more test coverage

.gitignore

@@ -1,3 +1,3 @@
 *.zpl
-*.png
+cmd/zplgfa/*.png
 cmd/zplgfa/zplgfa

README.md

@@ -4,6 +4,7 @@
 [![Go Report Card](https://goreportcard.com/badge/github.com/SimonWaldherr/zplgfa)](https://goreportcard.com/report/github.com/SimonWaldherr/zplgfa) 
 [![codebeat badge](https://codebeat.co/badges/28d795af-6f9b-453a-94c2-4fafb8b5b0d5)](https://codebeat.co/projects/github-com-simonwaldherr-zplgfa-master) 
 [![BCH compliance](https://bettercodehub.com/edge/badge/SimonWaldherr/zplgfa?branch=master)](https://bettercodehub.com/results/SimonWaldherr/zplgfa) 
+[![FOSSA Status](https://app.fossa.io/api/projects/git%2Bgithub.com%2FSimonWaldherr%2Fzplgfa.svg?type=shield)](https://app.fossa.io/projects/git%2Bgithub.com%2FSimonWaldherr%2Fzplgfa?ref=badge_shield) 
 [![license](https://img.shields.io/badge/license-MIT-blue.svg)](https://raw.githubusercontent.com/SimonWaldherr/zplgfa/master/LICENSE) 
 
 The ZPLGFA Golang package implements some functions to convert PNG, JPEG and GIF files to ZPL compatible ^GF-elements ([Graphic Fields](https://www.zebra.com/us/en/support-downloads/knowledge-articles/gf-graphic-field-zpl-command.html)).

zplgfa_test.go

@@ -1,7 +1,14 @@
 package zplgfa
 
 import (
+	"image"
+	_ "image/gif"
+	_ "image/jpeg"
+	_ "image/png"
+	"log"
+	"os"
 	"testing"
+	"strings"
 )
 
 func Test_CompressASCII(t *testing.T) {
@@ -9,3 +16,44 @@ func Test_CompressASCII(t *testing.T) {
 		t.Fatalf("CompressASCII failed")
 	}
 }
+
+func Test_ConvertToZPL(t *testing.T) {
+	// open file
+	file, err := os.Open("./test.png")
+	if err != nil {
+		log.Printf("Warning: could not open the file: %s\n", err)
+		return
+	}
+
+	defer file.Close()
+
+	// load image head information
+	config, format, err := image.DecodeConfig(file)
+	if err != nil {
+		log.Printf("Warning: image not compatible, format: %s, config: %v, error: %s\n", format, config, err)
+	}
+
+	// reset file pointer to the beginning of the file
+	file.Seek(0, 0)
+
+	// load and decode image
+	img, _, err := image.Decode(file)
+	if err != nil {
+		log.Printf("Warning: could not decode the file, %s\n", err)
+		return
+	}
+
+	// flatten image
+	flat := FlattenImage(img)
+
+	// convert image to zpl compatible type
+	gfimg := ConvertToZPL(flat, CompressedASCII)
+	
+	// remove whitespace - only for the test
+	gfimg = strings.Replace(gfimg, " ", "", -1)
+	gfimg = strings.Replace(gfimg, "\n", "", -1)
+
+	if gfimg != "^XA,^FS^FO0,0^GFA,32,51,3,,::01C000::,001C00::,1DDC00::,::^FS,^XZ" {
+		t.Fatalf("ConvertToZPL failed")
+	}
+}