Added resultset limit and skip methods. issue #1

cormoran/resultset.py

@@ -23,6 +23,7 @@ def __init__(self, persistence, persistent_cls):
         self._persistent_cls = persistent_cls
 
         self._filters = {}
+        self._limit = slice(None)
 
     def __iter__(self):
         results = self._persistence.select(
@@ -42,3 +43,11 @@ def filter(self, **kwargs):
             self._filters[k] = kwargs[k]
 
         return self
+
+    def limit(self, stop):
+        self._limit = slice(self._limit.start, stop)
+        return self
+
+    def skip(self, start):
+        self._limit = slice(start, self._limit.stop or -1)
+        return self

tests/unit/test_resultset.py

@@ -71,6 +71,51 @@ def test_filter_returns_the_resultset_object(self):
 
         assert_that(resultset, is_(self.resultset))
 
+    def test_limit_adds_slice_with_stop_value(self):
+        self.resultset.limit(5)
+
+        limit = self.resultset._limit
+
+        assert_that(limit, instance_of(slice))
+        assert_that(limit.stop, is_(5))
+
+    def test_skip_adds_slice_with_start_value_and_stop_negative(self):
+        self.resultset.skip(2)
+
+        limit = self.resultset._limit
+
+        assert_that(limit, instance_of(slice))
+        assert_that(limit.start, is_(2))
+        assert_that(limit.stop, is_(-1))
+
+    def test_limit_with_already_set_skip_preserves_skip(self):
+        self.resultset.skip(1)
+        self.resultset.limit(2)
+
+        limit = self.resultset._limit
+
+        assert_that(limit.start, is_(1))
+        assert_that(limit.stop, is_(2))
+
+    def test_skip_with_already_set_limit_preserves_limit(self):
+        self.resultset.limit(1)
+        self.resultset.skip(2)
+
+        limit = self.resultset._limit
+
+        assert_that(limit.start, is_(2))
+        assert_that(limit.stop, is_(1))
+
+    def test_limit_returns_the_resultset_object(self):
+        resultset = self.resultset.limit(1)
+
+        assert_that(resultset, is_(self.resultset))
+
+    def test_skip_returns_the_resultset_object(self):
+        resultset = self.resultset.skip(1)
+
+        assert_that(resultset, is_(self.resultset))
+
     def result(self):
         return [
             {u'_id': 1, u'field': u'test1'},