kunit_tool: added tests for throw_error_if_not_subset()

Added tests to make sure method correctly throws exception if the first
param is not a subset of the second param.

Signed-off-by: Maria Del Carmen Ignacio <mariaignacio@google.com>
Signed-off-by: Darya Verzhbinsky <daryaver@google.com>
Change-Id: I651d96fbb8e59be03eba82bb2330336018493f6e
1 file changed