Add test for reverse-applying a patch that conflicts

The patch contains changes to two files; the first one conflicts, the second
doesn't. Note how it only applies changes to the first file at this point in the
branch; we'll fix this in the next commit.

This test would fail on master for multiple reasons.

pkg/integration/tests/patch_building/apply_in_reverse_with_conflict.go

@@ -0,0 +1,91 @@
+package patch_building
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+)
+
+var ApplyInReverseWithConflict = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Apply a custom patch in reverse, resulting in a conflict",
+	ExtraCmdArgs: "",
+	Skip:         false,
+	SetupConfig:  func(config *config.AppConfig) {},
+	SetupRepo: func(shell *Shell) {
+		shell.CreateFileAndAdd("file1", "file1 content\n")
+		shell.CreateFileAndAdd("file2", "file2 content\n")
+		shell.Commit("first commit")
+		shell.UpdateFileAndAdd("file1", "file1 content\nmore file1 content\n")
+		shell.UpdateFileAndAdd("file2", "file2 content\nmore file2 content\n")
+		shell.Commit("second commit")
+		shell.UpdateFileAndAdd("file1", "file1 content\nmore file1 content\neven more file1\n")
+		shell.Commit("third commit")
+	},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		t.Views().Commits().
+			Focus().
+			Lines(
+				Contains("third commit").IsSelected(),
+				Contains("second commit"),
+				Contains("first commit"),
+			).
+			NavigateToLine(Contains("second commit")).
+			PressEnter()
+
+		t.Views().CommitFiles().
+			IsFocused().
+			Lines(
+				Contains("M").Contains("file1").IsSelected(),
+				Contains("M").Contains("file2"),
+			).
+			// Add both files to the patch; the first will conflict, the second won't
+			PressPrimaryAction().
+			SelectNextItem().
+			PressPrimaryAction()
+
+		t.Views().Information().Content(Contains("building patch"))
+
+		t.Views().PatchBuildingSecondary().Content(
+			Contains("+more file1 content").Contains("+more file2 content"))
+
+		t.Common().SelectPatchOption(Contains("apply patch in reverse"))
+
+		t.ExpectPopup().Alert().
+			Title(Equals("Error")).
+			Content(Contains("Applied patch to 'file1' with conflicts.").
+				DoesNotContain("Applied patch to 'file2' cleanly.")).
+			Confirm()
+
+		t.Views().Files().
+			Focus().
+			Lines(
+				Contains("UU").Contains("file1").IsSelected(),
+			).
+			PressPrimaryAction()
+
+		t.Views().MergeConflicts().
+			IsFocused().
+			ContainsLines(
+				Contains("file1 content"),
+				Contains("<<<<<<< ours").IsSelected(),
+				Contains("more file1 content").IsSelected(),
+				Contains("even more file1").IsSelected(),
+				Contains("=======").IsSelected(),
+				Contains(">>>>>>> theirs"),
+			).
+			SelectNextItem().
+			PressPrimaryAction()
+
+		t.Views().Files().
+			Focus().
+			Lines(
+				Contains("M").Contains("file1").IsSelected(),
+			)
+
+		t.Views().Main().
+			ContainsLines(
+				Contains(" file1 content"),
+				Contains("-more file1 content"),
+				Contains("-even more file1"),
+			)
+	},
+})

pkg/integration/tests/test_list.go

@@ -99,6 +99,7 @@ var tests = []*components.IntegrationTest{
 	misc.InitialOpen,
 	patch_building.Apply,
 	patch_building.ApplyInReverse,
+	patch_building.ApplyInReverseWithConflict,
 	patch_building.CopyPatchToClipboard,
 	patch_building.MoveToIndex,
 	patch_building.MoveToIndexPartial,