From a756db412b434256e66991d7cc639197ea1dd58d Mon Sep 17 00:00:00 2001
From: Will Charczuk <will.charczuk@gmail.com>
Date: Thu, 14 Jul 2016 12:30:57 -0700
Subject: [PATCH] adding tests.

---
 moving_average_series_test.go | 53 +++++++++++++++++++++++++++++++++++
 util.go                       | 11 ++++++--
 util_test.go                  | 17 +++++++++++
 3 files changed, 79 insertions(+), 2 deletions(-)
 create mode 100644 moving_average_series_test.go

diff --git a/moving_average_series_test.go b/moving_average_series_test.go
new file mode 100644
index 0000000..ec49caf
--- /dev/null
+++ b/moving_average_series_test.go
@@ -0,0 +1,53 @@
+package chart
+
+import (
+	"testing"
+
+	"github.com/blendlabs/go-assert"
+)
+
+type mockValueProvider struct {
+	X []float64
+	Y []float64
+}
+
+func (m mockValueProvider) Len() int {
+	return MinInt(len(m.X), len(m.Y))
+}
+
+func (m mockValueProvider) GetValue(index int) (x, y float64) {
+	x = m.X[index]
+	y = m.Y[index]
+	return
+}
+
+func TestMovingAverageSeriesGetValue(t *testing.T) {
+	assert := assert.New(t)
+
+	mockSeries := mockValueProvider{
+		Seq(1.0, 10.0),
+		Seq(10, 1.0),
+	}
+	assert.Equal(10, mockSeries.Len())
+
+	mas := &MovingAverageSeries{
+		InnerSeries: mockSeries,
+		WindowSize:  10,
+	}
+
+	var yvalues []float64
+	for x := 0; x < mas.Len(); x++ {
+		_, y := mas.GetValue(x)
+		yvalues = append(yvalues, y)
+	}
+
+	assert.Equal(10.0, yvalues[0])
+	assert.Equal(9.5, yvalues[1])
+	assert.Equal(9.0, yvalues[2])
+	assert.Equal(8.5, yvalues[3])
+	assert.Equal(8.0, yvalues[4])
+	assert.Equal(7.5, yvalues[5])
+	assert.Equal(7.0, yvalues[6])
+	assert.Equal(6.5, yvalues[7])
+	assert.Equal(6.0, yvalues[8])
+}
diff --git a/util.go b/util.go
index 15e02fe..ac440f8 100644
--- a/util.go
+++ b/util.go
@@ -130,8 +130,15 @@ func Seq(start, end float64, steps ...float64) []float64 {
 	if len(steps) > 0 {
 		step = steps[0]
 	}
-	for x := start; x <= end; x += step {
-		values = append(values, x)
+
+	if start < end {
+		for x := start; x <= end; x += step {
+			values = append(values, x)
+		}
+	} else {
+		for x := start; x >= end; x = x - step {
+			values = append(values, x)
+		}
 	}
 	return values
 }
diff --git a/util_test.go b/util_test.go
index d81c8be..aff684e 100644
--- a/util_test.go
+++ b/util_test.go
@@ -83,3 +83,20 @@ func TestGetRoundToForDelta(t *testing.T) {
 	assert.Equal(10.0, GetRoundToForDelta(101.00))
 	assert.Equal(1.0, GetRoundToForDelta(11.00))
 }
+
+func TestSeq(t *testing.T) {
+	assert := assert.New(t)
+
+	asc := Seq(1.0, 10.0)
+	assert.Len(asc, 10)
+
+	desc := Seq(10.0, 1.0)
+	assert.Len(desc, 10)
+}
+
+func TestPercentDifference(t *testing.T) {
+	assert := assert.New(t)
+
+	assert.Equal(0.5, PercentDifference(1.0, 1.5))
+	assert.Equal(-0.5, PercentDifference(2.0, 1.0))
+}