newt/updates/replace_test.go

package updates

import (
	"os"
	"path/filepath"
	"testing"
)

func TestReplaceBinary(t *testing.T) {
	dir := t.TempDir()
	exePath := filepath.Join(dir, "newt")
	newPath := filepath.Join(dir, ".newt-update-test")

	if err := os.WriteFile(exePath, []byte("old"), 0755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(newPath, []byte("new"), 0755); err != nil {
		t.Fatal(err)
	}

	if err := replaceBinary(newPath, exePath); err != nil {
		t.Fatalf("replaceBinary: %v", err)
	}

	got, err := os.ReadFile(exePath)
	if err != nil {
		t.Fatal(err)
	}
	if string(got) != "new" {
		t.Fatalf("expected new binary contents, got %q", got)
	}
	if _, err := os.Stat(newPath); !os.IsNotExist(err) {
		t.Fatalf("expected temp file to be consumed, stat err: %v", err)
	}

	removeStaleBinary(exePath)

	entries, err := os.ReadDir(dir)
	if err != nil {
		t.Fatal(err)
	}
	if len(entries) != 1 {
		t.Fatalf("expected only the installed binary to remain, got %d entries", len(entries))
	}
}