Add headless UI tests with kittest

src/app/tests.rs

@@ -0,0 +1,93 @@
+use super::*;
+use crate::model::{Node, NodeKind};
+use egui_kittest::{Harness, kittest::Queryable};
+
+#[test]
+fn the_welcome_canvas_is_valid_and_connected() {
+    let canvas = welcome_canvas();
+    assert_eq!(canvas.nodes.len(), 4);
+    assert_eq!(canvas.edges.len(), 3);
+    let mut copy = canvas.clone();
+    assert_eq!(copy.drop_dangling_edges(), 0);
+    // And it round-trips through the file format.
+    assert_eq!(Canvas::from_json(&canvas.to_json()).unwrap(), canvas);
+}
+
+// -- the whole application, driven the way a user drives it: real widgets,
+// found by the label on them and clicked, with no window, compositor or
+// pointer in the way.
+
+/// Whether a harness can draw. Only the tests that look at a frame ask
+/// for a renderer, so that the rest have nothing to say about the graphics
+/// stack of the machine they run on.
+enum Renderer {
+    None,
+    Wgpu,
+}
+
+/// The app on a canvas holding one note, with `text` in it.
+fn harness_with_a_note(text: &str, renderer: Renderer) -> Harness<'static, App> {
+    let mut canvas = Canvas::default();
+    canvas.nodes.push(Node::new(
+        "n",
+        NodeKind::Text {
+            text: text.to_owned(),
+        },
+        0,
+        0,
+        300,
+        200,
+    ));
+    let builder = Harness::builder().with_size(egui::vec2(1200.0, 900.0));
+    let builder = match renderer {
+        Renderer::None => builder,
+        Renderer::Wgpu => builder.wgpu(),
+    };
+    let mut harness = builder.build_eframe(|cc| App::new(cc, None));
+    harness.state_mut().doc = Document::new();
+    harness.state_mut().doc.canvas = canvas;
+    harness.run();
+    harness
+}
+
+/// The shell is real widgets too, found by the label on them.
+#[test]
+fn the_toolbar_adds_a_note_to_the_canvas() {
+    let mut harness = harness_with_a_note("the only one", Renderer::None);
+    assert_eq!(harness.state().doc.canvas.nodes.len(), 1);
+
+    harness.get_by_label("Note").click();
+    harness.run();
+
+    assert_eq!(harness.state().doc.canvas.nodes.len(), 2);
+}
+
+/// The editor window as it is drawn: the text filling it, the ways out
+/// along the bottom. Run `UPDATE_SNAPSHOTS=1 cargo test` after changing it
+/// on purpose, and look at `tests/snapshots/*.diff.png` when it fails.
+#[test]
+fn the_editor_window_is_drawn_as_it_should_be() {
+    let mut harness = harness_with_a_note("## A note\n\nWith text in it.", Renderer::Wgpu);
+    harness.state_mut().view.edit_node("n");
+    harness.run();
+    harness.snapshot("editor-window");
+}
+
+#[test]
+fn close_and_fit_sizes_the_card_and_closes_the_editor() {
+    // More text than a 300x200 card can show.
+    let mut harness = harness_with_a_note(&"word ".repeat(200), Renderer::None);
+    harness.state_mut().view.edit_node("n");
+    harness.run();
+
+    harness.get_by_label("Close & Fit").click();
+    harness.run();
+
+    let app = harness.state();
+    assert_eq!(app.view.editing(), None, "the editor stayed open");
+    assert!(
+        app.doc.canvas.node("n").unwrap().height > 200,
+        "the card was not grown to its text"
+    );
+    assert_eq!(app.doc.undo_label(), Some("Fit to text"));
+}