package main

import (
	"image/color"
	"testing"
)

// The built-in back arrow must leave the label band (bottom third) untouched
// and actually draw something above it.
func TestBackArrowLayout(t *testing.T) {
	img := backArrow(96, 96, color.White)
	lit := 0
	for y := 0; y < 64; y++ {
		for x := 0; x < 96; x++ {
			if r, _, _, _ := img.At(x, y).RGBA(); r > 0 {
				lit++
			}
		}
	}
	if lit < 200 {
		t.Errorf("arrow region has only %d lit pixels", lit)
	}
	for y := 72; y < 96; y++ {
		for x := 0; x < 96; x++ {
			if r, _, _, _ := img.At(x, y).RGBA(); r > 0 {
				t.Fatalf("label band pixel (%d,%d) is lit", x, y)
			}
		}
	}
}