Add fail-fast on init for missing provider credentials

cmd/gateway/main_test.go

@@ -0,0 +1,57 @@
+package main
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+var _ http.Flusher = (*responseWriter)(nil)
+
+type countingFlusherRecorder struct {
+	*httptest.ResponseRecorder
+	flushCount int
+}
+
+func newCountingFlusherRecorder() *countingFlusherRecorder {
+	return &countingFlusherRecorder{ResponseRecorder: httptest.NewRecorder()}
+}
+
+func (r *countingFlusherRecorder) Flush() {
+	r.flushCount++
+}
+
+func TestResponseWriterWriteHeaderOnlyOnce(t *testing.T) {
+	rec := httptest.NewRecorder()
+	rw := &responseWriter{ResponseWriter: rec, statusCode: http.StatusOK}
+
+	rw.WriteHeader(http.StatusCreated)
+	rw.WriteHeader(http.StatusInternalServerError)
+
+	assert.Equal(t, http.StatusCreated, rec.Code)
+	assert.Equal(t, http.StatusCreated, rw.statusCode)
+}
+
+func TestResponseWriterWriteSetsImplicitStatus(t *testing.T) {
+	rec := httptest.NewRecorder()
+	rw := &responseWriter{ResponseWriter: rec, statusCode: http.StatusOK}
+
+	n, err := rw.Write([]byte("ok"))
+
+	assert.NoError(t, err)
+	assert.Equal(t, 2, n)
+	assert.Equal(t, http.StatusOK, rec.Code)
+	assert.Equal(t, http.StatusOK, rw.statusCode)
+	assert.Equal(t, 2, rw.bytesWritten)
+}
+
+func TestResponseWriterFlushDelegates(t *testing.T) {
+	rec := newCountingFlusherRecorder()
+	rw := &responseWriter{ResponseWriter: rec, statusCode: http.StatusOK}
+
+	rw.Flush()
+
+	assert.Equal(t, 1, rec.flushCount)
+}