From d1d2186a2fc6b35d9799d9efa7ce0b2604b35e1d Mon Sep 17 00:00:00 2001
From: Thomas Friedel <tomee6@gmail.com>
Date: Tue, 16 Apr 2019 16:39:53 +0200
Subject: [PATCH] added a function to run the tests on the software backend

---
 canvas_test.go | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)

diff --git a/canvas_test.go b/canvas_test.go
index f0e3c5f..e6a41fa 100644
--- a/canvas_test.go
+++ b/canvas_test.go
@@ -3,6 +3,7 @@ package canvas_test
 import (
 	"fmt"
 	"image"
+	_ "image/jpeg"
 	"image/png"
 	"math"
 	"os"
@@ -12,6 +13,7 @@ import (
 
 	"github.com/go-gl/gl/v3.2-core/gl"
 	"github.com/tfriedel6/canvas"
+	"github.com/tfriedel6/canvas/backend/software"
 	"github.com/tfriedel6/canvas/sdlcanvas"
 )
 
@@ -90,6 +92,74 @@ func run(t *testing.T, fn func(cv *canvas.Canvas)) {
 	}
 }
 
+func runsw(t *testing.T, fn func(cv *canvas.Canvas)) {
+	backend := softwarebackend.New(100, 100)
+	cv := canvas.New(backend)
+
+	cv.SetFillStyle("#000")
+	cv.FillRect(0, 0, 100, 100)
+	fn(cv)
+	img := cv.GetImageData(0, 0, 100, 100)
+
+	caller, _, _, ok := runtime.Caller(1)
+	if !ok {
+		t.Fatal("Failed to get caller")
+	}
+
+	callerFunc := runtime.FuncForPC(caller)
+	if callerFunc == nil {
+		t.Fatal("Failed to get caller function")
+	}
+
+	const prefix = "canvas_test.Test"
+	callerFuncName := callerFunc.Name()
+	callerFuncName = callerFuncName[strings.Index(callerFuncName, prefix)+len(prefix):]
+
+	fileName := fmt.Sprintf("testdata/%s.png", callerFuncName)
+
+	_, err := os.Stat(fileName)
+	if err != nil && !os.IsNotExist(err) {
+		t.Fatalf("Failed to stat file \"%s\": %v", fileName, err)
+	}
+
+	if os.IsNotExist(err) {
+		err = writeImage(img, fileName)
+		if err != nil {
+			t.Fatal(err)
+		}
+		return
+	}
+
+	f, err := os.Open(fileName)
+	if err != nil {
+		t.Fatalf("Failed to open file \"%s\": %v", fileName, err)
+	}
+	defer f.Close()
+
+	refImg, err := png.Decode(f)
+	if err != nil {
+		t.Fatalf("Failed to decode file \"%s\": %v", fileName, err)
+	}
+
+	if b := img.Bounds(); b.Min.X != 0 || b.Min.Y != 0 || b.Max.X != 100 || b.Max.Y != 100 {
+		t.Fatalf("Image bounds must be 0,0,100,100")
+	}
+	if b := refImg.Bounds(); b.Min.X != 0 || b.Min.Y != 0 || b.Max.X != 100 || b.Max.Y != 100 {
+		t.Fatalf("Image bounds must be 0,0,100,100")
+	}
+
+	for y := 0; y < 100; y++ {
+		for x := 0; x < 100; x++ {
+			r1, g1, b1, a1 := img.At(x, y).RGBA()
+			r2, g2, b2, a2 := refImg.At(x, y).RGBA()
+			if r1 != r2 || g1 != g2 || b1 != b2 || a1 != a2 {
+				writeImage(img, fmt.Sprintf("testdata/%s_fail.png", callerFuncName))
+				t.FailNow()
+			}
+		}
+	}
+}
+
 func writeImage(img *image.RGBA, fileName string) error {
 	f, err := os.OpenFile(fileName, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0777)
 	if err != nil {