insta-fun

SVG & WAV snapshot testing for FunDSP audio units.

Generate visual snapshots of audio processing units to catch regressions and verify signal behavior.

Note: Snapshot assertion uses insta::assert_binary_snapshot which is currently marked experimental.

Usage

use insta_fun::prelude::*;
use fundsp::prelude::*;

#[test]
fn example_test() {
    // Simple SVG snapshot (default output_mode = SvgChart)
    let unit = sine_hz::<f32>(440.0);
    let svg_bytes = snapshot_audio_unit(unit);

    // With input signal (impulse)
    let filter = lowpass_hz(1000.0, 1.0);
    let svg_bytes_with_input = snapshot_audio_unit_with_input(filter, InputSource::impulse());

    // Custom chart configuration (SvgChartConfig separated from SnapshotConfig)
    let chart = SvgChartConfigBuilder::default()
        .chart_title("Custom Sine")
        .show_grid(true)
        .build()
        .unwrap();
    let config = SnapshotConfigBuilder::default()
        .num_samples(2048)
        .output_mode(chart) // inject chart config
        .build()
        .unwrap();
    let custom_svg = snapshot_audio_unit_with_options(sine_hz::<f32>(440.0), config);

    // WAV output (audible snapshot)
    let wav_config = SnapshotConfigBuilder::default()
        .num_samples(2048)
        .output_mode(WavOutput::Wav16) // or WavOutput::Wav32
        .build()
        .unwrap();
    let wav_bytes = snapshot_audio_unit_with_input_and_options(sine_hz::<f32>(440.0), InputSource::None, wav_config);

    // Macro (produces both an SVG and a 16-bit WAV by default)
    assert_audio_unit_snapshot!(sine_hz::<f32>(440.0));

    // Macro with custom config (single output based on config.output_mode)
    let wav_only_cfg = SnapshotConfigBuilder::default()
        .output_mode(WavOutput::Wav32)
        .build()
        .unwrap();
    assert_audio_unit_snapshot!(sine_hz::<f32>(220.0), wav_only_cfg);
}

Features

• Visualizes audio unit inputs and outputs as SVG waveforms
• Generates audible WAV snapshots (16-bit & 32-bit)
• Supports multi-channel audio with color-coded traces
• Configurable sample count, processing mode, warmup, and abnormal sample handling
• Separate chart configuration via SvgChartConfigBuilder
• Built-in input generators (impulse, sine, custom, generator fn, unit passthrough)
• Tick or batch processing (up to fundsp::MAX_BUFFER_SIZE)
• Multiple chart layouts & label formatting options
• Assertion macro (default: both SVG + WAV16 when no custom config)

Optional feature: dot (Graphviz Net snapshots)

Generate Graphviz DOT snapshots of fundsp::net::Net wiring for debugging and documentation.

• What it does:

  • Builds a directed graph of units, global inputs/outputs, and port-labeled edges.
  • Emits DOT with preserved whitespace in labels for better readability.
  • Uses deterministic node/edge ordering for stable snapshots.

• Enable the feature:

  [dependencies]
  insta-fun = { version = "2", features = ["dot"] }

• Usage:

  use fundsp::prelude::*;
  use insta_fun::prelude::*;
  
  #[test]
  fn net_graph() {
      // 2 inputs, 2 outputs
      let mut net = Net::new(2, 2);
  
      // Build a small explicit graph
      let lp = net.push(Box::new(lowpass_hz(500.0, 0.7)));
      net.connect_input(0, lp, 0);
  
      let hp = net.push(Box::new(highpass_hz(1200.0, 0.6)));
      net.connect_input(1, hp, 0);
  
      let stereo = net.push(Box::new(multipass::<U2>()));
      net.connect(lp, 0, stereo, 0);
      net.connect(hp, 0, stereo, 1);
      net.pipe_output(stereo);
  
      // Produces my_net.dot snapshot via insta
      assert_dsp_net_snapshot!("my_net", net);
  }

• Notes:

  • The DOT functionality is gated behind the dot feature and pulls in petgraph only when enabled.
  • With dot disabled, the graph::snapshot_dsp_net_wiring function returns a tiny placeholder and tests using DOT are skipped.

Configuration Overview

SnapshotConfig controls audio generation parameters (sample_rate, num_samples, processing_mode, warm_up, allow_abnormal_samples, output_mode).

SvgChartConfig controls purely visual/chart properties (layout, titles, labels, colors, dimensions, etc) and is injected through SnapshotConfigBuilder::output_mode(chart_cfg).

Set WAV output by providing output_mode(WavOutput::Wav16) or output_mode(WavOutput::Wav32).

Macro arms without an explicit SnapshotConfig produce both an SVG chart (default SvgChartConfig) and a 16-bit WAV file. Arms with a provided SnapshotConfig produce exactly one snapshot determined by output_mode.

Processing Modes

• Tick: Process one sample at a time (default) targeting AudioUnit::tick
• Batch: Process chunks (<= 64) targeting AudioUnit::process

Examples

See snapshots for full list of example charts.

See tests for all usage examples.

Bonus

Snapshots of all the fundsp AudioNodes anvlkv.github.io/insta-fun

• Ready-made example suites (charts: 2000 samples; audio: 1 second each):
  • Oscillators: cargo run --example oscillators
  • Filters (impulse responses): cargo run --example filters
  • Time FX, dynamics, and noise: cargo run --example time_fx_and_noise
  • Advanced Oscillators (DSF, pulse & PWM): cargo run --example oscillators_advanced
  • Advanced Filters (nonlinear & morph progression): cargo run --example filters_advanced

The Unlicense

See LICENSE file for details.

P.S.

🩻🎇🏙️🌁

Happy testing!