Support a dry run of payload generation.

If a dryrun is specified, the generated payload is neither signed nor
uploaded.

BUG=chromium:1065500
TEST=./run_tests

Change-Id: Ie1ce1489984831e420db3dd842163d7284e5075b
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2149956
Reviewed-by: Sean Abraham <seanabraham@chromium.org>
Reviewed-by: George Engelbrecht <engeg@google.com>
Commit-Queue: Navil Perez <navil@google.com>
Tested-by: Navil Perez <navil@google.com>
diff --git a/api/controller/payload_unittest.py b/api/controller/payload_unittest.py
index a0086aa..daf2b7e 100644
--- a/api/controller/payload_unittest.py
+++ b/api/controller/payload_unittest.py
@@ -42,8 +42,12 @@
         build=tgt_build, image_type=6, milestone='R70')
 
     self.req = payload_pb2.PayloadGenerationRequest(
-        tgt_unsigned_image=tgt_image, src_unsigned_image=src_image,
-        bucket='test-destination-bucket', verify=True, keyset='update_signer')
+        tgt_unsigned_image=tgt_image,
+        src_unsigned_image=src_image,
+        bucket='test-destination-bucket',
+        verify=True,
+        keyset='update_signer',
+        dryrun=False)
 
     self.result = payload_pb2.PayloadGenerationResult()