T21a: Documents, editing

- markdown read with pulldown-cmark: marks for live styling, blocks, links, words
- forms::Highlight gains weight, slant and strike; measure and paint share runs
- Inter Italic embedded, so emphasis reads slanted
- forms::mention's popup and keys become Suggestions, shared with the editors
- RichTextEditor with FixedFormatToolbar, the floating toolbar, LinkEditor,
  @ and : suggestions, WordCount and ReadingTime
- MarkdownEditor: visual (a pressed block opens as source), source, split
- BlockEditor: prose, lists, to-dos, quotes, callouts, toggles, code, math,
  diagrams the app draws, dividers, tables that grow and merge, pictures to
  resize and align, cards for video and pages, columns, synced text; slash menu,
  markdown shortcuts, handles that drag and open a menu, one undo for all
- TodoItem and Checklist
- icons: heading-1..3, workflow, merge
- gallery: the Documents page with scripted states

src/documents/tests.rs

@@ -0,0 +1,184 @@
+use gpui::{AppContext as _, Entity, Focusable, TestAppContext, VisualTestContext};
+
+use super::{BlockData, BlockEditor, BlockKind};
+use crate::{forms, theme::Theme};
+
+fn open(
+    blocks: Vec<BlockData>,
+    cx: &mut TestAppContext,
+) -> (Entity<BlockEditor>, &mut VisualTestContext) {
+    cx.update(|cx| {
+        Theme::init(cx);
+        forms::bind_keys(cx);
+        super::bind_keys(cx);
+    });
+    let (editor, cx) = cx.add_window_view(|window, cx| BlockEditor::new(blocks, window, cx));
+    settle(cx);
+    (editor, cx)
+}
+
+fn settle(cx: &mut VisualTestContext) {
+    cx.run_until_parked();
+    cx.update(|window, _| window.refresh());
+    cx.run_until_parked();
+}
+
+fn blocks(
+    editor: &Entity<BlockEditor>,
+    cx: &mut VisualTestContext,
+) -> Vec<(BlockKind, Vec<String>)> {
+    cx.update(|_, cx| {
+        editor
+            .read(cx)
+            .blocks(cx)
+            .into_iter()
+            .map(|block| (block.kind, block.texts))
+            .collect()
+    })
+}
+
+/// Puts the caret in block `ix`'s first field at byte `at`.
+fn caret(editor: &Entity<BlockEditor>, ix: usize, at: usize, cx: &mut VisualTestContext) {
+    cx.update(|window, cx| {
+        let field = editor.read(cx).blocks[ix].fields[0].clone();
+        field.update(cx, |field, cx| field.select(at..at, cx));
+        window.focus(&field.focus_handle(cx));
+    });
+    settle(cx);
+}
+
+fn text(kind: BlockKind, text: &str) -> (BlockKind, Vec<String>) {
+    (kind, vec![text.to_string()])
+}
+
+#[gpui::test]
+fn enter_splits_prose_at_the_caret(cx: &mut TestAppContext) {
+    let (editor, cx) = open(vec![BlockData::new(BlockKind::Bullet, ["lift"])], cx);
+    caret(&editor, 0, 2, cx);
+    cx.simulate_keystrokes("enter");
+    settle(cx);
+    assert_eq!(
+        blocks(&editor, cx),
+        [text(BlockKind::Bullet, "li"), text(BlockKind::Bullet, "ft")]
+    );
+}
+
+#[gpui::test]
+fn backspace_at_the_start_joins_up_and_undo_parts_them(cx: &mut TestAppContext) {
+    let (editor, cx) = open(
+        vec![
+            BlockData::new(BlockKind::Paragraph, ["tone "]),
+            BlockData::new(BlockKind::Paragraph, ["lift"]),
+        ],
+        cx,
+    );
+    caret(&editor, 1, 0, cx);
+    cx.simulate_keystrokes("backspace");
+    settle(cx);
+    assert_eq!(
+        blocks(&editor, cx),
+        [text(BlockKind::Paragraph, "tone lift")]
+    );
+    cx.simulate_keystrokes("cmd-z");
+    settle(cx);
+    assert_eq!(
+        blocks(&editor, cx),
+        [
+            text(BlockKind::Paragraph, "tone "),
+            text(BlockKind::Paragraph, "lift")
+        ],
+        "undo brings the joined block back"
+    );
+}
+
+#[gpui::test]
+fn markdown_typed_at_a_paragraphs_start_changes_its_kind(cx: &mut TestAppContext) {
+    let (editor, cx) = open(vec![BlockData::new(BlockKind::Paragraph, [""])], cx);
+    caret(&editor, 0, 0, cx);
+    cx.simulate_input("## Lift");
+    settle(cx);
+    assert_eq!(blocks(&editor, cx), [text(BlockKind::Heading(2), "Lift")]);
+}
+
+#[gpui::test]
+fn backspace_turns_a_heading_back_into_text(cx: &mut TestAppContext) {
+    let (editor, cx) = open(vec![BlockData::new(BlockKind::Heading(1), ["Lift"])], cx);
+    caret(&editor, 0, 0, cx);
+    cx.simulate_keystrokes("backspace");
+    settle(cx);
+    assert_eq!(blocks(&editor, cx), [text(BlockKind::Paragraph, "Lift")]);
+}
+
+#[gpui::test]
+fn a_press_in_a_blocks_text_puts_the_caret_there(cx: &mut TestAppContext) {
+    let (editor, cx) = open(vec![BlockData::new(BlockKind::Paragraph, ["lift"])], cx);
+    cx.simulate_click(
+        gpui::point(gpui::px(300.0), gpui::px(10.0)),
+        gpui::Modifiers::none(),
+    );
+    settle(cx);
+    let focused = cx.update(|window, cx| editor.read(cx).focused(window, cx));
+    assert!(focused.is_some(), "the press focuses the block's field");
+    cx.simulate_keystrokes("enter");
+    settle(cx);
+    assert_eq!(blocks(&editor, cx).len(), 2);
+}
+
+/// The editor at a fixed width inside a row, as a page holds it.
+struct Hosted(Entity<BlockEditor>);
+
+impl gpui::Render for Hosted {
+    fn render(
+        &mut self,
+        _: &mut gpui::Window,
+        _: &mut gpui::Context<Self>,
+    ) -> impl gpui::IntoElement {
+        use gpui::{ParentElement, Styled};
+        gpui::div()
+            .flex()
+            .child(gpui::div().w(gpui::px(760.0)).child(self.0.clone()))
+    }
+}
+
+#[gpui::test]
+fn a_press_past_the_words_still_lands_in_the_block(cx: &mut TestAppContext) {
+    cx.update(|cx| {
+        Theme::init(cx);
+        forms::bind_keys(cx);
+        super::bind_keys(cx);
+    });
+    let (host, cx) = cx.add_window_view(|window, cx| {
+        let editor = cx.new(|cx| {
+            BlockEditor::new(
+                vec![BlockData::new(BlockKind::Paragraph, ["lift"])],
+                window,
+                cx,
+            )
+        });
+        Hosted(editor)
+    });
+    settle(cx);
+    cx.simulate_click(
+        gpui::point(gpui::px(700.0), gpui::px(10.0)),
+        gpui::Modifiers::none(),
+    );
+    settle(cx);
+    let editor = cx.update(|_, cx| host.read(cx).0.clone());
+    let focused = cx.update(|window, cx| editor.read(cx).focused(window, cx));
+    assert!(focused.is_some(), "the press focuses the block's field");
+}
+
+#[gpui::test]
+fn a_press_beside_a_blocks_text_puts_the_caret_at_its_end(cx: &mut TestAppContext) {
+    let (editor, cx) = open(vec![BlockData::new(BlockKind::Paragraph, ["lift"])], cx);
+    cx.simulate_click(
+        gpui::point(gpui::px(300.0), gpui::px(1.0)),
+        gpui::Modifiers::none(),
+    );
+    settle(cx);
+    let focused = cx.update(|window, cx| editor.read(cx).focused(window, cx));
+    assert_eq!(
+        focused,
+        Some((editor.read_with(cx, |editor, _| editor.blocks[0].key), 0))
+    );
+}