MockCharmStore.With{AuthAttrs,TestMode,DefaultSeries} are setters

[davecheney]

func (s *MockCharmStore) WithAuthAttrs(auth string) charm.Repository {
    s.AuthAttrs = auth
    return s
}

func (s *MockCharmStore) WithTestMode(testMode bool) charm.Repository {
    s.TestMode = testMode
    return s
}

func (s *MockCharmStore) WithDefaultSeries(series string) charm.Repository {
    s.DefaultSeries = series
    return s
}

The following methods appear to return a copy of their receiver with a particular testing setting specified. However they do not, they modify their receiver and return themselves, not a copy.

This is bad for several reasons, none the least it produces a race condition as there is no synchronisation for these actions.