Add utility to check if some string value can be 'casted' to true or false.

slapos/tests/util.py

@@ -26,13 +26,13 @@
 ##############################################################################
 import os
 import slapos.util
+from slapos.util import string_to_boolean
 import tempfile
 import unittest
 import shutil
 from pwd import getpwnam
 
-
-class TestMkdirP(unittest.TestCase):
+class TestUtil(unittest.TestCase):
   """
   Tests methods available in the slapos.util module.
   """
@@ -107,5 +107,26 @@ class TestMkdirP(unittest.TestCase):
 
     shutil.rmtree(root_slaptest)
 
+  def test_string_to_boolean_with_true_values(self):
+    """
+    Check that mkdir_p doesn't raise if directory already exist.
+    """
+    for value in ['true', 'True', 'TRUE']:
+      self.assertTrue(string_to_boolean(value))
+
+  def test_string_to_boolean_with_false_values(self):
+    """
+    Check that mkdir_p doesn't raise if directory already exist.
+    """
+    for value in ['false', 'False', 'False']:
+      self.assertFalse(string_to_boolean(value))
+
+  def test_string_to_boolean_with_incorrect_values(self):
+    """
+    Check that mkdir_p doesn't raise if directory already exist.
+    """
+    for value in [True, False, 1, '1', 't', 'tru', 'truelle', 'f', 'fals', 'falsey']:
+      self.assertRaises(ValueError, string_to_boolean, value)
+
 if __name__ == '__main__':
   unittest.main()

slapos/util.py

@@ -43,3 +43,24 @@ def parse_certificate_key_pair(html):
   key = html[k_start:k_end]
 
   return certificate, key
+
+
+def string_to_boolean(string):
+  """
+  Return True if the value of the "string" parameter can be parsed as True.
+  Return False if the value of the "string" parameter can be parsed as False.
+  Otherwise, Raise.
+
+  The parser is completely arbitrary, see code for actual implementation.
+  """
+  if not isinstance(string, str) and not isinstance(string, unicode):
+    raise ValueError('Given value is not a string.')
+  acceptable_true_values = ['true']
+  acceptable_false_values = ['false']
+  string = string.lower()
+  if string in acceptable_true_values:
+    return True
+  if string in acceptable_false_values:
+    return False
+  else:
+    raise ValueError('%s is neither True nor False.' % string)