Add GetChannelMember method to plugin API (#7930)

plugin/plugintest/api.go

@@ -207,6 +207,16 @@ func (m *API) UpdateChannel(channel *model.Channel) (*model.Channel, *model.AppE
 	return channelOut, err
 }
 
+func (m *API) GetChannelMember(channelId, userId string) (*model.ChannelMember, *model.AppError) {
+	ret := m.Called(channelId, userId)
+	if f, ok := ret.Get(0).(func(_, _ string) (*model.ChannelMember, *model.AppError)); ok {
+		return f(channelId, userId)
+	}
+	member, _ := ret.Get(0).(*model.ChannelMember)
+	err, _ := ret.Get(1).(*model.AppError)
+	return member, err
+}
+
 func (m *API) CreatePost(post *model.Post) (*model.Post, *model.AppError) {
 	ret := m.Called(post)
 	if f, ok := ret.Get(0).(func(*model.Post) (*model.Post, *model.AppError)); ok {