Resolves sixel rendering regression issue and adds gui unit test to validate rendered image (#221)

* Reset line feed mode on sixel handling

* Sixel test

main_test.go

@@ -24,8 +24,12 @@ func terminate(msg string) int {
 	return 1
 }
 
-func sleep() {
-	time.Sleep(time.Second)
+func sleep(seconds ...int) {
+	count := 1
+	if len(seconds) > 0 {
+		count = seconds[0]
+	}
+	time.Sleep(time.Duration(count) * time.Second)
 }
 
 func hash(path string) string {
@@ -162,6 +166,30 @@ func TestScreenFeatures(t *testing.T) {
 	})
 }
 
+func TestSixel(t *testing.T) {
+	runMain(func() {
+
+                testFunc := func(term *terminal.Terminal, g *gui.GUI) {
+                        termRef = term; guiRef = g
+
+                        sleep()
+                        send(term, "export PS1='> '\n")
+                        sleep()
+                        send(term, "clear\n")
+                        sleep()
+                        send(term, "cat example.sixel\n")
+                        sleep(4)
+
+                        guiRef.Screenshot("test-sixel.png")
+                        validateScreen("test-sixel.png")
+
+                        g.Close()
+                }
+
+                initialize(testFunc)
+        })
+}
+
 // Last Test should terminate main goroutine since it's infinity looped to execute others GUI tests in main goroutine
 func TestExit(t *testing.T) {
 	os.Exit(0)

terminal/sixel.go

@@ -125,6 +125,12 @@ func sixelHandler(pty chan rune, terminal *Terminal) error {
 		return fmt.Errorf("Failed to parse sixel data: %s", err)
 	}
 
+	isNewLineMode := terminal.terminalState.IsNewLineMode()
+	if isNewLineMode == false {
+		terminal.SetNewLineMode()
+		defer terminal.SetLineFeedMode()
+	}
+
 	drawSixel(six, terminal)
 
 	return nil