Allow to toggle git hunk diffs (#11080)

Part of #4523

Added two new actions with the default keybindings

```
"cmd-'": "editor::ToggleHunkDiff",
"cmd-\"": "editor::ExpandAllHunkDiffs",
```

that allow to browse git hunk diffs in Zed:


https://github.com/zed-industries/zed/assets/2690773/9a8a7d10-ed06-4960-b4ee-fe28fc5c4768


The hunks are dynamic and alter on user folds and modifications, or
toggle hidden, if the modifications were not adjacent to the expanded
hunk.


Release Notes:

- Added `editor::ToggleHunkDiff` (`cmd-'`) and
`editor::ExpandAllHunkDiffs` (`cmd-"`) actions to browse git hunk diffs
in Zed

assets/keymaps/default-linux.json

@@ -138,6 +138,8 @@
       "ctrl-alt-space": "editor::ShowCharacterPalette",
       "ctrl-;": "editor::ToggleLineNumbers",
       "ctrl-k ctrl-r": "editor::RevertSelectedHunks",
+      "ctrl-'": "editor::ToggleHunkDiff",
+      "ctrl-\"": "editor::ExpandAllHunkDiffs",
       "ctrl-alt-g b": "editor::ToggleGitBlame"
     }
   },

assets/keymaps/default-macos.json

@@ -159,6 +159,8 @@
       "ctrl-cmd-space": "editor::ShowCharacterPalette",
       "cmd-;": "editor::ToggleLineNumbers",
       "cmd-alt-z": "editor::RevertSelectedHunks",
+      "cmd-'": "editor::ToggleHunkDiff",
+      "cmd-\"": "editor::ExpandAllHunkDiffs",
       "cmd-alt-g b": "editor::ToggleGitBlame"
     }
   },

assets/settings/default.json

@@ -299,7 +299,9 @@
   // The list of language servers to use (or disable) for all languages.
   //
   // This is typically customized on a per-language basis.
-  "language_servers": ["..."],
+  "language_servers": [
+    "..."
+  ],
   // When to automatically save edited buffers. This setting can
   // take four values.
   //
@@ -428,7 +430,9 @@
   "copilot": {
     // The set of glob patterns for which copilot should be disabled
     // in any matching file.
-    "disabled_globs": [".env"]
+    "disabled_globs": [
+      ".env"
+    ]
   },
   // Settings specific to journaling
   "journal": {
@@ -539,7 +543,12 @@
         // Default directories to search for virtual environments, relative
         // to the current working directory. We recommend overriding this
         // in your project's settings, rather than globally.
-        "directories": [".env", "env", ".venv", "venv"],
+        "directories": [
+          ".env",
+          "env",
+          ".venv",
+          "venv"
+        ],
         // Can also be 'csh', 'fish', and `nushell`
         "activate_script": "default"
       }

crates/collab/src/tests/editor_tests.rs

@@ -9,10 +9,15 @@ use editor::{
         ConfirmCodeAction, ConfirmCompletion, ConfirmRename, Redo, Rename, RevertSelectedHunks,
         ToggleCodeActions, Undo,
     },
-    test::editor_test_context::{AssertionContextManager, EditorTestContext},
+    test::{
+        editor_hunks,
+        editor_test_context::{AssertionContextManager, EditorTestContext},
+        expanded_hunks, expanded_hunks_background_highlights,
+    },
     Editor,
 };
 use futures::StreamExt;
+use git::diff::DiffHunkStatus;
 use gpui::{BorrowAppContext, TestAppContext, VisualContext, VisualTestContext};
 use indoc::indoc;
 use language::{
@@ -1875,7 +1880,7 @@ async fn test_inlay_hint_refresh_is_forwarded(
 }
 
 #[gpui::test]
-async fn test_multiple_types_reverts(cx_a: &mut TestAppContext, cx_b: &mut TestAppContext) {
+async fn test_multiple_hunk_types_revert(cx_a: &mut TestAppContext, cx_b: &mut TestAppContext) {
     let mut server = TestServer::start(cx_a.executor()).await;
     let client_a = server.create_client(cx_a, "user_a").await;
     let client_b = server.create_client(cx_b, "user_b").await;
@@ -1997,8 +2002,8 @@ struct Row10;"#};
     cx_a.executor().run_until_parked();
     cx_b.executor().run_until_parked();
 
-    // client, selects a range in the updated buffer, and reverts it
-    // both host and the client observe the reverted state (with one hunk left, not covered by client's selection)
+    // the client selects a range in the updated buffer, expands it to see the diff for each hunk in the selection
+    // the host does not see the diffs toggled
     editor_cx_b.set_selections_state(indoc! {r#"«ˇstruct Row;
         struct Row0.1;
         struct Row0.2;
@@ -2010,11 +2015,106 @@ struct Row10;"#};
 
         struct R»ow9;
         struct Row1220;"#});
+    editor_cx_b
+        .update_editor(|editor, cx| editor.toggle_hunk_diff(&editor::actions::ToggleHunkDiff, cx));
+    cx_a.executor().run_until_parked();
+    cx_b.executor().run_until_parked();
+    editor_cx_a.update_editor(|editor, cx| {
+        let snapshot = editor.snapshot(cx);
+        let all_hunks = editor_hunks(editor, &snapshot, cx);
+        let all_expanded_hunks = expanded_hunks(&editor, &snapshot, cx);
+        assert_eq!(
+            expanded_hunks_background_highlights(editor, &snapshot),
+            Vec::new(),
+        );
+        assert_eq!(
+            all_hunks,
+            vec![
+                ("".to_string(), DiffHunkStatus::Added, 1..3),
+                ("struct Row2;\n".to_string(), DiffHunkStatus::Removed, 4..4),
+                ("struct Row5;\n".to_string(), DiffHunkStatus::Modified, 6..7),
+                ("struct Row8;\n".to_string(), DiffHunkStatus::Removed, 9..9),
+                (
+                    "struct Row10;".to_string(),
+                    DiffHunkStatus::Modified,
+                    10..10,
+                ),
+            ]
+        );
+        assert_eq!(all_expanded_hunks, Vec::new());
+    });
+    editor_cx_b.update_editor(|editor, cx| {
+        let snapshot = editor.snapshot(cx);
+        let all_hunks = editor_hunks(editor, &snapshot, cx);
+        let all_expanded_hunks = expanded_hunks(&editor, &snapshot, cx);
+        assert_eq!(
+            expanded_hunks_background_highlights(editor, &snapshot),
+            vec![1..3, 8..9],
+        );
+        assert_eq!(
+            all_hunks,
+            vec![
+                ("".to_string(), DiffHunkStatus::Added, 1..3),
+                ("struct Row2;\n".to_string(), DiffHunkStatus::Removed, 5..5),
+                ("struct Row5;\n".to_string(), DiffHunkStatus::Modified, 8..9),
+                (
+                    "struct Row8;\n".to_string(),
+                    DiffHunkStatus::Removed,
+                    12..12
+                ),
+                (
+                    "struct Row10;".to_string(),
+                    DiffHunkStatus::Modified,
+                    13..13,
+                ),
+            ]
+        );
+        assert_eq!(all_expanded_hunks, &all_hunks[..all_hunks.len() - 1]);
+    });
+
+    // the client reverts the hunks, removing the expanded diffs too
+    // both host and the client observe the reverted state (with one hunk left, not covered by client's selection)
     editor_cx_b.update_editor(|editor, cx| {
         editor.revert_selected_hunks(&RevertSelectedHunks, cx);
     });
     cx_a.executor().run_until_parked();
     cx_b.executor().run_until_parked();
+    editor_cx_a.update_editor(|editor, cx| {
+        let snapshot = editor.snapshot(cx);
+        let all_hunks = editor_hunks(editor, &snapshot, cx);
+        let all_expanded_hunks = expanded_hunks(&editor, &snapshot, cx);
+        assert_eq!(
+            expanded_hunks_background_highlights(editor, &snapshot),
+            Vec::new(),
+        );
+        assert_eq!(
+            all_hunks,
+            vec![(
+                "struct Row10;".to_string(),
+                DiffHunkStatus::Modified,
+                10..10,
+            )]
+        );
+        assert_eq!(all_expanded_hunks, Vec::new());
+    });
+    editor_cx_b.update_editor(|editor, cx| {
+        let snapshot = editor.snapshot(cx);
+        let all_hunks = editor_hunks(editor, &snapshot, cx);
+        let all_expanded_hunks = expanded_hunks(&editor, &snapshot, cx);
+        assert_eq!(
+            expanded_hunks_background_highlights(editor, &snapshot),
+            Vec::new(),
+        );
+        assert_eq!(
+            all_hunks,
+            vec![(
+                "struct Row10;".to_string(),
+                DiffHunkStatus::Modified,
+                10..10,
+            )]
+        );
+        assert_eq!(all_expanded_hunks, Vec::new());
+    });
     editor_cx_a.assert_editor_state(indoc! {r#"struct Row;
         struct Row1;
         struct Row2;

crates/editor/src/actions.rs

@@ -253,6 +253,8 @@ gpui::actions!(
         TabPrev,
         ToggleGitBlame,
         ToggleGitBlameInline,
+        ToggleHunkDiff,
+        ExpandAllHunkDiffs,
         ToggleInlayHints,
         ToggleLineNumbers,
         ToggleSoftWrap,

crates/editor/src/display_map/block_map.rs

@@ -364,28 +364,33 @@ impl BlockMap {
                         (position.row(), TransformBlock::Custom(block.clone()))
                     }),
             );
-            blocks_in_edit.extend(
-                buffer
-                    .excerpt_boundaries_in_range((start_bound, end_bound))
-                    .map(|excerpt_boundary| {
-                        (
-                            wrap_snapshot
-                                .make_wrap_point(Point::new(excerpt_boundary.row, 0), Bias::Left)
-                                .row(),
-                            TransformBlock::ExcerptHeader {
-                                id: excerpt_boundary.id,
-                                buffer: excerpt_boundary.buffer,
-                                range: excerpt_boundary.range,
-                                height: if excerpt_boundary.starts_new_buffer {
-                                    self.buffer_header_height
-                                } else {
-                                    self.excerpt_header_height
+            if buffer.show_headers() {
+                blocks_in_edit.extend(
+                    buffer
+                        .excerpt_boundaries_in_range((start_bound, end_bound))
+                        .map(|excerpt_boundary| {
+                            (
+                                wrap_snapshot
+                                    .make_wrap_point(
+                                        Point::new(excerpt_boundary.row, 0),
+                                        Bias::Left,
+                                    )
+                                    .row(),
+                                TransformBlock::ExcerptHeader {
+                                    id: excerpt_boundary.id,
+                                    buffer: excerpt_boundary.buffer,
+                                    range: excerpt_boundary.range,
+                                    height: if excerpt_boundary.starts_new_buffer {
+                                        self.buffer_header_height
+                                    } else {
+                                        self.excerpt_header_height
+                                    },
+                                    starts_new_buffer: excerpt_boundary.starts_new_buffer,
                                 },
-                                starts_new_buffer: excerpt_boundary.starts_new_buffer,
-                            },
-                        )
-                    }),
-            );
+                            )
+                        }),
+                );
+            }
 
             // Place excerpt headers above custom blocks on the same row.
             blocks_in_edit.sort_unstable_by(|(row_a, block_a), (row_b, block_b)| {