Added unit test for waitingCache

pkg/storage/modules/waiting_cache_test.go

@@ -0,0 +1,52 @@
+package modules
+
+import (
+	"crypto/rand"
+	"testing"
+	"time"
+
+	"github.com/loopholelabs/silo/pkg/storage/sources"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestWaitingCache(t *testing.T) {
+
+	// Create a new block storage, backed by memory storage
+	size := 1024 * 1024 * 32
+	mem := sources.NewMemoryStorage(size)
+	metrics := NewMetrics(mem)
+	waiting := NewWaitingCache(metrics, 4096)
+
+	data := make([]byte, 12000)
+	rand.Read(data)
+
+	// We'll write something in 50ms
+	go func() {
+		time.Sleep(50 * time.Millisecond)
+		_, err := waiting.WriteAt(data, 0)
+		assert.NoError(t, err)
+	}()
+
+	// The waiting cache will wait for data to be available.
+	offset := int64(20)
+	buffer := make([]byte, 8000)
+	ctime := time.Now()
+	_, err := waiting.ReadAt(buffer, offset)
+	assert.NoError(t, err)
+	wait_time := time.Since(ctime).Milliseconds()
+
+	// We'd expect this read to take around 50ms (It's waiting for the data)
+	assert.InDelta(t, wait_time, 50, 10)
+
+	assert.Equal(t, data[offset:int(offset)+len(buffer)], buffer)
+
+	// Read again
+	ctime2 := time.Now()
+	_, err = waiting.ReadAt(buffer, offset)
+	assert.NoError(t, err)
+	wait_time2 := time.Since(ctime2).Milliseconds()
+
+	// We'd expect this read to be instant (The data exists now)
+	assert.InDelta(t, wait_time2, 0, 10)
+
+}