Method reset

tests/fastled_core.cpp:975–984

    const IChannel* mLastChannel = nullptr;

    void reset() {
        mCreatedCount = 0;
        mBeginDestroyCount = 0;
        mAddedCount = 0;
        mRemovedCount = 0;
        mConfiguredCount = 0;
        mEnqueuedCount = 0;
        mLastEngineName.clear();
        mLastChannel = nullptr;
    }

    void onCreated(const IChannel& ch) {
        mCreatedCount++;