T24c: Agent, changes

- FileChangeCard: a proposed change to one file, its path and counts,
  Reject and Accept in a slot that keeps presses off the header; opened,
  the diff through a headless git::DiffViewer with its folds opening
- MultiFileDiffReview: every file at once, the total counts, how many are
  reviewed, Reject all and Accept all; verdicts as collab::Decision
- git::DiffViewer gains headless, leaving the file's header to its owner
- CommandExecutionCard is terminal::CommandBlock
- gallery: three proposed files and a command's block

src/agent/tests/mod.rs

@@ -0,0 +1,158 @@
+use gpui::{
+    Context, Entity, IntoElement, KeyBinding, KeyUpEvent, Keystroke, ParentElement, Render, Styled,
+    TestAppContext, VisualTestContext, Window, div,
+};
+
+mod changes;
+
+use super::{AgentProgress, Permission, PermissionPrompt, ToolApprovalDialog};
+use crate::{forms, primitives::FocusNext, theme::Theme};
+
+/// An approval dialog while open, and the answers it gave.
+struct Asking {
+    open: bool,
+    answers: Vec<bool>,
+}
+
+impl Render for Asking {
+    fn render(&mut self, _: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
+        let view = cx.entity();
+        div().size_full().children(self.open.then(|| {
+            ToolApprovalDialog::new(
+                "approve",
+                "write_file",
+                r#"{ "path": "lift.rs" }"#,
+                move |approved, _, cx| {
+                    view.update(cx, |asking, cx| {
+                        asking.answers.push(approved);
+                        asking.open = false;
+                        cx.notify();
+                    })
+                },
+            )
+        }))
+    }
+}
+
+pub(super) fn settle(cx: &mut VisualTestContext) {
+    cx.run_until_parked();
+    cx.update(|window, _| window.refresh());
+    cx.run_until_parked();
+}
+
+/// Presses and releases `key`, a frame apart.
+pub(super) fn press(key: &str, cx: &mut VisualTestContext) {
+    cx.simulate_keystrokes(key);
+    settle(cx);
+    cx.simulate_event(KeyUpEvent {
+        keystroke: Keystroke::parse(key).expect("a key"),
+    });
+    settle(cx);
+}
+
+fn asking(cx: &mut TestAppContext) -> (Entity<Asking>, &mut VisualTestContext) {
+    cx.update(|cx| {
+        Theme::init(cx);
+        forms::bind_keys(cx);
+        cx.bind_keys([KeyBinding::new("tab", FocusNext, None)]);
+    });
+    let (view, cx) = cx.add_window_view(|_, _| Asking {
+        open: true,
+        answers: Vec::new(),
+    });
+    cx.update(|window, _| window.activate_window());
+    settle(cx);
+    (view, cx)
+}
+
+#[gpui::test]
+fn escape_denies_the_call(cx: &mut TestAppContext) {
+    let (view, cx) = asking(cx);
+    press("escape", cx);
+    assert_eq!(
+        view.read_with(cx, |asking, _| asking.answers.clone()),
+        [false]
+    );
+}
+
+#[gpui::test]
+fn run_approves_the_call_once(cx: &mut TestAppContext) {
+    let (view, cx) = asking(cx);
+    press("tab", cx);
+    press("tab", cx);
+    press("tab", cx);
+    press("enter", cx);
+    assert_eq!(
+        view.read_with(cx, |asking, _| asking.answers.clone()),
+        [true]
+    );
+}
+
+/// A permission prompt and the answers it gave.
+struct Prompting {
+    answers: Vec<Permission>,
+}
+
+impl Render for Prompting {
+    fn render(&mut self, _: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
+        let view = cx.entity();
+        div().w_full().child(
+            PermissionPrompt::new("permission", "Run commands here?", move |answer, _, cx| {
+                view.update(cx, |prompting, _| prompting.answers.push(answer))
+            })
+            .detail("cargo test"),
+        )
+    }
+}
+
+#[gpui::test]
+fn the_prompt_walks_deny_always_then_once(cx: &mut TestAppContext) {
+    cx.update(|cx| {
+        Theme::init(cx);
+        forms::bind_keys(cx);
+    });
+    let (view, cx) = cx.add_window_view(|_, _| Prompting {
+        answers: Vec::new(),
+    });
+    cx.update(|window, _| window.activate_window());
+    settle(cx);
+    for _ in 0..3 {
+        cx.update(|window, _| window.focus_next());
+    }
+    press("enter", cx);
+    assert_eq!(
+        view.read_with(cx, |prompting, _| prompting.answers.clone()),
+        [Permission::Once]
+    );
+}
+
+#[test]
+#[should_panic(expected = "progress of 6 in 5")]
+fn progress_past_its_total_fails_loud() {
+    let _ = AgentProgress::new("progress", "Writing", 6, 5);
+}
+
+/// A progress bar for a task of one step, `done` or not.
+struct Single {
+    done: usize,
+}
+
+impl Render for Single {
+    fn render(&mut self, _: &mut Window, _: &mut Context<Self>) -> impl IntoElement {
+        div()
+            .w_full()
+            .child(AgentProgress::new("single", "The one step", self.done, 1))
+    }
+}
+
+#[gpui::test]
+fn a_task_of_one_step_draws_before_and_after(cx: &mut TestAppContext) {
+    cx.update(Theme::init);
+    let (view, cx) = cx.add_window_view(|_, _| Single { done: 0 });
+    settle(cx);
+    view.update(cx, |single, cx| {
+        single.done = 1;
+        cx.notify();
+    });
+    settle(cx);
+}