rodio 0.22 tightened SamplesBuffer::new to require NonZero<u16> for channels and NonZero<u32> for sample_rate, but the visualizer test fixtures still passed bare integer literals — so the qbz-audio test binary stopped building. Wrap both call sites in NonZero::new(...) .unwrap() so cargo test -p qbz-audio compiles again. Pure test-only change; runtime visualizer code was already migrated. cc