Merge branch 'main' of github.com:bitechdev/ResolveSpec into server

pkg/logger/logger.go

@@ -75,6 +75,25 @@ func CloseErrorTracking() error {
 	return nil
 }
 
+// extractContext attempts to find a context.Context in the given arguments.
+// It returns the found context (or context.Background() if not found) and
+// the remaining arguments without the context.
+func extractContext(args ...interface{}) (context.Context, []interface{}) {
+	ctx := context.Background()
+	var newArgs []interface{}
+	found := false
+
+	for _, arg := range args {
+		if c, ok := arg.(context.Context); ok && !found {
+			ctx = c
+			found = true
+		} else {
+			newArgs = append(newArgs, arg)
+		}
+	}
+	return ctx, newArgs
+}
+
 func Info(template string, args ...interface{}) {
 	if Logger == nil {
 		log.Printf(template, args...)
@@ -84,7 +103,8 @@ func Info(template string, args ...interface{}) {
 }
 
 func Warn(template string, args ...interface{}) {
-	message := fmt.Sprintf(template, args...)
+	ctx, remainingArgs := extractContext(args...)
+	message := fmt.Sprintf(template, remainingArgs...)
 	if Logger == nil {
 		log.Printf("%s", message)
 	} else {
@@ -93,14 +113,15 @@ func Warn(template string, args ...interface{}) {
 
 	// Send to error tracker
 	if errorTracker != nil {
-		errorTracker.CaptureMessage(context.Background(), message, errortracking.SeverityWarning, map[string]interface{}{
+		errorTracker.CaptureMessage(ctx, message, errortracking.SeverityWarning, map[string]interface{}{
 			"process_id": os.Getpid(),
 		})
 	}
 }
 
 func Error(template string, args ...interface{}) {
-	message := fmt.Sprintf(template, args...)
+	ctx, remainingArgs := extractContext(args...)
+	message := fmt.Sprintf(template, remainingArgs...)
 	if Logger == nil {
 		log.Printf("%s", message)
 	} else {
@@ -109,7 +130,7 @@ func Error(template string, args ...interface{}) {
 
 	// Send to error tracker
 	if errorTracker != nil {
-		errorTracker.CaptureMessage(context.Background(), message, errortracking.SeverityError, map[string]interface{}{
+		errorTracker.CaptureMessage(ctx, message, errortracking.SeverityError, map[string]interface{}{
 			"process_id": os.Getpid(),
 		})
 	}
@@ -124,12 +145,13 @@ func Debug(template string, args ...interface{}) {
 }
 
 // CatchPanic - Handle panic
-func CatchPanicCallback(location string, cb func(err any)) {
+func CatchPanicCallback(location string, cb func(err any), args ...interface{}) {
+	ctx, _ := extractContext(args...)
 	if err := recover(); err != nil {
 		callstack := debug.Stack()
 
 		if Logger != nil {
-			Error("Panic in %s : %v", location, err)
+			Error("Panic in %s : %v", location, err, ctx) // Pass context implicitly
 		} else {
 			fmt.Printf("%s:PANIC->%+v", location, err)
 			debug.PrintStack()
@@ -137,7 +159,7 @@ func CatchPanicCallback(location string, cb func(err any)) {
 
 		// Send to error tracker
 		if errorTracker != nil {
-			errorTracker.CapturePanic(context.Background(), err, callstack, map[string]interface{}{
+			errorTracker.CapturePanic(ctx, err, callstack, map[string]interface{}{
 				"location":   location,
 				"process_id": os.Getpid(),
 			})
@@ -150,8 +172,8 @@ func CatchPanicCallback(location string, cb func(err any)) {
 }
 
 // CatchPanic - Handle panic
-func CatchPanic(location string) {
-	CatchPanicCallback(location, nil)
+func CatchPanic(location string, args ...interface{}) {
+	CatchPanicCallback(location, nil, args...)
 }
 
 // HandlePanic logs a panic and returns it as an error
@@ -163,13 +185,14 @@ func CatchPanic(location string) {
 //	        err = logger.HandlePanic("MethodName", r)
 //	    }
 //	}()
-func HandlePanic(methodName string, r any) error {
+func HandlePanic(methodName string, r any, args ...interface{}) error {
+	ctx, _ := extractContext(args...)
 	stack := debug.Stack()
-	Error("Panic in %s: %v\nStack trace:\n%s", methodName, r, string(stack))
+	Error("Panic in %s: %v\nStack trace:\n%s", methodName, r, string(stack), ctx) // Pass context implicitly
 
 	// Send to error tracker
 	if errorTracker != nil {
-		errorTracker.CapturePanic(context.Background(), r, stack, map[string]interface{}{
+		errorTracker.CapturePanic(ctx, r, stack, map[string]interface{}{
 			"method":     methodName,
 			"process_id": os.Getpid(),
 		})

pkg/metrics/interfaces.go

@@ -39,6 +39,9 @@ type Provider interface {
 	// UpdateEventQueueSize updates the event queue size metric
 	UpdateEventQueueSize(size int64)
 
+	// RecordPanic records a panic event
+	RecordPanic(methodName string)
+
 	// Handler returns an HTTP handler for exposing metrics (e.g., /metrics endpoint)
 	Handler() http.Handler
 }
@@ -75,6 +78,7 @@ func (n *NoOpProvider) RecordEventPublished(source, eventType string) {}
 func (n *NoOpProvider) RecordEventProcessed(source, eventType, status string, duration time.Duration) {
 }
 func (n *NoOpProvider) UpdateEventQueueSize(size int64) {}
+func (n *NoOpProvider) RecordPanic(methodName string)   {}
 func (n *NoOpProvider) Handler() http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusNotFound)

pkg/metrics/prometheus.go

@@ -20,6 +20,7 @@ type PrometheusProvider struct {
 	cacheHits        *prometheus.CounterVec
 	cacheMisses      *prometheus.CounterVec
 	cacheSize        *prometheus.GaugeVec
+	panicsTotal      *prometheus.CounterVec
 }
 
 // NewPrometheusProvider creates a new Prometheus metrics provider
@@ -83,6 +84,13 @@ func NewPrometheusProvider() *PrometheusProvider {
 			},
 			[]string{"provider"},
 		),
+		panicsTotal: promauto.NewCounterVec(
+			prometheus.CounterOpts{
+				Name: "panics_total",
+				Help: "Total number of panics",
+			},
+			[]string{"method"},
+		),
 	}
 }
 
@@ -145,6 +153,11 @@ func (p *PrometheusProvider) UpdateCacheSize(provider string, size int64) {
 	p.cacheSize.WithLabelValues(provider).Set(float64(size))
 }
 
+// RecordPanic implements the Provider interface
+func (p *PrometheusProvider) RecordPanic(methodName string) {
+	p.panicsTotal.WithLabelValues(methodName).Inc()
+}
+
 // Handler implements Provider interface
 func (p *PrometheusProvider) Handler() http.Handler {
 	return promhttp.Handler()

pkg/middleware/panic.go

@@ -0,0 +1,33 @@
+package middleware
+
+import (
+	"net/http"
+
+	"github.com/bitechdev/ResolveSpec/pkg/logger"
+	"github.com/bitechdev/ResolveSpec/pkg/metrics"
+)
+
+const panicMiddlewareMethodName = "PanicMiddleware"
+
+// PanicRecovery is a middleware that recovers from panics, logs the error,
+// sends it to an error tracker, records a metric, and returns a 500 Internal Server Error.
+func PanicRecovery(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		defer func() {
+			if rcv := recover(); rcv != nil {
+				// Record the panic metric
+				metrics.GetProvider().RecordPanic(panicMiddlewareMethodName)
+
+				// Log the panic and send to error tracker
+				// We pass the request context so the error tracker can potentially
+				// link the panic to the request trace.
+				ctx := r.Context()
+				err := logger.HandlePanic(panicMiddlewareMethodName, rcv, ctx)
+
+				// Respond with a 500 error
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+			}
+		}()
+		next.ServeHTTP(w, r)
+	})
+}

pkg/middleware/panic_test.go

@@ -0,0 +1,86 @@
+package middleware
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/bitechdev/ResolveSpec/pkg/logger"
+	"github.com/bitechdev/ResolveSpec/pkg/metrics"
+	"github.com/stretchr/testify/assert"
+)
+
+// mockMetricsProvider is a mock for the metrics provider to check if methods are called.
+type mockMetricsProvider struct {
+	metrics.NoOpProvider // Embed NoOpProvider to avoid implementing all methods
+	panicRecorded bool
+	methodName    string
+}
+
+func (m *mockMetricsProvider) RecordPanic(methodName string) {
+	m.panicRecorded = true
+	m.methodName = methodName
+}
+
+func TestPanicRecovery(t *testing.T) {
+	// Initialize a mock logger to avoid actual logging output during tests
+	logger.Init(true)
+
+	// Setup mock metrics provider
+	mockProvider := &mockMetricsProvider{}
+	originalProvider := metrics.GetProvider()
+	metrics.SetProvider(mockProvider)
+	defer metrics.SetProvider(originalProvider) // Restore original provider after test
+
+	// 1. Test case: A handler that panics
+	t.Run("recovers from panic and returns 500", func(t *testing.T) {
+		// Reset mock state for this sub-test
+		mockProvider.panicRecorded = false
+		mockProvider.methodName = ""
+
+		panicHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			panic("something went terribly wrong")
+		})
+
+		// Create the middleware wrapping the panicking handler
+		testHandler := PanicRecovery(panicHandler)
+
+		// Create a test request and response recorder
+		req := httptest.NewRequest("GET", "http://example.com/foo", nil)
+		rr := httptest.NewRecorder()
+
+		// Serve the request
+		testHandler.ServeHTTP(rr, req)
+
+		// Assertions
+		assert.Equal(t, http.StatusInternalServerError, rr.Code, "expected status code to be 500")
+		assert.Contains(t, rr.Body.String(), "panic in PanicMiddleware: something went terribly wrong", "expected error message in response body")
+
+		// Assert that the metric was recorded
+		assert.True(t, mockProvider.panicRecorded, "expected RecordPanic to be called on metrics provider")
+		assert.Equal(t, panicMiddlewareMethodName, mockProvider.methodName, "expected panic to be recorded with the correct method name")
+	})
+
+	// 2. Test case: A handler that does NOT panic
+	t.Run("does not interfere with a non-panicking handler", func(t *testing.T) {
+		// Reset mock state for this sub-test
+		mockProvider.panicRecorded = false
+
+		successHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.WriteHeader(http.StatusOK)
+			w.Write([]byte("OK"))
+		})
+
+		testHandler := PanicRecovery(successHandler)
+
+		req := httptest.NewRequest("GET", "http://example.com/foo", nil)
+		rr := httptest.NewRecorder()
+
+		testHandler.ServeHTTP(rr, req)
+
+		// Assertions
+		assert.Equal(t, http.StatusOK, rr.Code, "expected status code to be 200")
+		assert.Equal(t, "OK", rr.Body.String(), "expected 'OK' response body")
+		assert.False(t, mockProvider.panicRecorded, "expected RecordPanic to not be called when there is no panic")
+	})
+}

pkg/server/interfaces.go

@@ -0,0 +1,52 @@
+package server
+
+import (
+	"context"
+	"net/http"
+)
+
+// Config holds the configuration for a single web server instance.
+type Config struct {
+	Name        string
+	Host        string
+	Port        int
+	Description string
+	SSLCert     string
+	SSLKey      string
+	GZIP        bool
+	// Handler is the http.Handler (e.g., a router) to be served.
+	Handler http.Handler
+}
+
+// Instance defines the interface for a single server instance.
+// It abstracts the underlying http.Server, allowing for easier management and testing.
+type Instance interface {
+	// Start begins serving requests. This method should be non-blocking and
+	// run the server in a separate goroutine.
+	Start() error
+	// Stop gracefully shuts down the server without interrupting any active connections.
+	// It accepts a context to allow for a timeout.
+	Stop(ctx context.Context) error
+	// Addr returns the network address the server is listening on.
+	Addr() string
+}
+
+// Manager defines the interface for a server manager.
+// It is responsible for managing the lifecycle of multiple server instances.
+type Manager interface {
+	// Add registers a new server instance based on the provided configuration.
+	// The server is not started until StartAll or Start is called on the instance.
+	Add(cfg Config) (Instance, error)
+	// Get returns a server instance by its name.
+	Get(name string) (Instance, error)
+	// Remove stops and removes a server instance by its name.
+	Remove(name string) error
+	// StartAll starts all registered server instances that are not already running.
+	StartAll() error
+	// StopAll gracefully shuts down all running server instances.
+	StopAll() error
+	// RestartAll gracefully restarts all running server instances.
+	RestartAll() error
+	// List returns all registered server instances.
+	List() []Instance
+}

pkg/server/manager.go

@@ -0,0 +1,282 @@
+package server
+
+import (
+	"context"
+	"crypto/tls"
+	"fmt"
+	"net/http"
+	"sync"
+	"time"
+
+	"github.com/bitechdev/ResolveSpec/pkg/logger"
+	"github.com/bitechdev/ResolveSpec/pkg/middleware"
+	"github.com/klauspost/compress/gzhttp"
+	"golang.org/x/net/http2"
+)
+
+// serverManager manages a collection of server instances.
+type serverManager struct {
+	instances map[string]Instance
+	mu        sync.RWMutex
+}
+
+// NewManager creates a new server manager.
+func NewManager() Manager {
+	return &serverManager{
+		instances: make(map[string]Instance),
+	}
+}
+
+// Add registers a new server instance.
+func (sm *serverManager) Add(cfg Config) (Instance, error) {
+	sm.mu.Lock()
+	defer sm.mu.Unlock()
+
+	if cfg.Name == "" {
+		return nil, fmt.Errorf("server name cannot be empty")
+	}
+	if _, exists := sm.instances[cfg.Name]; exists {
+		return nil, fmt.Errorf("server with name '%s' already exists", cfg.Name)
+	}
+
+	instance, err := newInstance(cfg)
+	if err != nil {
+		return nil, err
+	}
+
+	sm.instances[cfg.Name] = instance
+	return instance, nil
+}
+
+// Get returns a server instance by its name.
+func (sm *serverManager) Get(name string) (Instance, error) {
+	sm.mu.RLock()
+	defer sm.mu.RUnlock()
+
+	instance, exists := sm.instances[name]
+	if !exists {
+		return nil, fmt.Errorf("server with name '%s' not found", name)
+	}
+	return instance, nil
+}
+
+// Remove stops and removes a server instance by its name.
+func (sm *serverManager) Remove(name string) error {
+	sm.mu.Lock()
+	defer sm.mu.Unlock()
+
+	instance, exists := sm.instances[name]
+	if !exists {
+		return fmt.Errorf("server with name '%s' not found", name)
+	}
+
+	// Stop the server if it's running
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	if err := instance.Stop(ctx); err != nil {
+		logger.Warn("Failed to gracefully stop server '%s' on remove: %v", name, err, context.Background())
+	}
+
+	delete(sm.instances, name)
+	return nil
+}
+
+// StartAll starts all registered server instances.
+func (sm *serverManager) StartAll() error {
+	sm.mu.RLock()
+	defer sm.mu.RUnlock()
+
+	var startErrors []error
+	for name, instance := range sm.instances {
+		if err := instance.Start(); err != nil {
+			startErrors = append(startErrors, fmt.Errorf("failed to start server '%s': %w", name, err))
+		}
+	}
+
+	if len(startErrors) > 0 {
+		// In a real-world scenario, you might want a more sophisticated error handling strategy
+		return fmt.Errorf("encountered errors while starting servers: %v", startErrors)
+	}
+	return nil
+}
+
+// StopAll gracefully shuts down all running server instances.
+func (sm *serverManager) StopAll() error {
+	sm.mu.RLock()
+	instancesToStop := make([]Instance, 0, len(sm.instances))
+	for _, instance := range sm.instances {
+		instancesToStop = append(instancesToStop, instance)
+	}
+	sm.mu.RUnlock()
+
+	logger.Info("Shutting down all servers...", context.Background())
+
+	var shutdownErrors []error
+	var wg sync.WaitGroup
+
+	for _, instance := range instancesToStop {
+		wg.Add(1)
+		go func(inst Instance) {
+			defer wg.Done()
+			ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
+			defer cancel()
+			if err := inst.Stop(ctx); err != nil {
+				shutdownErrors = append(shutdownErrors, fmt.Errorf("failed to stop server '%s': %w", inst.Addr(), err))
+			}
+		}(instance)
+	}
+
+	wg.Wait()
+
+	if len(shutdownErrors) > 0 {
+		return fmt.Errorf("encountered errors while stopping servers: %v", shutdownErrors)
+	}
+	logger.Info("All servers stopped gracefully.", context.Background())
+	return nil
+}
+
+// RestartAll gracefully restarts all running server instances.
+func (sm *serverManager) RestartAll() error {
+	logger.Info("Restarting all servers...", context.Background())
+	if err := sm.StopAll(); err != nil {
+		return fmt.Errorf("failed to stop servers during restart: %w", err)
+	}
+
+	// Give ports time to be released
+	time.Sleep(200 * time.Millisecond)
+
+	if err := sm.StartAll(); err != nil {
+		return fmt.Errorf("failed to start servers during restart: %w", err)
+	}
+	logger.Info("All servers restarted successfully.", context.Background())
+	return nil
+}
+
+// List returns all registered server instances.
+func (sm *serverManager) List() []Instance {
+	sm.mu.RLock()
+	defer sm.mu.RUnlock()
+
+	instances := make([]Instance, 0, len(sm.instances))
+	for _, instance := range sm.instances {
+		instances = append(instances, instance)
+	}
+	return instances
+}
+
+// serverInstance is a concrete implementation of the Instance interface.
+type serverInstance struct {
+	cfg        Config
+	httpServer *http.Server
+	mu         sync.RWMutex
+	running    bool
+	stopCh     chan struct{}
+}
+
+// newInstance creates a new, unstarted server instance from a config.
+func newInstance(cfg Config) (*serverInstance, error) {
+	if cfg.Handler == nil {
+		return nil, fmt.Errorf("handler cannot be nil")
+	}
+
+	addr := fmt.Sprintf("%s:%d", cfg.Host, cfg.Port)
+	var handler http.Handler = cfg.Handler
+
+	// Wrap with GZIP handler if enabled
+	if cfg.GZIP {
+		gz, err := gzhttp.NewWrapper(gzhttp.BestSpeed)
+		if err != nil {
+			return nil, fmt.Errorf("failed to create GZIP wrapper: %w", err)
+		}
+		handler = gz(handler)
+	}
+
+	// Wrap with the panic recovery middleware
+	handler = middleware.PanicRecovery(handler)
+
+	// Here you could add other default middleware like request logging, metrics, etc.
+
+	httpServer := &http.Server{
+		Addr:         addr,
+		Handler:      handler,
+		ReadTimeout:  15 * time.Second,
+		WriteTimeout: 15 * time.Second,
+		IdleTimeout:  60 * time.Second,
+	}
+
+	return &serverInstance{
+		cfg:        cfg,
+		httpServer: httpServer,
+		stopCh:     make(chan struct{}),
+	}, nil
+}
+
+// Start begins serving requests in a new goroutine.
+func (s *serverInstance) Start() error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	if s.running {
+		return fmt.Errorf("server '%s' is already running", s.cfg.Name)
+	}
+
+	hasSSL := s.cfg.SSLCert != "" && s.cfg.SSLKey != ""
+
+	go func() {
+		defer func() {
+			s.mu.Lock()
+			s.running = false
+			s.mu.Unlock()
+			logger.Info("Server '%s' stopped.", s.cfg.Name, context.Background())
+		}()
+
+		var err error
+		protocol := "HTTP"
+
+		if hasSSL {
+			protocol = "HTTPS"
+			// Configure TLS + HTTP/2
+			s.httpServer.TLSConfig = &tls.Config{
+				MinVersion: tls.VersionTLS12,
+			}
+			            logger.Info("Starting %s server '%s' on %s", protocol, s.cfg.Name, s.Addr(), context.Background())			err = s.httpServer.ListenAndServeTLS(s.cfg.SSLCert, s.cfg.SSLKey)
+		} else {
+			logger.Info("Starting %s server '%s' on %s", protocol, s.cfg.Name, s.Addr(), context.Background())
+			err = s.httpServer.ListenAndServe()
+		}
+
+		// If the server stopped for a reason other than a graceful shutdown, log the error.
+		if err != nil && err != http.ErrServerClosed {
+			logger.Error("Server '%s' failed: %v", s.cfg.Name, err, context.Background())
+		}
+	}()
+
+	s.running = true
+	// A small delay to allow the goroutine to start and potentially fail on binding.
+	// A more robust solution might involve a channel signal.
+	time.Sleep(50 * time.Millisecond)
+
+	return nil
+}
+
+// Stop gracefully shuts down the server.
+func (s *serverInstance) Stop(ctx context.Context) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	if !s.running {
+		return nil // Already stopped
+	}
+
+	logger.Info("Gracefully shutting down server '%s'...", s.cfg.Name)
+	err := s.httpServer.Shutdown(ctx)
+	if err == nil {
+		s.running = false
+	}
+	return err
+}
+
+// Addr returns the network address the server is listening on.
+func (s *serverInstance) Addr() string {
+	return s.httpServer.Addr
+}

pkg/server/manager_test.go

@@ -0,0 +1,125 @@
+package server
+
+import (
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"testing"
+	"time"
+
+	"github.com/bitechdev/ResolveSpec/pkg/logger"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// getFreePort asks the kernel for a free open port that is ready to use.
+func getFreePort(t *testing.T) int {
+	t.Helper()
+	addr, err := net.ResolveTCPAddr("tcp", "localhost:0")
+	require.NoError(t, err)
+
+	l, err := net.ListenTCP("tcp", addr)
+	require.NoError(t, err)
+	defer l.Close()
+	return l.Addr().(*net.TCPAddr).Port
+}
+
+func TestServerManagerLifecycle(t *testing.T) {
+	// Initialize logger for test output
+	logger.Init(true)
+
+	// Create a new server manager
+	sm := NewManager()
+
+	// Define a simple test handler
+	testHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte("Hello, World!"))
+	})
+
+	// Get a free port for the server to listen on to avoid conflicts
+	testPort := getFreePort(t)
+
+	// Add a new server configuration
+	serverConfig := Config{
+		Name:    "TestServer",
+		Host:    "localhost",
+		Port:    testPort,
+		Handler: testHandler,
+	}
+	instance, err := sm.Add(serverConfig)
+	require.NoError(t, err, "should be able to add a new server")
+	require.NotNil(t, instance, "added instance should not be nil")
+
+	// --- Test StartAll ---
+	err = sm.StartAll()
+	require.NoError(t, err, "StartAll should not return an error")
+
+	// Give the server a moment to start up
+	time.Sleep(100 * time.Millisecond)
+
+	// --- Verify Server is Running ---
+	client := &http.Client{Timeout: 2 * time.Second}
+	url := fmt.Sprintf("http://localhost:%d", testPort)
+	resp, err := client.Get(url)
+	require.NoError(t, err, "should be able to make a request to the running server")
+
+	assert.Equal(t, http.StatusOK, resp.StatusCode, "expected status OK from the test server")
+	body, err := io.ReadAll(resp.Body)
+	require.NoError(t, err)
+	resp.Body.Close()
+	assert.Equal(t, "Hello, World!", string(body), "response body should match expected value")
+
+	// --- Test Get ---
+	retrievedInstance, err := sm.Get("TestServer")
+	require.NoError(t, err, "should be able to get server by name")
+	assert.Equal(t, instance.Addr(), retrievedInstance.Addr(), "retrieved instance should be the same")
+
+	// --- Test List ---
+	instanceList := sm.List()
+	require.Len(t, instanceList, 1, "list should contain one instance")
+	assert.Equal(t, instance.Addr(), instanceList[0].Addr(), "listed instance should be the same")
+
+	// --- Test StopAll ---
+	err = sm.StopAll()
+	require.NoError(t, err, "StopAll should not return an error")
+
+	// Give the server a moment to shut down
+	time.Sleep(100 * time.Millisecond)
+
+	// --- Verify Server is Stopped ---
+	_, err = client.Get(url)
+	require.Error(t, err, "should not be able to make a request to a stopped server")
+
+	// --- Test Remove ---
+	err = sm.Remove("TestServer")
+	require.NoError(t, err, "should be able to remove a server")
+
+	_, err = sm.Get("TestServer")
+	require.Error(t, err, "should not be able to get a removed server")
+}
+
+func TestManagerErrorCases(t *testing.T) {
+	logger.Init(true)
+	sm := NewManager()
+	testPort := getFreePort(t)
+
+	// --- Test Add Duplicate Name ---
+	config1 := Config{Name: "Duplicate", Host: "localhost", Port: testPort, Handler: http.NewServeMux()}
+	_, err := sm.Add(config1)
+	require.NoError(t, err)
+
+	config2 := Config{Name: "Duplicate", Host: "localhost", Port: getFreePort(t), Handler: http.NewServeMux()}
+	_, err = sm.Add(config2)
+	require.Error(t, err, "should not be able to add a server with a duplicate name")
+
+	// --- Test Get Non-existent ---
+	_, err = sm.Get("NonExistent")
+	require.Error(t, err, "should get an error for a non-existent server")
+
+	// --- Test Add with Nil Handler ---
+	config3 := Config{Name: "NilHandler", Host: "localhost", Port: getFreePort(t), Handler: nil}
+	_, err = sm.Add(config3)
+	require.Error(t, err, "should not be able to add a server with a nil handler")
+}