Add FuzzyDate

Signed-off-by: Raphaël Barrois <raphael.barrois@polytechnique.org>

3 files changed, 108 insertions, 0 deletions

diff --git a/docs/fuzzy.rst b/docs/fuzzy.rst
index f1f4085..7d56995 100644
--- a/docs/fuzzy.rst
+++ b/docs/fuzzy.rst
@@ -70,6 +70,33 @@ FuzzyInteger
         int, the inclusive higher bound of generated integers
 
 
+FuzzyDate
+---------
+
+.. class:: FuzzyDate(start_date[, end_date])
+
+    The :class:`FuzzyDate` fuzzer generates random dates within a given
+    inclusive range.
+
+    The :attr:`end_date` bound may be omitted, in which case it defaults to the current date:
+
+    .. code-block:: pycon
+
+        >>> fd = FuzzyDate(datetime.date(2008, 1, 1))
+        >>> fd.start_date, fd.end_date
+        datetime.date(2008, 1, 1), datetime.date(2013, 4, 16)
+
+    .. attribute:: start_date
+
+        :class:`datetime.date`, the inclusive lower bound of generated dates
+
+    .. attribute:: end_date
+
+        :class:`datetime.date`, the inclusive higher bound of generated dates
+
+        int, the inclusive higher bound of generated dates
+
+
 Custom fuzzy fields
 -------------------
 
diff --git a/factory/fuzzy.py b/factory/fuzzy.py
index 186b4a7..fea7b05 100644
--- a/factory/fuzzy.py
+++ b/factory/fuzzy.py
@@ -25,6 +25,7 @@
 
 
 import random
+import datetime
 
 from . import declarations
 
@@ -84,3 +85,22 @@ class FuzzyInteger(BaseFuzzyAttribute):
 
     def fuzz(self):
         return random.randint(self.low, self.high)
+
+
+class FuzzyDate(BaseFuzzyAttribute):
+    """Random date within a given date range."""
+    def __init__(self, start_date, end_date=None, **kwargs):
+        super(FuzzyDate, self).__init__(**kwargs)
+        if end_date is None:
+            end_date = datetime.date.today()
+
+        if start_date > end_date:
+            raise ValueError(
+                "FuzzyDate boundaries should have start <= end; got %r > %r."
+                % (start_date, end_date))
+
+        self.start_date = start_date.toordinal()
+        self.end_date = end_date.toordinal()
+
+    def fuzz(self):
+        return datetime.date.fromordinal(random.randint(self.start_date, self.end_date))
diff --git a/tests/test_fuzzy.py b/tests/test_fuzzy.py
index 70a2095..e3b5772 100644
--- a/tests/test_fuzzy.py
+++ b/tests/test_fuzzy.py
@@ -21,6 +21,8 @@
 # THE SOFTWARE.
 
 
+import datetime
+
 from factory import fuzzy
 
 from .compat import mock, unittest
@@ -102,3 +104,62 @@ class FuzzyIntegerTestCase(unittest.TestCase):
             res = fuzz.evaluate(2, None, False)
 
         self.assertEqual(8, res)
+
+
+class FuzzyDateTestCase(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        # Setup useful constants
+        cls.jan1 = datetime.date(2013, 1, 1)
+        cls.jan3 = datetime.date(2013, 1, 3)
+        cls.jan31 = datetime.date(2013, 1, 31)
+
+    def test_accurate_definition(self):
+        """Tests all ways of defining a FuzzyDate."""
+        fuzz = fuzzy.FuzzyDate(self.jan1, self.jan31)
+
+        for _i in range(20):
+            res = fuzz.evaluate(2, None, False)
+            self.assertLessEqual(self.jan1, res)
+            self.assertLessEqual(res, self.jan31)
+
+    def test_partial_definition(self):
+        """Test defining a FuzzyDate without passing an end date."""
+        with utils.mocked_date_today(self.jan3, fuzzy):
+            fuzz = fuzzy.FuzzyDate(self.jan1)
+
+        for _i in range(20):
+            res = fuzz.evaluate(2, None, False)
+            self.assertLessEqual(self.jan1, res)
+            self.assertLessEqual(res, self.jan3)
+
+    def test_invalid_definition(self):
+        self.assertRaises(ValueError, fuzzy.FuzzyDate,
+            self.jan31, self.jan1)
+
+    def test_invalid_partial_definition(self):
+        with utils.mocked_date_today(self.jan1, fuzzy):
+            self.assertRaises(ValueError, fuzzy.FuzzyDate,
+                self.jan31)
+
+    def test_biased(self):
+        """Tests a FuzzyDate with a biased random.randint."""
+
+        fake_randint = lambda low, high: (low + high) // 2
+        fuzz = fuzzy.FuzzyDate(self.jan1, self.jan31)
+
+        with mock.patch('random.randint', fake_randint):
+            res = fuzz.evaluate(2, None, False)
+
+        self.assertEqual(datetime.date(2013, 1, 16), res)
+
+    def test_biased_partial(self):
+        """Tests a FuzzyDate with a biased random and implicit upper bound."""
+        with utils.mocked_date_today(self.jan3, fuzzy):
+            fuzz = fuzzy.FuzzyDate(self.jan1)
+
+        fake_randint = lambda low, high: (low + high) // 2
+        with mock.patch('random.randint', fake_randint):
+            res = fuzz.evaluate(2, None, False)
+
+        self.assertEqual(datetime.date(2013, 1, 2), res)