Add test for auto-forwarding branches that are checked out by another worktree

The test shows that we are currently auto-forwarding branches even if they are
checked out by another worktree; this is quite bad, because when you switch to
that other worktree you'll see that the files that are touched by the fetched
commits are all modified (which we don't test here).

pkg/integration/tests/sync/fetch_and_auto_forward_branches_all_branches_checked_out_in_other_worktree.go

@@ -0,0 +1,60 @@
+package sync
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+)
+
+var FetchAndAutoForwardBranchesAllBranchesCheckedOutInOtherWorktree = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Fetch from remote and auto-forward branches with config set to 'allBranches'; check that this skips branches checked out by another worktree",
+	ExtraCmdArgs: []string{},
+	Skip:         false,
+	SetupConfig: func(config *config.AppConfig) {
+		config.GetUserConfig().Git.AutoForwardBranches = "allBranches"
+		config.GetUserConfig().Git.LocalBranchSortOrder = "alphabetical"
+	},
+	SetupRepo: func(shell *Shell) {
+		shell.CreateNCommits(3)
+		shell.NewBranch("feature")
+		shell.NewBranch("diverged")
+		shell.CloneIntoRemote("origin")
+		shell.SetBranchUpstream("master", "origin/master")
+		shell.SetBranchUpstream("feature", "origin/feature")
+		shell.SetBranchUpstream("diverged", "origin/diverged")
+		shell.Checkout("master")
+		shell.HardReset("HEAD^")
+		shell.Checkout("feature")
+		shell.HardReset("HEAD~2")
+		shell.Checkout("diverged")
+		shell.HardReset("HEAD~2")
+		shell.EmptyCommit("local")
+		shell.NewBranch("checked-out")
+
+		shell.AddWorktreeCheckout("master", "../linked-worktree")
+	},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		t.Views().Branches().
+			Lines(
+				Contains("checked-out").IsSelected(),
+				Contains("diverged ↓2↑1"),
+				Contains("feature ↓2").DoesNotContain("↑"),
+				Contains("master (worktree) ↓1").DoesNotContain("↑"),
+			)
+
+		t.Views().Files().
+			IsFocused().
+			Press(keys.Files.Fetch)
+
+		// AutoForwardBranches is "allBranches": both master and feature get forwarded
+		t.Views().Branches().
+			Lines(
+				Contains("checked-out").IsSelected(),
+				Contains("diverged ↓2↑1"),
+				Contains("feature ✓"),
+				/* EXPECTED:
+				Contains("master (worktree) ↓1"),
+				ACTUAL: */
+				Contains("master (worktree) ✓"),
+			)
+	},
+})

pkg/integration/tests/test_list.go

@@ -383,6 +383,7 @@ var tests = []*components.IntegrationTest{
 	submodule.Reset,
 	submodule.ResetFolder,
 	sync.FetchAndAutoForwardBranchesAllBranches,
+	sync.FetchAndAutoForwardBranchesAllBranchesCheckedOutInOtherWorktree,
 	sync.FetchAndAutoForwardBranchesNone,
 	sync.FetchAndAutoForwardBranchesOnlyMainBranches,
 	sync.FetchPrune,