Refactor Raspberry Pi GPIO and add GPIO mock

tests/pkg/gpio/gpio_mock_test.dart

+// Copyright (c) 2015, the Fletch project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE.md file.
+
+import 'package:expect/expect.dart';
+import 'package:gpio/gpio.dart';
+import 'package:gpio/gpio_mock.dart';
+
+main() {
+  test1();
+  test2();
+  test3();
+}
+
+void test1() {
+  var gpio = new MockGPIO();
+  Expect.equals(GPIO.defaultPins, gpio.pins);
+  for (int i = 0; i < gpio.pins; i++) {
+    Expect.isFalse(gpio.getPin(i));
+    gpio.setPin(i, true);
+    Expect.isTrue(gpio.getPin(i));
+  }
+}
+
+void test2() {
+  void checkRange(gpio, pins) {
+    bool isRangeError(e) => e is RangeError;
+    Expect.throws(() => gpio.getPin(-1), isRangeError);
+    Expect.throws(() => gpio.getPin(pins + 1), isRangeError);
+    Expect.throws(() => gpio.setPin(-1, true), isRangeError);
+    Expect.throws(() => gpio.setPin(pins + 1, true), isRangeError);
+    Expect.throws(() => gpio.getMode(-1), isRangeError);
+    Expect.throws(() => gpio.getMode(pins + 1), isRangeError);
+    Expect.throws(() => gpio.setMode(-1, Mode.output), isRangeError);
+    Expect.throws(() => gpio.setMode(pins + 1, Mode.output), isRangeError);
+  }
+  checkRange(new MockGPIO(), GPIO.defaultPins);
+  checkRange(new MockGPIO(1), 1);
+  checkRange(new MockGPIO(2), 2);
+}
+
+void test3() {
+  int getCount = 0;
+  int setCount = 0;
+
+  bool getPin(int pin) {
+    getCount++;
+    if (getCount == 1) {
+      throw new _MyException();
+    } else {
+      return true;
+    }
+  }
+
+  void setPin(int pin, bool value) {
+    setCount++;
+    if (setCount == 1) {
+      throw new _MyException();
+    }
+  }
+
+  var gpio = new MockGPIO();
+  gpio.registerGetPin(getPin);
+  gpio.registerSetPin(setPin);
+  Expect.throws(() => gpio.getPin(1), (e) => e is _MyException);
+  Expect.throws(() => gpio.setPin(1, false), (e) => e is _MyException);
+  Expect.isTrue(gpio.getPin(1));
+  gpio.setPin(1, false);
+  Expect.equals(2, getCount);
+  Expect.equals(2, setCount);
+}
+
+class _MyException implements Exception {}