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STELLARR

Preset Switching

Test whenever you touch preset loading, restoreSession, clearGraph, plugin lifecycle, or StellarrProcessor graph management.

This is historically the most crash-prone area. The engine suspends the audio graph, tears down all blocks, creates new plugin instances, rebuilds connections, and resumes — all on the message thread while the audio thread is running.

Prerequisites

  • 2+ presets saved in a preset directory, each with different plugin chains
  • At least one “heavy” preset with 3+ plugins
  • Audio playing through the app (e.g. guitar input or test tone)

Test Cases

TC-PS-001: Switch between heavy presets

Steps:

  1. Load a preset with 3+ plugins in the chain
  2. Verify audio is flowing (output meter shows signal)
  3. Switch to a different heavy preset via the preset dropdown

Expected: No crash. Audio gap is brief (a click or short silence, not seconds). All plugins in the new preset produce audio.

TC-PS-002: Rapid preset switching

Steps:

  1. Load any preset
  2. Click through 3+ different presets in quick succession (as fast as you can click)

Expected: No crash, no hang. The final preset loads correctly and produces audio.

TC-PS-003: Switch with plugin editor open

Steps:

  1. Load a preset with at least one plugin
  2. Open the plugin’s editor window (gear icon in Options panel)
  3. Switch to a different preset

Expected: Plugin editor window closes. New preset loads without crash.

TC-PS-004: Switch with test tone playing

Steps:

  1. Enable the test tone on the Input block
  2. Switch to a different preset

Expected: Test tone stops (new preset has its own Input block). New preset loads cleanly.

TC-PS-005: New session clears graph

Steps:

  1. Load a heavy preset
  2. Choose New Preset from the save menu

Expected: All plugin blocks are removed. Graph shows only Input and Output blocks. No crash.

TC-PS-006: Save and reload preserves state

Steps:

  1. Load a preset with plugins
  2. Adjust a plugin’s parameters (open its editor, change a knob)
  3. Save the preset (Cmd+S)
  4. Switch to a different preset
  5. Switch back to the original preset

Expected: The plugin parameter changes from step 2 are preserved.

TC-PS-007: MIDI-triggered preset change

Steps:

  1. Assign Program Change to presets (Link icon on preset dropdown)
  2. Send a PC message from your MIDI controller

Expected: Preset switches to the corresponding index. No crash.

Notes: Requires a MIDI controller or software MIDI source.