test for empty case & cleanup

Author: radix

effect/fold.py

@@ -25,6 +25,5 @@ def folder(acc, element):
 
 
 def sequence(effects):
-    def folder(acc, element):
-        return acc + [element]
-    return fold_effect(folder, [], effects)
+    """Perform each Effect serially, collecting their results into a list."""
+    return fold_effect(lambda acc, el: acc + [el], [], effects)

effect/test_fold.py

@@ -6,6 +6,9 @@
 from effect.testing import SequenceDispatcher
 
 
+def _disp(dispatcher):
+    return ComposedDispatcher([dispatcher, base_dispatcher])
+
 def test_fold_effect():
     """Behaves like foldM."""
     effs = [Effect('a'), Effect('b'), Effect('c')]
@@ -18,9 +21,7 @@ def test_fold_effect():
     eff = fold_effect(operator.add, 'Nil', effs)
 
     with dispatcher.consume():
-        result = sync_perform(
-            ComposedDispatcher([dispatcher, base_dispatcher]),
-            eff)
+        result = sync_perform(_disp(dispatcher), eff)
     assert result == 'NilEiBeeCee'
 
 
@@ -34,6 +35,7 @@ def test_fold_effect_empty():
 
 
 def test_sequence():
+    """Collects each Effectful result into a list."""
     effs = [Effect('a'), Effect('b'), Effect('c')]
     dispatcher = SequenceDispatcher([
         ('a', lambda i: 'Ei'),
@@ -44,5 +46,10 @@ def test_sequence():
 
     print "what the heck is sequence returning?", eff
     with dispatcher.consume():
-        result = sync_perform(dispatcher, eff)
+        result = sync_perform(_disp(dispatcher), eff)
     assert result == ['Ei', 'Bee', 'Cee']
+
+
+def test_sequence_empty():
+    """Returns an empty list when there are no Effects."""
+    assert sync_perform(base_dispatcher, sequence([])) == []