nebraska: behaviour-based "noupdate" unit test

Instead of testing the internal implementation of how Nebraska handles
update requests when the is no update available, we test the behaviour:
- create an update request of a valid app that does not have an update
- ensure that the response contains <updatecheck status="noupdate"/>

Also use GIVEN/WHEN/THEN format to document the test.

BUG=chromium:920404
TEST=./run_unittests

Change-Id: I63274254cab866e38b5dfb5e7b805aba3be6aa73
Reviewed-on: https://chromium-review.googlesource.com/1650716
Tested-by: Nicolas Norvez <[email protected]>
Commit-Ready: Nicolas Norvez <[email protected]>
Legacy-Commit-Queue: Commit Bot <[email protected]>
Reviewed-by: Jae Hoon Kim <[email protected]>
Reviewed-by: Xiaochu Liu <[email protected]>
Reviewed-by: Amin Hassani <[email protected]>
1 file changed