Add test to histogram-array

Author: bohde

histogram-array/main.go

@@ -8,6 +8,11 @@ import (
 	axiprotocol "github.com/ReconfigureIO/sdaccel/axi/protocol"
 )
 
+// calculate the bin for the histogram
+func CalculateIndex(sample uint32) uint16 {
+	return uint16(sample) >> (16 - 9)
+}
+
 // magic identifier for exporting
 func Top(
 	inputData uintptr,
@@ -32,11 +37,9 @@ func Top(
 	for ; length > 0; length-- {
 		// First we'll pull of each sample from the channel
 		sample := <-inputChan
-		// calculate the bin for the histogram
-		index := uint16(sample) >> (16 - 9)
 
 		// And increment the value in that bin
-		histogram[uint(index)] += 1
+		histogram[CalculateIndex(sample)] += 1
 	}
 
 	data := make(chan uint32)

histogram-array/main_test.go

@@ -0,0 +1,17 @@
+package main
+
+import (
+	"testing"
+	"testing/quick"
+)
+
+func TestCalculateIndexDoesNotOutOfBounds(t *testing.T) {
+	// Check that we never generate an index out of bounds
+	f := func(x uint32) bool {
+		index := CalculateIndex(x)
+		return index < 512
+	}
+	if err := quick.Check(f, nil); err != nil {
+		t.Error(err)
+	}
+}