The engine service test case is too big to maintain. This patch is a
first attempt to decompose it into smaller units. Several things to
note for this patch and those following this one:
1) all engine service tests are expected to be put into the 'engine'
subdir;
2) there will duplicated code in the new unit tests, but they are
expected to be moved to a shared module eventually;
3) there could be some modifications related to switching from mox to
mock, but that may not be included in every single patch.
Change-Id: I87c18935700e68985abbdf7550cdd843fce0c053
9b1a510b81