adds percent change series

percent_change_series_test.go

@@ -0,0 +1,35 @@
+package chart
+
+import (
+	"testing"
+
+	"github.com/blend/go-sdk/assert"
+)
+
+func TestPercentageDifferenceSeries(t *testing.T) {
+	assert := assert.New(t)
+
+	cs := ContinuousSeries{
+		XValues: LinearRange(1.0, 10.0),
+		YValues: LinearRange(1.0, 10.0),
+	}
+
+	pcs := PercentChangeSeries{
+		Name:        "Test Series",
+		InnerSeries: cs,
+	}
+
+	assert.Equal("Test Series", pcs.GetName())
+	assert.Equal(10, pcs.Len())
+	x0, y0 := pcs.GetValues(0)
+	assert.Equal(1.0, x0)
+	assert.Equal(0, y0)
+
+	xn, yn := pcs.GetValues(9)
+	assert.Equal(10.0, xn)
+	assert.Equal(9.0, yn)
+
+	xn, yn = pcs.GetLastValues()
+	assert.Equal(10.0, xn)
+	assert.Equal(9.0, yn)
+}