feat: add local and remote repository diff views

tests/diff.rs

@@ -0,0 +1,154 @@
+use std::{
+    fs,
+    path::{Path, PathBuf},
+    process::Command,
+    sync::atomic::{AtomicU64, Ordering},
+    thread,
+    time::{Duration, Instant},
+};
+
+use vamp::{diff::Phase, editor::Input, session::EditorSession};
+
+static NEXT: AtomicU64 = AtomicU64::new(0);
+
+struct Fixture(PathBuf);
+
+impl Fixture {
+    fn new() -> Self {
+        let root = std::env::temp_dir().join(format!(
+            "vamp-diff-session-{}-{}",
+            std::process::id(),
+            NEXT.fetch_add(1, Ordering::Relaxed),
+        ));
+        fs::create_dir_all(root.join("repo")).unwrap();
+        Self(root)
+    }
+
+    fn git(&self, args: &[&str]) -> String {
+        let output = Command::new("git")
+            .args(args)
+            .current_dir(self.0.join("repo"))
+            .env("GIT_CONFIG_NOSYSTEM", "1")
+            .env("GIT_CONFIG_GLOBAL", "/dev/null")
+            .env("GIT_AUTHOR_NAME", "Diff Fixture")
+            .env("GIT_AUTHOR_EMAIL", "fixture@example.invalid")
+            .env("GIT_COMMITTER_NAME", "Diff Fixture")
+            .env("GIT_COMMITTER_EMAIL", "fixture@example.invalid")
+            .env("GIT_AUTHOR_DATE", "2000-01-01T00:00:00Z")
+            .env("GIT_COMMITTER_DATE", "2000-01-01T00:00:00Z")
+            .output()
+            .unwrap();
+        assert!(
+            output.status.success(),
+            "{}",
+            String::from_utf8_lossy(&output.stderr)
+        );
+        String::from_utf8(output.stdout).unwrap().trim().to_owned()
+    }
+}
+
+impl Drop for Fixture {
+    fn drop(&mut self) {
+        let _ = fs::remove_dir_all(&self.0);
+    }
+}
+
+fn wait_until(session: &mut EditorSession, ready: impl Fn(&EditorSession) -> bool) {
+    let deadline = Instant::now() + Duration::from_secs(10);
+    while !ready(session) {
+        session.poll();
+        assert!(
+            Instant::now() < deadline,
+            "diff state: {:?}",
+            session.editor().diff()
+        );
+        if let Some(diff) = session.editor().diff() {
+            assert!(diff.error.is_none(), "{:?}", diff.error);
+        }
+        thread::sleep(Duration::from_millis(1));
+    }
+}
+
+fn type_query(session: &mut EditorSession, text: &str) {
+    for ch in text.chars() {
+        session.handle(Input::Char(ch));
+    }
+}
+
+#[test]
+fn typed_diff_compares_disk_not_unsaved_buffers_and_preserves_undo() {
+    let fixture = Fixture::new();
+    fixture.git(&["init", "-q"]);
+    let source = fixture.0.join("repo/buffer.rs");
+    fs::write(&source, "before\n").unwrap();
+    fixture.git(&["add", "buffer.rs"]);
+    fixture.git(&["commit", "-qm", "base"]);
+    let base = fixture.git(&["rev-parse", "HEAD"]);
+    fs::write(&source, "after\n").unwrap();
+    let config = fixture.0.join("config.rb");
+    fs::write(
+        &config,
+        "Vamp.configure do |config|\n config.clipboard_mode = 'separate'\n config.bind 'leader d', config.core.diff\nend\n",
+    )
+    .unwrap();
+    let mut session =
+        EditorSession::open(Some(source.clone()), vec!["text".into()], Some(&config)).unwrap();
+    assert!(session.editor().startup_diagnostic().is_none());
+    for input in [Input::Char('i'), Input::Char('u'), Input::Escape] {
+        session.handle(input);
+    }
+    let cursor = session.editor().cursor();
+    session.handle(Input::Char(' '));
+    session.handle(Input::Char('d'));
+    wait_until(&mut session, |session| {
+        session
+            .editor()
+            .diff()
+            .is_some_and(|diff| diff.catalog.is_some() && !diff.loading)
+    });
+    type_query(&mut session, &base);
+    session.handle(Input::Down);
+    session.handle(Input::Enter);
+    assert_eq!(session.editor().diff().unwrap().phase, Phase::After);
+    session.handle(Input::Enter);
+    wait_until(&mut session, |session| {
+        session
+            .editor()
+            .diff()
+            .is_some_and(|diff| diff.phase == Phase::View)
+    });
+    let comparison = session
+        .editor()
+        .diff()
+        .unwrap()
+        .comparison
+        .as_ref()
+        .unwrap();
+    assert_eq!(comparison.files.len(), 1);
+    let file = &comparison.files[0];
+    assert_eq!(file.path, Path::new("buffer.rs"));
+    assert_eq!(file.before, ["before"]);
+    assert_eq!(file.after, ["after"]);
+    for input in [
+        Input::Char('i'),
+        Input::Char('x'),
+        Input::Paste("overwrite".into()),
+    ] {
+        session.handle(input);
+    }
+    session.handle(Input::Escape);
+    assert!(session.editor().diff().is_none());
+    assert_eq!(session.editor().context().text, "uafter\n");
+    assert!(session.editor().dirty());
+    assert_eq!(session.editor().cursor(), cursor);
+    assert_eq!(fs::read_to_string(&source).unwrap(), "after\n");
+    session.handle(Input::Char('u'));
+    assert_eq!(session.editor().context().text, "after\n");
+    session.execute(":diff");
+    assert!(session.editor().diff().is_some());
+    session.handle(Input::Escape);
+    session.poll();
+    assert!(session.editor().diff().is_none());
+    assert_eq!(fixture.git(&["rev-parse", "HEAD"]), base);
+    assert_eq!(fixture.git(&["status", "--porcelain"]), "M buffer.rs");
+}