Implement lifecycle interfaces for Core services (#33)

* Implement Startable and Stoppable lifecycle interfaces

* Refactor tests: remove redundant method overrides in MockLifecycle

---------

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

core.go

@@ -30,12 +30,7 @@ func New(opts ...Option) (*Core, error) {
 			return nil, err
 		}
 	}
-	c.once.Do(func() {
-		c.initErr = nil
-	})
-	if c.initErr != nil {
-		return nil, c.initErr
-	}
+
 	if c.serviceLock {
 		c.servicesLocked = true
 	}
@@ -138,13 +133,43 @@ func WithServiceLock() Option {
 // ServiceStartup is the entry point for the Core service's startup lifecycle.
 // It is called by Wails when the application starts.
 func (c *Core) ServiceStartup(ctx context.Context, options application.ServiceOptions) error {
-	return c.ACTION(ActionServiceStartup{})
+	c.serviceMu.RLock()
+	startables := append([]Startable(nil), c.startables...)
+	c.serviceMu.RUnlock()
+
+	var agg error
+	for _, s := range startables {
+		if err := s.OnStartup(ctx); err != nil {
+			agg = errors.Join(agg, err)
+		}
+	}
+
+	if err := c.ACTION(ActionServiceStartup{}); err != nil {
+		agg = errors.Join(agg, err)
+	}
+
+	return agg
 }
 
 // ServiceShutdown is the entry point for the Core service's shutdown lifecycle.
 // It is called by Wails when the application shuts down.
 func (c *Core) ServiceShutdown(ctx context.Context) error {
-	return c.ACTION(ActionServiceShutdown{})
+	var agg error
+	if err := c.ACTION(ActionServiceShutdown{}); err != nil {
+		agg = errors.Join(agg, err)
+	}
+
+	c.serviceMu.RLock()
+	stoppables := append([]Stoppable(nil), c.stoppables...)
+	c.serviceMu.RUnlock()
+
+	for i := len(stoppables) - 1; i >= 0; i-- {
+		if err := stoppables[i].OnShutdown(ctx); err != nil {
+			agg = errors.Join(agg, err)
+		}
+	}
+
+	return agg
 }
 
 // ACTION dispatches a message to all registered IPC handlers.
@@ -191,6 +216,14 @@ func (c *Core) RegisterService(name string, api any) error {
 		return fmt.Errorf("core: service %q already registered", name)
 	}
 	c.services[name] = api
+
+	if s, ok := api.(Startable); ok {
+		c.startables = append(c.startables, s)
+	}
+	if s, ok := api.(Stoppable); ok {
+		c.stoppables = append(c.stoppables, s)
+	}
+
 	return nil
 }
 

core_extra_test.go

@@ -0,0 +1,43 @@
+package core
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type MockServiceWithIPC struct {
+	MockService
+	handled bool
+}
+
+func (m *MockServiceWithIPC) HandleIPCEvents(c *Core, msg Message) error {
+	m.handled = true
+	return nil
+}
+
+func TestCore_WithService_IPC(t *testing.T) {
+	svc := &MockServiceWithIPC{MockService: MockService{Name: "ipc-service"}}
+	factory := func(c *Core) (any, error) {
+		return svc, nil
+	}
+	c, err := New(WithService(factory))
+	assert.NoError(t, err)
+
+	// Trigger ACTION to verify handler was registered
+	err = c.ACTION(nil)
+	assert.NoError(t, err)
+	assert.True(t, svc.handled)
+}
+
+func TestCore_ACTION_Bad(t *testing.T) {
+	c, err := New()
+	assert.NoError(t, err)
+	errHandler := func(c *Core, msg Message) error {
+		return assert.AnError
+	}
+	c.RegisterAction(errHandler)
+	err = c.ACTION(nil)
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), assert.AnError.Error())
+}

core_lifecycle_test.go

@@ -0,0 +1,164 @@
+package core
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/wailsapp/wails/v3/pkg/application"
+)
+
+type MockStartable struct {
+	started bool
+	err     error
+}
+
+func (m *MockStartable) OnStartup(ctx context.Context) error {
+	m.started = true
+	return m.err
+}
+
+type MockStoppable struct {
+	stopped bool
+	err     error
+}
+
+func (m *MockStoppable) OnShutdown(ctx context.Context) error {
+	m.stopped = true
+	return m.err
+}
+
+type MockLifecycle struct {
+	MockStartable
+	MockStoppable
+}
+
+func TestCore_LifecycleInterfaces(t *testing.T) {
+	c, err := New()
+	assert.NoError(t, err)
+
+	startable := &MockStartable{}
+	stoppable := &MockStoppable{}
+	lifecycle := &MockLifecycle{}
+
+	// Register services
+	err = c.RegisterService("startable", startable)
+	assert.NoError(t, err)
+	err = c.RegisterService("stoppable", stoppable)
+	assert.NoError(t, err)
+	err = c.RegisterService("lifecycle", lifecycle)
+	assert.NoError(t, err)
+
+	// Startup
+	err = c.ServiceStartup(context.Background(), application.ServiceOptions{})
+	assert.NoError(t, err)
+	assert.True(t, startable.started)
+	assert.True(t, lifecycle.started)
+	assert.False(t, stoppable.stopped)
+
+	// Shutdown
+	err = c.ServiceShutdown(context.Background())
+	assert.NoError(t, err)
+	assert.True(t, stoppable.stopped)
+	assert.True(t, lifecycle.stopped)
+}
+
+type MockLifecycleWithLog struct {
+	id  string
+	log *[]string
+}
+
+func (m *MockLifecycleWithLog) OnStartup(ctx context.Context) error {
+	*m.log = append(*m.log, "start-"+m.id)
+	return nil
+}
+
+func (m *MockLifecycleWithLog) OnShutdown(ctx context.Context) error {
+	*m.log = append(*m.log, "stop-"+m.id)
+	return nil
+}
+
+func TestCore_LifecycleOrder(t *testing.T) {
+	c, err := New()
+	assert.NoError(t, err)
+
+	var callOrder []string
+
+	s1 := &MockLifecycleWithLog{id: "1", log: &callOrder}
+	s2 := &MockLifecycleWithLog{id: "2", log: &callOrder}
+
+	err = c.RegisterService("s1", s1)
+	assert.NoError(t, err)
+	err = c.RegisterService("s2", s2)
+	assert.NoError(t, err)
+
+	// Startup
+	err = c.ServiceStartup(context.Background(), application.ServiceOptions{})
+	assert.NoError(t, err)
+	assert.Equal(t, []string{"start-1", "start-2"}, callOrder)
+
+	// Reset log
+	callOrder = nil
+
+	// Shutdown
+	err = c.ServiceShutdown(context.Background())
+	assert.NoError(t, err)
+	assert.Equal(t, []string{"stop-2", "stop-1"}, callOrder)
+}
+
+func TestCore_LifecycleErrors(t *testing.T) {
+	c, err := New()
+	assert.NoError(t, err)
+
+	s1 := &MockStartable{err: assert.AnError}
+	s2 := &MockStoppable{err: assert.AnError}
+
+	c.RegisterService("s1", s1)
+	c.RegisterService("s2", s2)
+
+	err = c.ServiceStartup(context.Background(), application.ServiceOptions{})
+	assert.Error(t, err)
+	assert.ErrorIs(t, err, assert.AnError)
+
+	err = c.ServiceShutdown(context.Background())
+	assert.Error(t, err)
+	assert.ErrorIs(t, err, assert.AnError)
+}
+
+func TestCore_LifecycleErrors_Aggregated(t *testing.T) {
+	c, err := New()
+	assert.NoError(t, err)
+
+	// Register action that fails
+	c.RegisterAction(func(c *Core, msg Message) error {
+		if _, ok := msg.(ActionServiceStartup); ok {
+			return errors.New("startup action error")
+		}
+		if _, ok := msg.(ActionServiceShutdown); ok {
+			return errors.New("shutdown action error")
+		}
+		return nil
+	})
+
+	// Register service that fails
+	s1 := &MockStartable{err: errors.New("startup service error")}
+	s2 := &MockStoppable{err: errors.New("shutdown service error")}
+
+	err = c.RegisterService("s1", s1)
+	assert.NoError(t, err)
+	err = c.RegisterService("s2", s2)
+	assert.NoError(t, err)
+
+	// Startup
+	err = c.ServiceStartup(context.Background(), application.ServiceOptions{})
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "startup action error")
+	assert.Contains(t, err.Error(), "startup service error")
+
+	// Shutdown
+	err = c.ServiceShutdown(context.Background())
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "shutdown action error")
+	assert.Contains(t, err.Error(), "shutdown service error")
+}

interfaces.go

@@ -1,6 +1,7 @@
 package core
 
 import (
+	"context"
 	"embed"
 	"io"
 	"sync"
@@ -46,6 +47,16 @@ type Option func(*Core) error
 // Any struct can be a message, allowing for structured data to be passed between services.
 type Message interface{}
 
+// Startable is an interface for services that need to perform initialization.
+type Startable interface {
+	OnStartup(ctx context.Context) error
+}
+
+// Stoppable is an interface for services that need to perform cleanup.
+type Stoppable interface {
+	OnShutdown(ctx context.Context) error
+}
+
 // Core is the central application object that manages services, assets, and communication.
 type Core struct {
 	once           sync.Once
@@ -59,6 +70,8 @@ type Core struct {
 	serviceMu      sync.RWMutex
 	services       map[string]any
 	servicesLocked bool
+	startables     []Startable
+	stoppables     []Stoppable
 }
 
 var instance *Core

runtime_pkg_extra_test.go

@@ -0,0 +1,18 @@
+package core
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNewWithFactories_EmptyName(t *testing.T) {
+	factories := map[string]ServiceFactory{
+		"": func() (any, error) {
+			return &MockService{Name: "test"}, nil
+		},
+	}
+	_, err := NewWithFactories(nil, factories)
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "service name cannot be empty")
+}