Add a test for switching tabs twice in rapid succession

If two tab switches are handled before the next layout, and the first
tab shows a diff in the main view while the second one shows a message,
the main view ends up showing the diff.

A diff's task is only created after the layout, since the layout
settles the width that the diff is laid out to. A message's task is
created right away. So the diff's task is created after the message's,
and replaces it.

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

pkg/integration/tests/main_view/show_the_tab_switched_to_last.go

@@ -0,0 +1,42 @@
+package main_view
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+)
+
+// Both tab switches are handled before the next layout. Switching to the Files tab
+// asks for the file's diff, whose task is only created after the layout; switching
+// back to the Worktrees tab asks for the worktree's details, whose task is created
+// right away. The main view has to show what was asked for last.
+var ShowTheTabSwitchedToLast = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Switching tabs twice in rapid succession leaves the main view showing the second tab's content",
+	ExtraCmdArgs: []string{},
+	Skip:         false,
+	SetupConfig:  func(config *config.AppConfig) {},
+	SetupRepo: func(shell *Shell) {
+		shell.CreateFileAndAdd("file1", "one\n")
+		shell.Commit("one")
+		shell.UpdateFile("file1", "ONE\n")
+	},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		t.Views().Worktrees().
+			Focus().
+			Lines(
+				Contains("(main worktree)").IsSelected(),
+			)
+
+		t.Views().Main().
+			Content(Contains("Path:"))
+
+		t.Views().Worktrees().
+			PressRapidly(keys.Universal.PrevTab, keys.Universal.NextTab).
+			IsFocused()
+
+		t.Views().Main().
+			/* EXPECTED:
+			Content(Contains("Path:"))
+			ACTUAL: */
+			Content(Contains("diff --git a/file1 b/file1"))
+	},
+})

pkg/integration/tests/test_list.go

@@ -480,6 +480,7 @@ var tests = []*components.IntegrationTest{
 	main_view.SelectionCommandTooltipsFollowTheDiff,
 	main_view.SelectionCommandsOnlyWhereTheyApply,
 	main_view.SelectionOverTheCustomPatch,
+	main_view.ShowTheTabSwitchedToLast,
 	main_view.StageDeletedFile,
 	main_view.StageDiffLines,
 	main_view.StageDiffLinesOfAPathWithASpace,