Add unit test for CarrierConfigLoader
Change CarrierConfigLoader a bit to make it more testable:
1. Inject SubscriptionInfoUpdater into CarrierConfigLoader to make
it both mockable and verifible.
2. Inject Looper into CarrirConfigLoader to take advantage of
TestableLooper in UT.
3. User PersistableBundle.EMPTY instead of creating new empty
instance to make it value comparable since the class does not
override equals method.
4. Make configs readable to test case to verify the values
(intead of verifying the behavior).
Bug: 182922049
Test: atest com.android.phone.CarrierConfigLoaderTest
Change-Id: Ia29f6daef606e13578311bfccd350cc1d891fca0
3 files changed