can just supply inverted ranges.

tick_test.go

@@ -1,12 +1,57 @@
 package chart
 
-/*
-func TestGenerateTicksWithStep(t *testing.T) {
+import (
+	"testing"
+
+	assert "github.com/blendlabs/go-assert"
+)
+
+func TestGenerateContinuousTicks(t *testing.T) {
 	assert := assert.New(t)
 
+	f, err := GetDefaultFont()
+	assert.Nil(err)
 
+	r, err := PNG(1024, 1024)
+	assert.Nil(err)
+	r.SetFont(f)
 
-	ticks := GenerateContinuousTicksWithStep(&ContinuousRange{Min: 1.0, Max: 10.0, Domain: 100}, 1.0, FloatValueFormatter, false)
-	assert.Len(ticks, 10)
+	ra := &ContinuousRange{
+		Min:    0.0,
+		Max:    10.0,
+		Domain: 256,
+	}
+
+	vf := FloatValueFormatter
+
+	ticks := GenerateContinuousTicks(r, ra, false, Style{}, vf)
+	assert.NotEmpty(ticks)
+	assert.Len(ticks, 11)
+	assert.Equal(0.0, ticks[0].Value)
+	assert.Equal(10, ticks[len(ticks)-1].Value)
+}
+
+func TestGenerateContinuousTicksDescending(t *testing.T) {
+	assert := assert.New(t)
+
+	f, err := GetDefaultFont()
+	assert.Nil(err)
+
+	r, err := PNG(1024, 1024)
+	assert.Nil(err)
+	r.SetFont(f)
+
+	ra := &ContinuousRange{
+		Min:    10.0,
+		Max:    0.0,
+		Domain: 256,
+	}
+
+	vf := FloatValueFormatter
+
+	ticks := GenerateContinuousTicks(r, ra, false, Style{}, vf)
+	assert.NotEmpty(ticks)
+	assert.Len(ticks, 11)
+	assert.Equal(10.0, ticks[0].Value)
+	assert.Equal(0.0, ticks[len(ticks)-1].Value)
 }
-*/