add basic mustbe_deferred tests

scrapy/tests/test_utils_defer.py

@@ -0,0 +1,33 @@
+from itertools import imap
+from twisted.trial import unittest
+
+from twisted.internet import reactor
+from twisted.internet.defer import Deferred
+from scrapy.utils.defer import mustbe_deferred
+
+
+class MustbeDeferredTest(unittest.TestCase):
+    def test_success_function(self):
+        steps = []
+        def _append(v):
+            steps.append(v)
+            return steps
+
+        dfd = mustbe_deferred(_append, 1)
+        dfd.addCallback(self.assertEqual, [1,2]) # it is [1] with maybeDeferred
+        steps.append(2) # add another value, that should be catched by assertEqual
+        return dfd
+
+    def test_unfired_deferred(self):
+        steps = []
+        def _append(v):
+            steps.append(v)
+            dfd = Deferred()
+            reactor.callLater(0, dfd.callback, steps)
+            return dfd
+
+        dfd = mustbe_deferred(_append, 1)
+        dfd.addCallback(self.assertEqual, [1,2]) # it is [1] with maybeDeferred
+        steps.append(2) # add another value, that should be catched by assertEqual
+        return dfd
+