Add test for moving patch to index when there's a modified file

This is functionality that works already, we only add the test for more complete
test coverage. However, there's a detail problem, and the test demonstrates
this: we keep the stash even if there was no conflict. We'll fix this next.

Author: stefanhaller

pkg/integration/tests/patch_building/move_to_index_with_modified_file.go

@@ -0,0 +1,64 @@
+package patch_building
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+)
+
+var MoveToIndexWithModifiedFile = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Move a patch from a commit to the index, with a modified file in the working tree that conflicts with the patch",
+	ExtraCmdArgs: []string{},
+	Skip:         false,
+	SetupConfig:  func(config *config.AppConfig) {},
+	SetupRepo: func(shell *Shell) {
+		shell.CreateFileAndAdd("file1", "1\n2\n3\n4\n")
+		shell.Commit("first commit")
+		shell.UpdateFileAndAdd("file1", "11\n2\n3\n4\n")
+		shell.Commit("second commit")
+		shell.UpdateFile("file1", "111\n2\n3\n4\n")
+	},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		t.Views().Commits().
+			Focus().
+			Lines(
+				Contains("second commit").IsSelected(),
+				Contains("first commit"),
+			).
+			PressEnter()
+
+		t.Views().CommitFiles().
+			IsFocused().
+			Lines(
+				Equals("M file1"),
+			).
+			PressPrimaryAction()
+
+		t.Views().Information().Content(Contains("Building patch"))
+
+		t.Views().Secondary().Content(Contains("-1\n+11"))
+
+		t.Common().SelectPatchOption(Contains("Move patch out into index"))
+
+		t.ExpectPopup().Confirmation().Title(Equals("Must stash")).
+			Content(Contains("Pulling a patch out into the index requires stashing and unstashing your changes.")).
+			Confirm()
+
+		t.Views().Files().
+			Focus().
+			Lines(
+				Equals("MM file1"),
+			)
+
+		t.Views().Main().
+			Content(Contains("-11\n+111\n"))
+		t.Views().Secondary().
+			Content(Contains("-1\n+11\n"))
+
+		/* EXPECTED:
+		t.Views().Stash().IsEmpty()
+		ACTUAL: */
+		t.Views().Stash().Lines(
+			Contains("Auto-stashing changes"),
+		)
+	},
+})

pkg/integration/tests/test_list.go

@@ -310,6 +310,7 @@ var tests = []*components.IntegrationTest{
 	patch_building.MoveToIndexPartOfAdjacentAddedLines,
 	patch_building.MoveToIndexPartial,
 	patch_building.MoveToIndexWithConflict,
+	patch_building.MoveToIndexWithModifiedFile,
 	patch_building.MoveToIndexWorksEvenIfNoprefixIsSet,
 	patch_building.MoveToLaterCommit,
 	patch_building.MoveToLaterCommitPartialHunk,