test: add comprehensive tests for all Epic 1 stories

Story 1.2: Database Layer
- Test database client creation, connection, ping, and close
- Test connection pooling configuration
- Tests skip if database is not available (short mode)

Story 1.3: Health Monitoring and Metrics
- Test health registry registration and checking
- Test database health checker
- Test liveness and readiness checks
- Test metrics creation, middleware, and handler
- Test Prometheus metrics endpoint

Story 1.4: Error Handling and Error Bus
- Test channel-based error bus creation
- Test error publishing with context
- Test nil error handling
- Test channel full scenario
- Test graceful shutdown
- Fix Close() method to handle multiple calls safely

Story 1.5: HTTP Server and Middleware
- Test server creation with all middleware
- Test request ID middleware
- Test logging middleware
- Test panic recovery middleware
- Test CORS middleware
- Test timeout middleware
- Test health and metrics endpoints
- Test server shutdown

Story 1.6: OpenTelemetry Tracing
- Test tracer initialization (enabled/disabled)
- Test development and production modes
- Test OTLP exporter configuration
- Test graceful shutdown
- Test no-op tracer provider

All tests follow Go testing best practices:
- Table-driven tests where appropriate
- Parallel execution
- Proper mocking of interfaces
- Skip tests requiring external dependencies in short mode

internal/errorbus/channel_bus.go

@@ -12,11 +12,12 @@ import (
 
 // ChannelBus implements a channel-based error bus.
 type ChannelBus struct {
-	errors chan errorWithContext
-	logger logger.Logger
-	done   chan struct{}
-	wg     sync.WaitGroup
-	once   sync.Once
+	errors    chan errorWithContext
+	logger    logger.Logger
+	done      chan struct{}
+	wg        sync.WaitGroup
+	once      sync.Once
+	closeOnce sync.Once
 }
 
 type errorWithContext struct {
@@ -157,7 +158,9 @@ func (b *ChannelBus) Close() error {
 		close(b.done)
 	})
 	b.wg.Wait()
-	close(b.errors)
+	b.closeOnce.Do(func() {
+		close(b.errors)
+	})
 	return nil
 }
 

internal/errorbus/channel_bus_test.go

@@ -0,0 +1,199 @@
+package errorbus
+
+import (
+	"context"
+	"errors"
+	"testing"
+	"time"
+
+	"git.dcentral.systems/toolz/goplt/pkg/logger"
+)
+
+func TestNewChannelBus(t *testing.T) {
+	t.Parallel()
+
+	mockLogger := &mockLogger{}
+	bus := NewChannelBus(mockLogger, 100)
+
+	if bus == nil {
+		t.Fatal("Expected bus, got nil")
+	}
+
+	if bus.errors == nil {
+		t.Error("Expected errors channel, got nil")
+	}
+
+	if bus.logger == nil {
+		t.Error("Expected logger, got nil")
+	}
+
+	// Clean up
+	_ = bus.Close()
+}
+
+func TestNewChannelBus_DefaultBufferSize(t *testing.T) {
+	t.Parallel()
+
+	mockLogger := &mockLogger{}
+	bus := NewChannelBus(mockLogger, 0)
+
+	if bus == nil {
+		t.Fatal("Expected bus, got nil")
+	}
+
+	// Clean up
+	_ = bus.Close()
+}
+
+func TestChannelBus_Publish(t *testing.T) {
+	t.Parallel()
+
+	mockLogger := &mockLogger{}
+	bus := NewChannelBus(mockLogger, 10)
+
+	testErr := errors.New("test error")
+	ctx := context.Background()
+
+	// Publish error
+	bus.Publish(ctx, testErr)
+
+	// Wait a bit for the error to be processed
+	time.Sleep(100 * time.Millisecond)
+
+	// Verify error was logged
+	if len(mockLogger.errors) == 0 {
+		t.Error("Expected error to be logged")
+	}
+
+	// Clean up
+	_ = bus.Close()
+}
+
+func TestChannelBus_Publish_NilError(t *testing.T) {
+	t.Parallel()
+
+	mockLogger := &mockLogger{}
+	bus := NewChannelBus(mockLogger, 10)
+
+	ctx := context.Background()
+
+	// Publish nil error (should be ignored)
+	bus.Publish(ctx, nil)
+
+	// Wait a bit
+	time.Sleep(50 * time.Millisecond)
+
+	// Verify nil error was not logged
+	if len(mockLogger.errors) > 0 {
+		t.Error("Expected nil error to be ignored")
+	}
+
+	// Clean up
+	_ = bus.Close()
+}
+
+func TestChannelBus_Publish_WithContext(t *testing.T) {
+	t.Parallel()
+
+	mockLogger := &mockLogger{}
+	bus := NewChannelBus(mockLogger, 10)
+
+	testErr := errors.New("test error")
+	ctx := context.WithValue(context.Background(), "request_id", "test-request-id")
+
+	bus.Publish(ctx, testErr)
+
+	// Wait for processing
+	time.Sleep(100 * time.Millisecond)
+
+	// Verify error was logged with context
+	if len(mockLogger.errors) == 0 {
+		t.Error("Expected error to be logged")
+	}
+
+	// Clean up
+	_ = bus.Close()
+}
+
+func TestChannelBus_Close(t *testing.T) {
+	t.Parallel()
+
+	mockLogger := &mockLogger{}
+	bus := NewChannelBus(mockLogger, 10)
+
+	// Publish some errors
+	for i := 0; i < 5; i++ {
+		bus.Publish(context.Background(), errors.New("test error"))
+	}
+
+	// Close and wait
+	if err := bus.Close(); err != nil {
+		t.Errorf("Close failed: %v", err)
+	}
+
+	// Verify channel is closed
+	select {
+	case <-bus.errors:
+		// Channel is closed, this is expected
+	default:
+		t.Error("Expected errors channel to be closed")
+	}
+}
+
+func TestChannelBus_Close_MultipleTimes(t *testing.T) {
+	t.Parallel()
+
+	mockLogger := &mockLogger{}
+	bus := NewChannelBus(mockLogger, 10)
+
+	// Close first time
+	if err := bus.Close(); err != nil {
+		t.Errorf("First Close failed: %v", err)
+	}
+
+	// Close second time should be safe (uses sync.Once)
+	// The channel is already closed, but Close() should handle this gracefully
+	if err := bus.Close(); err != nil {
+		t.Errorf("Second Close failed: %v", err)
+	}
+}
+
+func TestChannelBus_ChannelFull(t *testing.T) {
+	t.Parallel()
+
+	mockLogger := &mockLogger{}
+	// Use small buffer to test channel full scenario
+	bus := NewChannelBus(mockLogger, 1)
+
+	// Fill the channel
+	bus.Publish(context.Background(), errors.New("error1"))
+
+	// This should not block (channel is full, should log directly)
+	bus.Publish(context.Background(), errors.New("error2"))
+
+	// Wait a bit
+	time.Sleep(100 * time.Millisecond)
+
+	// Clean up
+	_ = bus.Close()
+}
+
+// mockLogger implements logger.Logger for testing.
+type mockLogger struct {
+	errors []string
+}
+
+func (m *mockLogger) Debug(msg string, fields ...logger.Field) {}
+func (m *mockLogger) Info(msg string, fields ...logger.Field)  {}
+func (m *mockLogger) Warn(msg string, fields ...logger.Field)  {}
+func (m *mockLogger) Error(msg string, fields ...logger.Field) {
+	m.errors = append(m.errors, msg)
+}
+
+func (m *mockLogger) With(fields ...logger.Field) logger.Logger {
+	return m
+}
+
+func (m *mockLogger) WithContext(ctx context.Context) logger.Logger {
+	return m
+}