Show the number of lines changed per file in working file tree view (#4015)

- **PR Description**
Implements Issue #3643
Adds the number of line changes to the end of each file line in the
Files view.
Also adds the possibility for the user to enable and disable this
feature through the UserConfig.
<img width="323" alt="screenshot"
src="https://github.com/user-attachments/assets/6f818dd4-fbf5-49f2-b338-1b1fcc73f73a">

- **Please check if the PR fulfills these requirements**

* [x] Cheatsheets are up-to-date (run `go generate ./...`)
* [x] Code has been formatted (see
[here](https://github.com/jesseduffield/lazygit/blob/master/CONTRIBUTING.md#code-formatting))
* [x] Tests have been added/updated (see
[here](https://github.com/jesseduffield/lazygit/blob/master/pkg/integration/README.md)
for the integration test guide)
* [ ] Text is internationalised (see
[here](https://github.com/jesseduffield/lazygit/blob/master/CONTRIBUTING.md#internationalisation))
* [x] If a new UserConfig entry was added, make sure it can be
hot-reloaded (see
[here](https://github.com/jesseduffield/lazygit/blob/master/docs/dev/Codebase_Guide.md#using-userconfig))
* [ ] Docs have been updated if necessary
* [x] You've read through your own file changes for silly mistakes etc

docs/Config.md

@@ -164,6 +164,9 @@ gui:
   # This can be toggled from within Lazygit with the '~' key, but that will not change the default.
   showFileTree: true
 
+  # If true, show the number of lines changed per file in the Files view
+  showNumstatInFilesView: false
+
   # If true, show a random tip in the command log when Lazygit starts
   showRandomTip: true
 

pkg/commands/git_commands/file_loader.go

@@ -3,6 +3,7 @@ package git_commands
 import (
 	"fmt"
 	"path/filepath"
+	"strconv"
 	"strings"
 
 	"github.com/jesseduffield/lazygit/pkg/commands/models"
@@ -48,6 +49,14 @@ func (self *FileLoader) GetStatusFiles(opts GetStatusFileOptions) []*models.File
 	}
 	files := []*models.File{}
 
+	fileDiffs := map[string]FileDiff{}
+	if self.GitCommon.Common.UserConfig().Gui.ShowNumstatInFilesView {
+		fileDiffs, err = self.getFileDiffs()
+		if err != nil {
+			self.Log.Error(err)
+		}
+	}
+
 	for _, status := range statuses {
 		if strings.HasPrefix(status.StatusString, "warning") {
 			self.Log.Warningf("warning when calling git status: %s", status.StatusString)
@@ -60,6 +69,11 @@ func (self *FileLoader) GetStatusFiles(opts GetStatusFileOptions) []*models.File
 			DisplayString: status.StatusString,
 		}
 
+		if diff, ok := fileDiffs[status.Name]; ok {
+			file.LinesAdded = diff.LinesAdded
+			file.LinesDeleted = diff.LinesDeleted
+		}
+
 		models.SetStatusFields(file, status.Change)
 		files = append(files, file)
 	}
@@ -87,6 +101,45 @@ func (self *FileLoader) GetStatusFiles(opts GetStatusFileOptions) []*models.File
 	return files
 }
 
+type FileDiff struct {
+	LinesAdded   int
+	LinesDeleted int
+}
+
+func (fileLoader *FileLoader) getFileDiffs() (map[string]FileDiff, error) {
+	diffs, err := fileLoader.gitDiffNumStat()
+	if err != nil {
+		return nil, err
+	}
+
+	splitLines := strings.Split(diffs, "\x00")
+
+	fileDiffs := map[string]FileDiff{}
+	for _, line := range splitLines {
+		splitLine := strings.Split(line, "\t")
+		if len(splitLine) != 3 {
+			continue
+		}
+
+		linesAdded, err := strconv.Atoi(splitLine[0])
+		if err != nil {
+			continue
+		}
+		linesDeleted, err := strconv.Atoi(splitLine[1])
+		if err != nil {
+			continue
+		}
+
+		fileName := splitLine[2]
+		fileDiffs[fileName] = FileDiff{
+			LinesAdded:   linesAdded,
+			LinesDeleted: linesDeleted,
+		}
+	}
+
+	return fileDiffs, nil
+}
+
 // GitStatus returns the file status of the repo
 type GitStatusOptions struct {
 	NoRenames         bool
@@ -100,6 +153,16 @@ type FileStatus struct {
 	PreviousName string
 }
 
+func (fileLoader *FileLoader) gitDiffNumStat() (string, error) {
+	return fileLoader.cmd.New(
+		NewGitCmd("diff").
+			Arg("--numstat").
+			Arg("-z").
+			Arg("HEAD").
+			ToArgv(),
+	).DontLog().RunWithOutput()
+}
+
 func (self *FileLoader) gitStatus(opts GitStatusOptions) ([]FileStatus, error) {
 	cmdArgs := NewGitCmd("status").
 		Arg(opts.UntrackedFilesArg).

pkg/commands/git_commands/file_loader_test.go

@@ -11,29 +11,35 @@ import (
 
 func TestFileGetStatusFiles(t *testing.T) {
 	type scenario struct {
-		testName            string
-		similarityThreshold int
-		runner              oscommands.ICmdObjRunner
-		expectedFiles       []*models.File
+		testName               string
+		similarityThreshold    int
+		runner                 oscommands.ICmdObjRunner
+		showNumstatInFilesView bool
+		expectedFiles          []*models.File
 	}
 
 	scenarios := []scenario{
 		{
-			"No files found",
-			50,
-			oscommands.NewFakeRunner(t).
+			testName:            "No files found",
+			similarityThreshold: 50,
+			runner: oscommands.NewFakeRunner(t).
 				ExpectGitArgs([]string{"status", "--untracked-files=yes", "--porcelain", "-z", "--find-renames=50%"}, "", nil),
-			[]*models.File{},
+			expectedFiles: []*models.File{},
 		},
 		{
-			"Several files found",
-			50,
-			oscommands.NewFakeRunner(t).
+			testName:            "Several files found",
+			similarityThreshold: 50,
+			runner: oscommands.NewFakeRunner(t).
 				ExpectGitArgs([]string{"status", "--untracked-files=yes", "--porcelain", "-z", "--find-renames=50%"},
 					"MM file1.txt\x00A  file3.txt\x00AM file2.txt\x00?? file4.txt\x00UU file5.txt",
 					nil,
+				).
+				ExpectGitArgs([]string{"diff", "--numstat", "-z", "HEAD"},
+					"4\t1\tfile1.txt\x001\t0\tfile2.txt\x002\t2\tfile3.txt\x000\t2\tfile4.txt\x002\t2\tfile5.txt",
+					nil,
 				),
-			[]*models.File{
+			showNumstatInFilesView: true,
+			expectedFiles: []*models.File{
 				{
 					Name:                    "file1.txt",
 					HasStagedChanges:        true,
@@ -45,6 +51,8 @@ func TestFileGetStatusFiles(t *testing.T) {
 					HasInlineMergeConflicts: false,
 					DisplayString:           "MM file1.txt",
 					ShortStatus:             "MM",
+					LinesAdded:              4,
+					LinesDeleted:            1,
 				},
 				{
 					Name:                    "file3.txt",
@@ -57,6 +65,8 @@ func TestFileGetStatusFiles(t *testing.T) {
 					HasInlineMergeConflicts: false,
 					DisplayString:           "A  file3.txt",
 					ShortStatus:             "A ",
+					LinesAdded:              2,
+					LinesDeleted:            2,
 				},
 				{
 					Name:                    "file2.txt",
@@ -69,6 +79,8 @@ func TestFileGetStatusFiles(t *testing.T) {
 					HasInlineMergeConflicts: false,
 					DisplayString:           "AM file2.txt",
 					ShortStatus:             "AM",
+					LinesAdded:              1,
+					LinesDeleted:            0,
 				},
 				{
 					Name:                    "file4.txt",
@@ -81,6 +93,8 @@ func TestFileGetStatusFiles(t *testing.T) {
 					HasInlineMergeConflicts: false,
 					DisplayString:           "?? file4.txt",
 					ShortStatus:             "??",
+					LinesAdded:              0,
+					LinesDeleted:            2,
 				},
 				{
 					Name:                    "file5.txt",
@@ -93,15 +107,17 @@ func TestFileGetStatusFiles(t *testing.T) {
 					HasInlineMergeConflicts: true,
 					DisplayString:           "UU file5.txt",
 					ShortStatus:             "UU",
+					LinesAdded:              2,
+					LinesDeleted:            2,
 				},
 			},
 		},
 		{
-			"File with new line char",
-			50,
-			oscommands.NewFakeRunner(t).
+			testName:            "File with new line char",
+			similarityThreshold: 50,
+			runner: oscommands.NewFakeRunner(t).
 				ExpectGitArgs([]string{"status", "--untracked-files=yes", "--porcelain", "-z", "--find-renames=50%"}, "MM a\nb.txt", nil),
-			[]*models.File{
+			expectedFiles: []*models.File{
 				{
 					Name:                    "a\nb.txt",
 					HasStagedChanges:        true,
@@ -117,14 +133,14 @@ func TestFileGetStatusFiles(t *testing.T) {
 			},
 		},
 		{
-			"Renamed files",
-			50,
-			oscommands.NewFakeRunner(t).
+			testName:            "Renamed files",
+			similarityThreshold: 50,
+			runner: oscommands.NewFakeRunner(t).
 				ExpectGitArgs([]string{"status", "--untracked-files=yes", "--porcelain", "-z", "--find-renames=50%"},
 					"R  after1.txt\x00before1.txt\x00RM after2.txt\x00before2.txt",
 					nil,
 				),
-			[]*models.File{
+			expectedFiles: []*models.File{
 				{
 					Name:                    "after1.txt",
 					PreviousName:            "before1.txt",
@@ -154,14 +170,14 @@ func TestFileGetStatusFiles(t *testing.T) {
 			},
 		},
 		{
-			"File with arrow in name",
-			50,
-			oscommands.NewFakeRunner(t).
+			testName:            "File with arrow in name",
+			similarityThreshold: 50,
+			runner: oscommands.NewFakeRunner(t).
 				ExpectGitArgs([]string{"status", "--untracked-files=yes", "--porcelain", "-z", "--find-renames=50%"},
 					`?? a -> b.txt`,
 					nil,
 				),
-			[]*models.File{
+			expectedFiles: []*models.File{
 				{
 					Name:                    "a -> b.txt",
 					HasStagedChanges:        false,
@@ -185,8 +201,14 @@ func TestFileGetStatusFiles(t *testing.T) {
 			appState := &config.AppState{}
 			appState.RenameSimilarityThreshold = s.similarityThreshold
 
+			userConfig := &config.UserConfig{
+				Gui: config.GuiConfig{
+					ShowNumstatInFilesView: s.showNumstatInFilesView,
+				},
+			}
+
 			loader := &FileLoader{
-				GitCommon:   buildGitCommon(commonDeps{appState: appState}),
+				GitCommon:   buildGitCommon(commonDeps{appState: appState, userConfig: userConfig}),
 				cmd:         cmd,
 				config:      &FakeFileLoaderConfig{showUntrackedFiles: "yes"},
 				getFileType: func(string) string { return "file" },

pkg/commands/models/file.go

@@ -19,6 +19,8 @@ type File struct {
 	HasInlineMergeConflicts bool
 	DisplayString           string
 	ShortStatus             string // e.g. 'AD', ' A', 'M ', '??'
+	LinesDeleted            int
+	LinesAdded              int
 
 	// If true, this must be a worktree folder
 	IsWorktree bool

pkg/config/user_config.go

@@ -109,6 +109,8 @@ type GuiConfig struct {
 	// If true, display the files in the file views as a tree. If false, display the files as a flat list.
 	// This can be toggled from within Lazygit with the '~' key, but that will not change the default.
 	ShowFileTree bool `yaml:"showFileTree"`
+	// If true, show the number of lines changed per file in the Files view
+	ShowNumstatInFilesView bool `yaml:"showNumstatInFilesView"`
 	// If true, show a random tip in the command log when Lazygit starts
 	ShowRandomTip bool `yaml:"showRandomTip"`
 	// If true, show the command log
@@ -714,6 +716,7 @@ func GetDefaultConfig() *UserConfig {
 			ShowBottomLine:               true,
 			ShowPanelJumps:               true,
 			ShowFileTree:                 true,
+			ShowNumstatInFilesView:       false,
 			ShowRandomTip:                true,
 			ShowIcons:                    false,
 			NerdFontsVersion:             "",

pkg/gui/context/working_tree_context.go

@@ -30,7 +30,8 @@ func NewWorkingTreeContext(c *ContextCommon) *WorkingTreeContext {
 
 	getDisplayStrings := func(_ int, _ int) [][]string {
 		showFileIcons := icons.IsIconEnabled() && c.UserConfig().Gui.ShowFileIcons
-		lines := presentation.RenderFileTree(viewModel, c.Model().Submodules, showFileIcons)
+		showNumstat := c.UserConfig().Gui.ShowNumstatInFilesView
+		lines := presentation.RenderFileTree(viewModel, c.Model().Submodules, showFileIcons, showNumstat)
 		return lo.Map(lines, func(line string, _ int) []string {
 			return []string{line}
 		})

pkg/gui/presentation/files.go

@@ -22,12 +22,13 @@ func RenderFileTree(
 	tree filetree.IFileTree,
 	submoduleConfigs []*models.SubmoduleConfig,
 	showFileIcons bool,
+	showNumstat bool,
 ) []string {
 	collapsedPaths := tree.CollapsedPaths()
 	return renderAux(tree.GetRoot().Raw(), collapsedPaths, -1, -1, func(node *filetree.Node[models.File], treeDepth int, visualDepth int, isCollapsed bool) string {
 		fileNode := filetree.NewFileNode(node)
 
-		return getFileLine(isCollapsed, fileNode.GetHasUnstagedChanges(), fileNode.GetHasStagedChanges(), treeDepth, visualDepth, showFileIcons, submoduleConfigs, node)
+		return getFileLine(isCollapsed, fileNode.GetHasUnstagedChanges(), fileNode.GetHasStagedChanges(), treeDepth, visualDepth, showNumstat, showFileIcons, submoduleConfigs, node)
 	})
 }
 
@@ -111,6 +112,7 @@ func getFileLine(
 	hasStagedChanges bool,
 	treeDepth int,
 	visualDepth int,
+	showNumstat,
 	showFileIcons bool,
 	submoduleConfigs []*models.SubmoduleConfig,
 	node *filetree.Node[models.File],
@@ -165,6 +167,12 @@ func getFileLine(
 		output += theme.DefaultTextColor.Sprint(" (submodule)")
 	}
 
+	if file != nil && showNumstat {
+		if lineChanges := formatLineChanges(file.LinesAdded, file.LinesDeleted); lineChanges != "" {
+			output += " " + lineChanges
+		}
+	}
+
 	return output
 }
 
@@ -186,6 +194,23 @@ func formatFileStatus(file *models.File, restColor style.TextStyle) string {
 	return firstCharCl.Sprint(firstChar) + secondCharCl.Sprint(secondChar)
 }
 
+func formatLineChanges(linesAdded, linesDeleted int) string {
+	output := ""
+
+	if linesAdded != 0 {
+		output += style.FgGreen.Sprintf("+%d", linesAdded)
+	}
+
+	if linesDeleted != 0 {
+		if output != "" {
+			output += " "
+		}
+		output += style.FgRed.Sprintf("-%d", linesDeleted)
+	}
+
+	return output
+}
+
 func getCommitFileLine(
 	isCollapsed bool,
 	treeDepth int,

pkg/gui/presentation/files_test.go

@@ -19,11 +19,12 @@ func toStringSlice(str string) []string {
 
 func TestRenderFileTree(t *testing.T) {
 	scenarios := []struct {
-		name           string
-		root           *filetree.FileNode
-		files          []*models.File
-		collapsedPaths []string
-		expected       []string
+		name            string
+		root            *filetree.FileNode
+		files           []*models.File
+		collapsedPaths  []string
+		showLineChanges bool
+		expected        []string
 	}{
 		{
 			name:     "nil node",
@@ -37,6 +38,22 @@ func TestRenderFileTree(t *testing.T) {
 			},
 			expected: []string{" M test"},
 		},
+		{
+			name: "numstat",
+			files: []*models.File{
+				{Name: "test", ShortStatus: " M", HasStagedChanges: true, LinesAdded: 1, LinesDeleted: 1},
+				{Name: "test2", ShortStatus: " M", HasStagedChanges: true, LinesAdded: 1},
+				{Name: "test3", ShortStatus: " M", HasStagedChanges: true, LinesDeleted: 1},
+				{Name: "test4", ShortStatus: " M", HasStagedChanges: true, LinesAdded: 0, LinesDeleted: 0},
+			},
+			showLineChanges: true,
+			expected: []string{
+				" M test +1 -1",
+				" M test2 +1",
+				" M test3 -1",
+				" M test4",
+			},
+		},
 		{
 			name: "big example",
 			files: []*models.File{
@@ -72,7 +89,7 @@ M  file1
 			for _, path := range s.collapsedPaths {
 				viewModel.ToggleCollapsed(path)
 			}
-			result := RenderFileTree(viewModel, nil, false)
+			result := RenderFileTree(viewModel, nil, false, s.showLineChanges)
 			assert.EqualValues(t, s.expected, result)
 		})
 	}

schema/config.json

@@ -293,6 +293,11 @@
           "description": "If true, display the files in the file views as a tree. If false, display the files as a flat list.\nThis can be toggled from within Lazygit with the '~' key, but that will not change the default.",
           "default": true
         },
+        "showNumstatInFilesView": {
+          "type": "boolean",
+          "description": "If true, show the number of lines changed per file in the Files view",
+          "default": false
+        },
         "showRandomTip": {
           "type": "boolean",
           "description": "If true, show a random tip in the command log when Lazygit starts",