kunchenguid--no-mistakes/internal/daemon/singleton_test.go

package daemon

import (
	"errors"
	"testing"

	"github.com/kunchenguid/no-mistakes/internal/db"
	"github.com/kunchenguid/no-mistakes/internal/paths"
)

// TestRunWithResources_SecondDaemonForSameRootFailsWithoutStealingSocket is
// the regression test for the duplicate-daemon wedge: v1.32.2's listen()
// unconditionally unlinked a live socket, so a second daemon starting
// against the same NM_HOME would steal the path and leave the first daemon
// alive but unreachable. With the singleton lock in place, a second
// RunWithResources call for the same root must fail fast (never reaching
// srv.Serve) and the first daemon must remain reachable throughout.
func TestRunWithResources_SecondDaemonForSameRootFailsWithoutStealingSocket(t *testing.T) {
	p, _ := startTestDaemon(t)

	if alive, err := daemonHealthCheck(p); err != nil || !alive {
		t.Fatalf("daemon 1 not healthy before second attempt: alive=%v err=%v", alive, err)
	}

	p2 := paths.WithRoot(p.Root())
	d2, err := db.Open(p2.DB())
	if err != nil {
		t.Fatal(err)
	}
	defer d2.Close()

	err = RunWithResources(p2, d2)
	if err == nil {
		t.Fatal("expected second RunWithResources against the same root to fail")
	}
	if !errors.Is(err, ErrSingletonLockHeld) {
		t.Fatalf("expected ErrSingletonLockHeld, got %v", err)
	}

	if alive, err := daemonHealthCheck(p); err != nil || !alive {
		t.Fatalf("daemon 1 became unreachable after the second attempt: alive=%v err=%v", alive, err)
	}
}