TUI Testing

sipnab tests its TUI at three levels.

1. Snapshot tests (tests/tui_snapshot_test.rs)

Uses ratatui’s TestBackend to render views to an in-memory buffer, then insta for snapshot comparison.

Running

cargo test --features tui --test tui_snapshot_test

Updating snapshots

When rendering changes intentionally — --accept rewrites the .snap files in place, and staging them in the same commit is what keeps CI comparing against the new rendering:

# Run all of these, in order.
cargo insta test --features tui --accept
git add tests/snapshots/

Adding a new snapshot test

1. Create a test function that renders to TestBackend
2. Call insta::assert_snapshot!(buffer_to_string(&terminal))
3. Run cargo insta test --accept to create the initial snapshot
4. Commit the .snap file

2. State machine tests (tests/tui_state_test.rs)

Tests App state transitions without rendering. Uses App::new_test() and App::handle_key().

cargo test --features tui --test tui_state_test

3. PTY end-to-end tests (tests/tui_e2e_test.rs)

Drives the real binary inside a detached tmux session — not a bare PTY. sipnab’s TUI queries the terminal at startup (crossterm emits ESC[6n to read the cursor position), and a bare pseudo-terminal has no emulator behind it to answer, so the TUI aborts with cursor position could not be read. tmux is a terminal emulator: it answers the query, provides a real window size, and lets the test send keys and snapshot the screen with capture-pane. These are #[ignore] by default and need tmux on PATH.

cargo test --features tui --test tui_e2e_test -- --ignored

These tests are slower (~2s each) and may be flaky in CI.