feat: edge gateway service

gateway/internal/testutil/observability.go

@@ -0,0 +1,94 @@
+package testutil
+
+import (
+	"bytes"
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"sync"
+	"testing"
+	"time"
+
+	"galaxy/gateway/internal/logging"
+	"galaxy/gateway/internal/telemetry"
+
+	"github.com/stretchr/testify/require"
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+)
+
+// LogBuffer is a concurrency-safe in-memory buffer used by observability
+// tests.
+type LogBuffer struct {
+	mu  sync.Mutex
+	buf bytes.Buffer
+}
+
+// Write appends p to the buffer.
+func (b *LogBuffer) Write(p []byte) (int, error) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	return b.buf.Write(p)
+}
+
+// String returns the current buffer contents.
+func (b *LogBuffer) String() string {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	return b.buf.String()
+}
+
+// NewObservedLogger constructs a JSON zap logger that writes into an in-memory
+// buffer suitable for log assertions.
+func NewObservedLogger(t *testing.T) (*zap.Logger, *LogBuffer) {
+	t.Helper()
+
+	buffer := &LogBuffer{}
+	encoderConfig := zap.NewProductionEncoderConfig()
+	encoderConfig.TimeKey = "timestamp"
+	encoderConfig.EncodeTime = zapcore.ISO8601TimeEncoder
+
+	core := zapcore.NewCore(
+		zapcore.NewJSONEncoder(encoderConfig),
+		zapcore.Lock(zapcore.AddSync(buffer)),
+		zap.DebugLevel,
+	)
+
+	logger := zap.New(core)
+	t.Cleanup(func() {
+		require.NoError(t, logging.Sync(logger))
+	})
+
+	return logger, buffer
+}
+
+// NewTelemetryRuntime constructs a telemetry runtime for tests and shuts it
+// down automatically.
+func NewTelemetryRuntime(t *testing.T, logger *zap.Logger) *telemetry.Runtime {
+	t.Helper()
+
+	runtime, err := telemetry.New(context.Background(), logger)
+	require.NoError(t, err)
+
+	t.Cleanup(func() {
+		ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+		defer cancel()
+		require.NoError(t, runtime.Shutdown(ctx))
+	})
+
+	return runtime
+}
+
+// ScrapeMetrics returns the Prometheus exposition produced by handler.
+func ScrapeMetrics(t *testing.T, handler http.Handler) string {
+	t.Helper()
+
+	req := httptest.NewRequest(http.MethodGet, "/metrics", nil)
+	recorder := httptest.NewRecorder()
+	handler.ServeHTTP(recorder, req)
+	require.Equal(t, http.StatusOK, recorder.Code)
+
+	return recorder.Body.String()
+}