Add a test showing that a checkout before bisecting doesn't update the log

Once a bisect has started, the commits view shows the log of the branch
that was checked out when it started. This happens even while we don't
know both a good and a bad commit yet, and git hasn't checked out
anything for the user to test. If the user checks out a different
branch to mark its head as bad, the commits view keeps showing the old
branch, so the new branch's head isn't there to be marked.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

pkg/integration/tests/bisect/check_out_branch_before_bisecting.go

@@ -0,0 +1,62 @@
+package bisect
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+)
+
+var CheckOutBranchBeforeBisecting = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Check out a different branch after marking a commit as good, but before marking one as bad",
+	ExtraCmdArgs: []string{},
+	Skip:         false,
+	SetupRepo: func(shell *Shell) {
+		shell.
+			CreateNCommits(3).
+			NewBranch("feature").
+			CreateNCommitsStartingAt(3, 4).
+			Checkout("master")
+	},
+	SetupConfig: func(cfg *config.AppConfig) {
+		cfg.GetUserConfig().Git.Log.ShowGraph = "never"
+	},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		t.Views().Commits().
+			Focus().
+			SelectedLine(Contains("CI commit-03")).
+			Press(keys.Commits.ViewBisectOptions).
+			Tap(func() {
+				t.ExpectPopup().Menu().Title(Equals("Bisect")).Select(MatchesRegexp(`Mark .* as good`)).Confirm()
+			}).
+			Lines(
+				Contains("CI commit-03").Contains("<-- good"),
+				Contains("CI commit-02"),
+				Contains("CI commit-01"),
+			)
+
+		t.Views().Branches().
+			Focus().
+			NavigateToLine(Contains("feature")).
+			PressPrimaryAction().
+			Lines(
+				Contains("* feature"),
+				Contains("master"),
+			)
+
+		t.Views().Commits().
+			/* EXPECTED:
+			Lines(
+				Contains("CI commit-06"),
+				Contains("CI commit-05"),
+				Contains("CI commit-04"),
+				Contains("CI commit-03").Contains("<-- good"),
+				Contains("CI commit-02"),
+				Contains("CI commit-01"),
+			)
+			ACTUAL: */
+			Lines(
+				Contains("CI commit-03").Contains("<-- good"),
+				Contains("CI commit-02"),
+				Contains("CI commit-01"),
+			)
+	},
+})

pkg/integration/tests/test_list.go

@@ -36,6 +36,7 @@ import (
 
 var tests = []*components.IntegrationTest{
 	bisect.Basic,
+	bisect.CheckOutBranchBeforeBisecting,
 	bisect.ChooseTerms,
 	bisect.FromOtherBranch,
 	bisect.SelectCurrentCommit,