add functions/vendor files

vendor/github.com/dghubble/go-twitter/twitter/backoffs_test.go

@@ -0,0 +1,37 @@
+package twitter
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNewExponentialBackOff(t *testing.T) {
+	b := newExponentialBackOff()
+	assert.Equal(t, 5*time.Second, b.InitialInterval)
+	assert.Equal(t, 2.0, b.Multiplier)
+	assert.Equal(t, 320*time.Second, b.MaxInterval)
+}
+
+func TestNewAggressiveExponentialBackOff(t *testing.T) {
+	b := newAggressiveExponentialBackOff()
+	assert.Equal(t, 1*time.Minute, b.InitialInterval)
+	assert.Equal(t, 2.0, b.Multiplier)
+	assert.Equal(t, 16*time.Minute, b.MaxInterval)
+}
+
+// BackoffRecorder is an implementation of backoff.BackOff that records
+// calls to NextBackOff and Reset for later inspection in tests.
+type BackOffRecorder struct {
+	Count int
+}
+
+func (b *BackOffRecorder) NextBackOff() time.Duration {
+	b.Count++
+	return 1 * time.Nanosecond
+}
+
+func (b *BackOffRecorder) Reset() {
+	b.Count = 0
+}