Prepare v2.2.1 release.

Signed-off-by: crynobone <crynobone@gmail.com>
Add mockery and ApplicationClientTrait test case.

Signed-off-by: crynobone <crynobone@gmail.com>
Improve testcase coverage.

Signed-off-by: crynobone <crynobone@gmail.com>
Merge branch '2.2'