(work in progress)
- Inject CommandService like other classes instead of passing it as method parameter
- Not solved: cyclic dependency CommandInitializer > ExecutableCommand > CommandService > CommandInitializer...
- Remove redundant uses of WrapperMock
- Use assertThat() from JUnit, not hamcrest
- Use hamcrest Matchers everywhere (not BaseMatchers etc.)
- Favor Mockito's argThat() over using ArgumentCaptor (more succinct)
- Delete useless test classes
