feat: add dependency shutdown and configurable service endpoints

lifecycle/controller_test.go

@@ -0,0 +1,67 @@
+package lifecycle
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"sync"
+	"testing"
+)
+
+func TestShutdownRetainsFirstFailure(t *testing.T) {
+	parent, signal := context.WithCancel(context.Background())
+	c := New(parent)
+	signal()
+	if c.Err() != nil {
+		t.Fatal("signal treated as failure")
+	}
+	first := errors.New("dependency stopped")
+	c.RequestShutdown(first)
+	var wg sync.WaitGroup
+	for i := 0; i < 100; i++ {
+		wg.Add(1)
+		go func() { defer wg.Done(); c.RequestShutdown(errors.New("later")); c.RequestShutdown(nil); _ = c.Err() }()
+	}
+	wg.Wait()
+	if !errors.Is(c.Err(), first) || c.Context().Err() == nil {
+		t.Fatal(c.Err())
+	}
+}
+
+func TestShutdownBeforeServingAndParentCauses(t *testing.T) {
+	fatal := errors.New("initialization fault")
+	c := New(nil)
+	c.RequestShutdown(fatal)
+	if c.Context().Err() == nil || !errors.Is(Cause(c.Context()), fatal) || !errors.Is(c.Err(), fatal) {
+		t.Fatal("lost early shutdown")
+	}
+	c.RequestShutdown(nil)
+	if !errors.Is(c.Err(), fatal) {
+		t.Fatal("cleanup erased failure")
+	}
+	parent, cancel := context.WithCancelCause(context.Background())
+	child := New(parent)
+	cancel(fatal)
+	if !errors.Is(child.Err(), fatal) {
+		t.Fatal("lost parent failure")
+	}
+	normal := New(nil)
+	normal.RequestShutdown(nil)
+	if normal.Err() != nil {
+		t.Fatal(normal.Err())
+	}
+}
+
+func TestCancellationCompatibleCauseAndExplicitFailure(t *testing.T) {
+	cause := fmt.Errorf("stop: %w", context.Canceled)
+	ctx, cancel := context.WithCancelCause(context.Background())
+	cancel(cause)
+	if Cause(ctx) != nil {
+		t.Fatal("cancellation-compatible stop treated as a fault")
+	}
+	c := New(nil)
+	c.RequestShutdown(cause)
+	if !errors.Is(c.Err(), cause) {
+		t.Fatal("explicit dependency failure suppressed")
+	}
+}