tests for some things that came up as regressions when building out examples.

chart.go

@@ -373,12 +373,20 @@ func (c Chart) getAnnotationAdjustedCanvasBox(r Renderer, canvasBox Box, xr, yr,
 	return canvasBox.OuterConstrain(c.Box(), annotationSeriesBox)
 }
 
+func (c Chart) getBackgroundStyle() Style {
+	return c.Background.WithDefaultsFrom(c.styleDefaultsBackground())
+}
+
 func (c Chart) drawBackground(r Renderer) {
-	DrawBox(r, c.Box(), c.Background.WithDefaultsFrom(c.styleDefaultsBackground()))
+	DrawBox(r, c.Box(), c.getBackgroundStyle())
+}
+
+func (c Chart) getCanvasStyle() Style {
+	return c.Canvas.WithDefaultsFrom(c.styleDefaultsCanvas())
 }
 
 func (c Chart) drawCanvas(r Renderer, canvasBox Box) {
-	DrawBox(r, canvasBox, c.Canvas.WithDefaultsFrom(c.styleDefaultsCanvas()))
+	DrawBox(r, canvasBox, c.getCanvasStyle())
 }
 
 func (c Chart) drawAxes(r Renderer, canvasBox Box, xrange, yrange, yrangeAlt Range, xticks, yticks, yticksAlt []Tick) {

chart_test.go

@@ -7,6 +7,7 @@ import (
 	"time"
 
 	"github.com/blendlabs/go-assert"
+	"github.com/wcharczuk/go-chart/drawing"
 )
 
 func TestChartGetDPI(t *testing.T) {
@@ -123,6 +124,96 @@ func TestChartGetRanges(t *testing.T) {
 	assert.Equal(19.7, yra2.Max)
 }
 
+func TestChartGetRangesUseTicks(t *testing.T) {
+	assert := assert.New(t)
+
+	// this test asserts that ticks should supercede manual ranges when generating the overall ranges.
+
+	c := Chart{
+		YAxis: YAxis{
+			Ticks: []Tick{
+				{0.0, "Zero"},
+				{1.0, "1.0"},
+				{2.0, "2.0"},
+				{3.0, "3.0"},
+				{4.0, "4.0"},
+				{5.0, "Five"},
+			},
+			Range: Range{
+				Min: -5.0,
+				Max: 5.0,
+			},
+		},
+		Series: []Series{
+			ContinuousSeries{
+				XValues: []float64{-2.0, -1.0, 0, 1.0, 2.0},
+				YValues: []float64{1.0, 2.0, 3.0, 4.0, 4.5},
+			},
+		},
+	}
+
+	xr, yr, yar := c.getRanges()
+	assert.Equal(-2.0, xr.Min)
+	assert.Equal(2.0, xr.Max)
+	assert.Equal(0.0, yr.Min)
+	assert.Equal(5.0, yr.Max)
+	assert.True(yar.IsZero(), yar.String())
+}
+
+func TestChartGetRangesUseUserRanges(t *testing.T) {
+	assert := assert.New(t)
+
+	// this test asserts that ticks should supercede manual ranges when generating the overall ranges.
+
+	c := Chart{
+		YAxis: YAxis{
+			Range: Range{
+				Min: -5.0,
+				Max: 5.0,
+			},
+		},
+		Series: []Series{
+			ContinuousSeries{
+				XValues: []float64{-2.0, -1.0, 0, 1.0, 2.0},
+				YValues: []float64{1.0, 2.0, 3.0, 4.0, 4.5},
+			},
+		},
+	}
+
+	xr, yr, yar := c.getRanges()
+	assert.Equal(-2.0, xr.Min)
+	assert.Equal(2.0, xr.Max)
+	assert.Equal(-5.0, yr.Min)
+	assert.Equal(5.0, yr.Max)
+	assert.True(yar.IsZero(), yar.String())
+}
+
+func TestChartGetBackgroundStyle(t *testing.T) {
+	assert := assert.New(t)
+
+	c := Chart{
+		Background: Style{
+			FillColor: drawing.ColorBlack,
+		},
+	}
+
+	bs := c.getBackgroundStyle()
+	assert.Equal(bs.FillColor.String(), drawing.ColorBlack.String())
+}
+
+func TestChartGetCanvasStyle(t *testing.T) {
+	assert := assert.New(t)
+
+	c := Chart{
+		Canvas: Style{
+			FillColor: drawing.ColorBlack,
+		},
+	}
+
+	bs := c.getCanvasStyle()
+	assert.Equal(bs.FillColor.String(), drawing.ColorBlack.String())
+}
+
 func TestChartGetDefaultCanvasBox(t *testing.T) {
 	assert := assert.New(t)
 

range.go

@@ -14,7 +14,9 @@ type Range struct {
 
 // IsZero returns if the range has been set or not.
 func (r Range) IsZero() bool {
-	return r.Min == 0 && r.Max == 0 && r.Domain == 0
+	return (r.Min == 0 || math.IsNaN(r.Min)) &&
+		(r.Max == 0 || math.IsNaN(r.Max)) &&
+		r.Domain == 0
 }
 
 // Delta returns the difference between the min and max value.