Add regression test for resolving conflicts in a file without a trailing LF

The test shows that the last line of the file is lost.

pkg/integration/tests/conflicts/resolve_without_trailing_lf.go

@@ -0,0 +1,60 @@
+package conflicts
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+)
+
+var ResolveWithoutTrailingLf = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Regression test for resolving a merge conflict when the file doesn't have a trailing newline",
+	ExtraCmdArgs: []string{},
+	Skip:         false,
+	SetupConfig:  func(config *config.AppConfig) {},
+	SetupRepo: func(shell *Shell) {
+		shell.
+			NewBranch("branch1").
+			CreateFileAndAdd("file", "a\n\nno eol").
+			Commit("initial commit").
+			UpdateFileAndAdd("file", "a1\n\nno eol").
+			Commit("commit on branch1").
+			NewBranchFrom("branch2", "HEAD^").
+			UpdateFileAndAdd("file", "a2\n\nno eol").
+			Commit("commit on branch2").
+			Checkout("branch1").
+			RunCommandExpectError([]string{"git", "merge", "--no-edit", "branch2"})
+	},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		t.Views().Files().
+			IsFocused().
+			Lines(
+				Contains("UU file").IsSelected(),
+			).
+			PressEnter()
+
+		t.Views().MergeConflicts().
+			IsFocused().
+			SelectedLines(
+				Contains("<<<<<<< HEAD"),
+				Contains("a1"),
+				Contains("======="),
+			).
+			SelectNextItem().
+			PressPrimaryAction()
+
+		t.ExpectPopup().Alert().
+			Title(Equals("Continue")).
+			Content(Contains("All merge conflicts resolved. Continue?")).
+			Cancel()
+
+		t.Views().Files().
+			Focus().
+			Lines(
+				Contains("M  file").IsSelected(),
+			)
+
+		/* EXPECTED:
+		t.Views().Main().Content(Contains("-a1\n+a2\n").DoesNotContain("-no eol"))
+		ACTUAL: */
+		t.Views().Main().Content(Contains("-a1\n+a2\n").Contains("-no eol"))
+	},
+})

pkg/integration/tests/test_list.go

@@ -123,6 +123,7 @@ var tests = []*components.IntegrationTest{
 	conflicts.ResolveExternally,
 	conflicts.ResolveMultipleFiles,
 	conflicts.ResolveNoAutoStage,
+	conflicts.ResolveWithoutTrailingLf,
 	conflicts.UndoChooseHunk,
 	custom_commands.AccessCommitProperties,
 	custom_commands.BasicCommand,