improve error output

src/connected.js

@@ -8,32 +8,11 @@ let ipcon;
 let connectedList = '';
 const data = [];
 
-function errorOutput(code) {
-	switch (code) {
-		case 11:
-			return 'ALREADY CONNECTED';
-		case 12:
-			return 'NOT CONNECTED';
-		case 13:
-			return 'CONNECT FAILED';
-		case 21:
-			return 'INVALID FUNCTION ID';
-		case 31:
-			return 'TIMEOUT';
-		case 41:
-			return 'INVALID PARAMETER';
-		case 42:
-			return 'FUNCTION NOT SUPPORTED';
-		default:
-			return 'UNKNOWN';
-	}
-}
-
 function tfinit(HOST, PORT) {
 	ipcon = new Tinkerforge.IPConnection();
 	ipcon.connect(HOST, PORT,
 		error => {
-			console.log('Error: ' + errorOutput(error));
+			console.error('Error: ' + require('./error.js').error(error));
 			process.exit(1);
 		}
 	);

src/error.js

@@ -0,0 +1,20 @@
+module.exports.error = function (code) {
+	switch (code) {
+		case 11:
+			return 'ALREADY CONNECTED';
+		case 12:
+			return 'NOT CONNECTED';
+		case 13:
+			return 'CONNECT FAILED';
+		case 21:
+			return 'INVALID FUNCTION ID';
+		case 31:
+			return 'TIMEOUT';
+		case 41:
+			return 'INVALID PARAMETER';
+		case 42:
+			return 'FUNCTION NOT SUPPORTED';
+		default:
+			return 'UNKNOWN';
+	}
+};

src/error.test.js

@@ -0,0 +1,34 @@
+import test from 'ava';
+
+const errorOutput = require('./error.js');
+
+test('Error Code 11', t => {
+	t.is(errorOutput.error(11), 'ALREADY CONNECTED');
+});
+
+test('Error Code 12', t => {
+	t.is(errorOutput.error(12), 'NOT CONNECTED');
+});
+
+test('Error Code 13', t => {
+	t.is(errorOutput.error(13), 'CONNECT FAILED');
+});
+
+test('Error Code 21', t => {
+	t.is(errorOutput.error(21), 'INVALID FUNCTION ID');
+});
+
+test('Error Code 31', t => {
+	t.is(errorOutput.error(31), 'TIMEOUT');
+});
+
+test('Error Code 41', t => {
+	t.is(errorOutput.error(41), 'INVALID PARAMETER');
+});
+
+test('Error Code 42', t => {
+	t.is(errorOutput.error(42), 'FUNCTION NOT SUPPORTED');
+});
+test('Unknown Error Code', t => {
+	t.is(errorOutput.error(123), 'UNKNOWN');
+});