Add a test for editing a file of a branch checked out in another worktree

If you enter a branch in the branches panel, and that branch is checked
out in another worktree, pressing `e` on a line of a commit's diff opens
the file in the current worktree. The same happens for `e` on a file in
the commit files panel entered from there. The current worktree may not
have the file at all, as in this test, or have it in a different state
than the branch has it. The line number is carried forward to the
current worktree's version of the file too, and this gives line 0 here.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

pkg/integration/tests/test_list.go

@@ -694,6 +694,7 @@ var tests = []*components.IntegrationTest{
 	worktree.DetachWorktreeFromBranch,
 	worktree.DotfileBareRepo,
 	worktree.DoubleNestedLinkedSubmodule,
+	worktree.EditFileOfBranchInOtherWorktree,
 	worktree.ExcludeFileInWorktree,
 	worktree.FastForwardWorktreeBranch,
 	worktree.FastForwardWorktreeBranchShouldNotPolluteCurrentWorktree,

pkg/integration/tests/worktree/edit_file_of_branch_in_other_worktree.go

@@ -0,0 +1,77 @@
+package worktree
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+)
+
+var EditFileOfBranchInOtherWorktree = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Edit a file of a commit of a branch that is checked out in another worktree",
+	ExtraCmdArgs: []string{},
+	Skip:         false,
+	SetupConfig: func(config *config.AppConfig) {
+		config.GetUserConfig().Gui.UseHunkModeInDiffView = false
+		config.GetUserConfig().OS.Edit = "echo {{filename}} > edit-command"
+		config.GetUserConfig().OS.EditAtLine = "echo {{filename}}:{{line}} > edit-command"
+	},
+	SetupRepo: func(shell *Shell) {
+		shell.CreateFileAndAdd("README.md", "hello world")
+		shell.Commit("initial commit")
+		shell.NewBranch("mybranch")
+		shell.CreateFileAndAdd("file.txt", "1\n2\n3\n")
+		shell.Commit("add file")
+		shell.Checkout("master")
+		shell.AddWorktreeCheckout("mybranch", "../linked-worktree")
+
+		// Move the lines of the file down in the linked worktree, so that a line of
+		// the commit's diff is at a different line of the file there
+		shell.UpdateFile("../linked-worktree/file.txt", "0\n1\n2\n3\n")
+	},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		t.Views().Branches().
+			Focus().
+			Lines(
+				Contains("master").IsSelected(),
+				Contains("mybranch (worktree linked-worktree)"),
+			).
+			NavigateToLine(Contains("mybranch")).
+			PressEnter()
+
+		t.Views().SubCommits().
+			IsFocused().
+			Lines(
+				Contains("add file").IsSelected(),
+				Contains("initial commit"),
+			).
+			Press(keys.Universal.FocusMainView)
+
+		t.Views().Main().
+			IsFocused().
+			NavigateToLine(Contains("+2")).
+			Press(keys.Universal.Edit).
+			Tap(func() {
+				/* EXPECTED:
+				t.FileSystem().FileContent("edit-command", Contains("/linked-worktree/file.txt:3\n"))
+				ACTUAL: */
+				t.FileSystem().FileContent("edit-command", Contains("/repo/file.txt:0\n"))
+			}).
+			PressEscape()
+
+		t.Views().SubCommits().
+			IsFocused().
+			PressEnter()
+
+		t.Views().CommitFiles().
+			IsFocused().
+			Lines(
+				Contains("A file.txt").IsSelected(),
+			).
+			Press(keys.Universal.Edit).
+			Tap(func() {
+				/* EXPECTED:
+				t.FileSystem().FileContent("edit-command", Contains("/linked-worktree/file.txt\n"))
+				ACTUAL: */
+				t.FileSystem().FileContent("edit-command", Contains("/repo/file.txt\n"))
+			})
+	},
+})