Use repr to encode floats in to_bytes

This ensures that no precision is lost when encoding 64-bit floats. This
matches the encoding logic in redis-py. Tests are added for `set`,
`incrbyfloat` and `hincrbyfloat`.

fakeredis.py

@@ -41,6 +41,8 @@
     def to_bytes(x, charset=DEFAULT_ENCODING, errors='strict'):
         if isinstance(x, unicode):
             return x.encode(charset, errors)
+        if isinstance(x, float):
+            return repr(x)
         if isinstance(x, (bytes, bytearray, buffer)) or hasattr(x, '__str__'):
             return bytes(x)
         if hasattr(x, '__unicode__'):
@@ -76,6 +78,8 @@ def to_bytes(x, charset=sys.getdefaultencoding(), errors='strict'):
             return bytes(x)
         if isinstance(x, str):
             return x.encode(charset, errors)
+        if isinstance(x, float):
+            return repr(x).encode(charset, errors)
         if hasattr(x, '__str__'):
             return str(x).encode(charset, errors)
         raise TypeError('expected bytes or str, not ' + type(x).__name__)

test_fakeredis.py

@@ -104,6 +104,11 @@ def test_set_None_value(self):
         self.assertEqual(self.redis.set('foo', None), True)
         self.assertEqual(self.redis.get('foo'), b'None')
 
+    def test_set_float_value(self):
+        x = 1.23456789123456789
+        self.redis.set('foo', x)
+        self.assertEqual(float(self.redis.get('foo')), x)
+
     def test_saving_non_ascii_chars_as_value(self):
         self.assertEqual(self.redis.set('foo', 'Ñandu'), True)
         self.assertEqual(self.redis.get('foo'),
@@ -287,6 +292,11 @@ def test_incrbyfloat_bad_type(self):
         with self.assertRaisesRegexp(redis.ResponseError, 'not a valid float'):
             self.redis.incrbyfloat('foo', 1.0)
 
+    def test_incrbyfloat_precision(self):
+        x = 1.23456789123456789
+        self.assertEqual(self.redis.incrbyfloat('foo', x), x)
+        self.assertEqual(float(self.redis.get('foo')), x)
+
     def test_decr(self):
         self.redis.set('foo', 10)
         self.assertEqual(self.redis.decr('foo'), 9)
@@ -884,6 +894,11 @@ def test_hincrbyfloat_with_non_float_amount_raises_error(self):
         with self.assertRaises(redis.ResponseError):
             self.redis.hincrbyfloat('foo', 'counter', 'cat')
 
+    def test_hincrbyfloat_precision(self):
+        x = 1.23456789123456789
+        self.assertEqual(self.redis.hincrbyfloat('foo', 'bar', x), x)
+        self.assertEqual(float(self.redis.hget('foo', 'bar')), x)
+
     def test_hsetnx(self):
         self.assertEqual(self.redis.hsetnx('foo', 'newkey', 'v1'), True)
         self.assertEqual(self.redis.hsetnx('foo', 'newkey', 'v1'), False)