Add new parameter `choices` to Integer type

There is a need to add choices to PortOpt. So make Integer type accept
choices parameter first.
Choices options will provide a set of valid values. min/max provide a range
of values. They are mutally exclusive.

Change-Id: I0906b6e2309d751d7c31589fc3da8e5f3026bf64

2 files changed, 84 insertions, 11 deletions

diff --git a/oslo_config/tests/test_types.py b/oslo_config/tests/test_types.py
index 5f114c7..38e16e7 100644
--- a/oslo_config/tests/test_types.py
+++ b/oslo_config/tests/test_types.py
@@ -242,6 +242,10 @@ class IntegerTypeTests(TypeTestHelper, unittest.TestCase):
         t = types.Integer(min=0, max=0)
         self.assertEqual('Integer(min=0, max=0)', repr(t))
 
+    def test_repr_with_choices(self):
+        t = types.Integer(choices=[80, 457])
+        self.assertEqual('Integer(choices=[80, 457])', repr(t))
+
     def test_equal(self):
         self.assertTrue(types.Integer() == types.Integer())
 
@@ -256,12 +260,35 @@ class IntegerTypeTests(TypeTestHelper, unittest.TestCase):
         t2 = types.Integer(min=1, max=123)
         self.assertTrue(t1 == t2)
 
+    def test_equal_with_same_choices(self):
+        t1 = types.Integer(choices=[80, 457])
+        t2 = types.Integer(choices=[457, 80])
+        self.assertTrue(t1 == t2)
+
     def test_not_equal(self):
         self.assertFalse(types.Integer(min=123) == types.Integer(min=456))
+        self.assertFalse(types.Integer(choices=[80, 457]) ==
+                         types.Integer(choices=[80, 40]))
+        self.assertFalse(types.Integer(choices=[80, 457]) ==
+                         types.Integer())
 
     def test_not_equal_to_other_class(self):
         self.assertFalse(types.Integer() == types.String())
 
+    def test_choices_with_min_max(self):
+        self.assertRaises(ValueError,
+                          types.Integer,
+                          min=10,
+                          choices=[50, 60])
+        self.assertRaises(ValueError,
+                          types.Integer,
+                          max=100,
+                          choices=[50, 60])
+        self.assertRaises(ValueError,
+                          types.Integer,
+                          min=10, max=100,
+                          choices=[50, 60])
+
     def test_min_greater_max(self):
         self.assertRaises(ValueError,
                           types.Integer,
@@ -305,6 +332,22 @@ class IntegerTypeTests(TypeTestHelper, unittest.TestCase):
         self.assertRaises(ValueError, t, 201)
         self.assertRaises(ValueError, t, -457)
 
+    def test_with_choices_list(self):
+        t = types.Integer(choices=[80, 457])
+        self.assertRaises(ValueError, t, 1)
+        self.assertRaises(ValueError, t, 200)
+        self.assertRaises(ValueError, t, -457)
+        t(80)
+        t(457)
+
+    def test_with_choices_tuple(self):
+        t = types.Integer(choices=(80, 457))
+        self.assertRaises(ValueError, t, 1)
+        self.assertRaises(ValueError, t, 200)
+        self.assertRaises(ValueError, t, -457)
+        t(80)
+        t(457)
+
 
 class FloatTypeTests(TypeTestHelper, unittest.TestCase):
     type = types.Float()
diff --git a/oslo_config/types.py b/oslo_config/types.py
index 671272e..7d96ec0 100644
--- a/oslo_config/types.py
+++ b/oslo_config/types.py
@@ -192,23 +192,37 @@ class Integer(ConfigType):
     Converts value to an integer optionally doing range checking.
     If value is whitespace or empty string will return None.
 
-    :param min: Optional check that value is greater than or equal to min
-    :param max: Optional check that value is less than or equal to max
+    :param min: Optional check that value is greater than or equal to min.
+                Mutually exclusive with 'choices'.
+    :param max: Optional check that value is less than or equal to max.
+                Mutually exclusive with 'choices'.
     :param type_name: Type name to be used in the sample config file.
+    :param choices: Optional sequence of valid values. Mutually exclusive
+                    with 'min/max'.
 
     .. versionchanged:: 2.4
        The class now honors zero for *min* and *max* parameters.
 
     .. versionchanged:: 2.7
        Added *type_name* parameter.
+
+    .. versionchanged:: 3.2
+       Added *choices* parameter.
     """
 
-    def __init__(self, min=None, max=None, type_name='integer value'):
+    def __init__(self, min=None, max=None, type_name='integer value',
+                 choices=None):
         super(Integer, self).__init__(type_name=type_name)
+        if choices is not None:
+            if min is not None or max is not None:
+                raise ValueError("'choices' and 'min/max' cannot both be "
+                                 "specified")
+        else:
+            if min is not None and max is not None and max < min:
+                raise ValueError('Max value is less than min value')
         self.min = min
         self.max = max
-        if min is not None and max is not None and max < min:
-            raise ValueError('Max value is less than min value')
+        self.choices = choices
 
     def __call__(self, value):
         if not isinstance(value, int):
@@ -219,10 +233,20 @@ class Integer(ConfigType):
                 value = int(value)
 
         if value is not None:
-            self._check_range(value)
+            if self.choices is not None:
+                self._check_choices(value)
+            else:
+                self._check_range(value)
 
         return value
 
+    def _check_choices(self, value):
+        if value in self.choices:
+            return
+        else:
+            raise ValueError('Valid values are %r, but found %d' % (
+                             self.choices, value))
+
     def _check_range(self, value):
         if self.min is not None and value < self.min:
             raise ValueError('Should be greater than or equal to %d' %
@@ -232,10 +256,13 @@ class Integer(ConfigType):
 
     def __repr__(self):
         props = []
-        if self.min is not None:
-            props.append('min=%d' % self.min)
-        if self.max is not None:
-            props.append('max=%d' % self.max)
+        if self.choices is not None:
+            props.append("choices=%r" % (self.choices,))
+        else:
+            if self.min is not None:
+                props.append('min=%d' % self.min)
+            if self.max is not None:
+                props.append('max=%d' % self.max)
 
         if props:
             return 'Integer(%s)' % ', '.join(props)
@@ -245,7 +272,10 @@ class Integer(ConfigType):
         return (
             (self.__class__ == other.__class__) and
             (self.min == other.min) and
-            (self.max == other.max)
+            (self.max == other.max) and
+            (set(self.choices) == set(other.choices) if
+             self.choices and other.choices else
+             self.choices == other.choices)
         )