Add method check_string_length

This method exists in Nova[1] and Cinder[2], and it seems other
projects can also leverage it.

[1]http://git.openstack.org/cgit/openstack/nova/tree/nova/utils.py#n1088
[2]http://git.openstack.org/cgit/openstack/cinder/tree/cinder/utils.py#n676

Change-Id: I2e595404b564dbd363af545945a6bde37f70a4c2

2 files changed, 66 insertions, 0 deletions

diff --git a/oslo_utils/strutils.py b/oslo_utils/strutils.py
index 3fb3efa..ff3d43c 100644
--- a/oslo_utils/strutils.py
+++ b/oslo_utils/strutils.py
@@ -373,3 +373,35 @@ def is_int_like(val):
         return six.text_type(int(val)) == six.text_type(val)
     except (TypeError, ValueError):
         return False
+
+
+def check_string_length(value, name=None, min_length=0, max_length=None):
+    """Check the length of specified string.
+
+    :param value: the value of the string
+    :param name: the name of the string
+    :param min_length: the min_length of the string
+    :param max_length: the max_length of the string
+    :raises TypeError, ValueError: For any invalid input.
+
+    .. versionadded:: 3.7
+    """
+    if name is None:
+        name = value
+
+    if not isinstance(value, six.string_types):
+        msg = _("%s is not a string or unicode") % name
+        raise TypeError(msg)
+
+    length = len(value)
+    if length < min_length:
+        msg = _("%(name)s has %(length)s characters, less than "
+                "%(min_length)s.") % {'name': name, 'length': length,
+                                      'min_length': min_length}
+        raise ValueError(msg)
+
+    if max_length and length > max_length:
+        msg = _("%(name)s has %(length)s characters, more than "
+                "%(max_length)s.") % {'name': name, 'length': length,
+                                      'max_length': max_length}
+        raise ValueError(msg)
diff --git a/oslo_utils/tests/test_strutils.py b/oslo_utils/tests/test_strutils.py
index eba10c9..51aad0a 100644
--- a/oslo_utils/tests/test_strutils.py
+++ b/oslo_utils/tests/test_strutils.py
@@ -660,3 +660,37 @@ class IsIntLikeTestCase(test_base.BaseTestCase):
         # NOTE(viktors): Check integer numbers with base not 10
         self.assertFalse(strutils.is_int_like("0o51"))
         self.assertFalse(strutils.is_int_like("0xDEADBEEF"))
+
+
+class StringLengthTestCase(test_base.BaseTestCase):
+    def test_check_string_length(self):
+        self.assertIsNone(strutils.check_string_length(
+                          'test', 'name', max_length=255))
+        self.assertRaises(ValueError,
+                          strutils.check_string_length,
+                          '', 'name', min_length=1)
+        self.assertRaises(ValueError,
+                          strutils.check_string_length,
+                          'a' * 256, 'name', max_length=255)
+        self.assertRaises(TypeError,
+                          strutils.check_string_length,
+                          11, 'name', max_length=255)
+        self.assertRaises(TypeError,
+                          strutils.check_string_length,
+                          dict(), 'name', max_length=255)
+
+    def test_check_string_length_noname(self):
+        self.assertIsNone(strutils.check_string_length(
+                          'test', max_length=255))
+        self.assertRaises(ValueError,
+                          strutils.check_string_length,
+                          '', min_length=1)
+        self.assertRaises(ValueError,
+                          strutils.check_string_length,
+                          'a' * 256, max_length=255)
+        self.assertRaises(TypeError,
+                          strutils.check_string_length,
+                          11, max_length=255)
+        self.assertRaises(TypeError,
+                          strutils.check_string_length,
+                          dict(), max_length=255)