Add fail-fast on init for missing provider credentials

internal/observability/middleware_response_writer_test.go

@@ -0,0 +1,65 @@
+package observability
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+var _ http.Flusher = (*metricsResponseWriter)(nil)
+var _ http.Flusher = (*statusResponseWriter)(nil)
+
+type testFlusherRecorder struct {
+	*httptest.ResponseRecorder
+	flushCount int
+}
+
+func newTestFlusherRecorder() *testFlusherRecorder {
+	return &testFlusherRecorder{ResponseRecorder: httptest.NewRecorder()}
+}
+
+func (r *testFlusherRecorder) Flush() {
+	r.flushCount++
+}
+
+func TestMetricsResponseWriterWriteHeaderOnlyOnce(t *testing.T) {
+	rec := httptest.NewRecorder()
+	rw := &metricsResponseWriter{ResponseWriter: rec, statusCode: http.StatusOK}
+
+	rw.WriteHeader(http.StatusAccepted)
+	rw.WriteHeader(http.StatusInternalServerError)
+
+	assert.Equal(t, http.StatusAccepted, rec.Code)
+	assert.Equal(t, http.StatusAccepted, rw.statusCode)
+}
+
+func TestMetricsResponseWriterFlushDelegates(t *testing.T) {
+	rec := newTestFlusherRecorder()
+	rw := &metricsResponseWriter{ResponseWriter: rec, statusCode: http.StatusOK}
+
+	rw.Flush()
+
+	assert.Equal(t, 1, rec.flushCount)
+}
+
+func TestStatusResponseWriterWriteHeaderOnlyOnce(t *testing.T) {
+	rec := httptest.NewRecorder()
+	rw := &statusResponseWriter{ResponseWriter: rec, statusCode: http.StatusOK}
+
+	rw.WriteHeader(http.StatusNoContent)
+	rw.WriteHeader(http.StatusInternalServerError)
+
+	assert.Equal(t, http.StatusNoContent, rec.Code)
+	assert.Equal(t, http.StatusNoContent, rw.statusCode)
+}
+
+func TestStatusResponseWriterFlushDelegates(t *testing.T) {
+	rec := newTestFlusherRecorder()
+	rw := &statusResponseWriter{ResponseWriter: rec, statusCode: http.StatusOK}
+
+	rw.Flush()
+
+	assert.Equal(t, 1, rec.flushCount)
+}