From 1c6fd0f505ca9ce6ed71ea44d92a97ec60a9befc Mon Sep 17 00:00:00 2001
From: Mike <mikewooster87@gmail.com>
Date: Thu, 15 Mar 2018 12:19:50 +0000
Subject: [PATCH] Add PositiveIntegerValue to only allow positive integers
 (#186)

---
 configurations/values.py |  9 +++++++++
 docs/values.rst          |  8 ++++++++
 tests/test_values.py     | 11 ++++++++++-
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/configurations/values.py b/configurations/values.py
index e5f4e2d..056e9a0 100644
--- a/configurations/values.py
+++ b/configurations/values.py
@@ -178,6 +178,15 @@ class IntegerValue(CastingMixin, Value):
     caster = int
 
 
+class PositiveIntegerValue(IntegerValue):
+
+    def to_python(self, value):
+        int_value = super(PositiveIntegerValue, self).to_python(value)
+        if int_value < 0:
+            raise ValueError(self.message.format(value))
+        return int_value
+
+
 class FloatValue(CastingMixin, Value):
     caster = float
 
diff --git a/docs/values.rst b/docs/values.rst
index 255880f..cf2e7bf 100644
--- a/docs/values.rst
+++ b/docs/values.rst
@@ -230,6 +230,14 @@ Type values
 
         MYSITE_CACHE_TIMEOUT = values.IntegerValue(3600)
 
+.. class:: PositiveIntegerValue
+
+    A :class:`~Value` subclass that handles positive integer values.
+
+    ::
+
+        MYSITE_WORKER_POOL = values.PositiveIntegerValue(8)
+
 .. class:: FloatValue
 
     A :class:`~Value` subclass that handles float values.
diff --git a/tests/test_values.py b/tests/test_values.py
index 0eb3f43..853b4be 100644
--- a/tests/test_values.py
+++ b/tests/test_values.py
@@ -16,7 +16,7 @@ from configurations.values import (Value, BooleanValue, IntegerValue,
                                    DatabaseURLValue, EmailURLValue,
                                    CacheURLValue, BackendsValue,
                                    CastingMixin, SearchURLValue,
-                                   setup_value)
+                                   setup_value, PositiveIntegerValue)
 
 
 @contextmanager
@@ -136,6 +136,15 @@ class ValueTests(TestCase):
         with env(DJANGO_TEST='noninteger'):
             self.assertRaises(ValueError, value.setup, 'TEST')
 
+    def test_positive_integer_values(self):
+        value = PositiveIntegerValue(1)
+        with env(DJANGO_TEST='2'):
+            self.assertEqual(value.setup('TEST'), 2)
+        with env(DJANGO_TEST='noninteger'):
+            self.assertRaises(ValueError, value.setup, 'TEST')
+        with env(DJANGO_TEST='-1'):
+            self.assertRaises(ValueError, value.setup, 'TEST')
+
     def test_float_values(self):
         value = FloatValue(1.0)
         with env(DJANGO_TEST='2.0'):