',
+                          username='admin', password='')
+        assert_that(' '.join(cmd.get_credentials()),
+                    equal_to('-secfilepath /a/b/c.key'))
+
     @patch_cli
     def test_username_password_timeout(self):
         cmd = NaviCommand('a', 'a', 1, timeout=20)