handle android n in the android sdk

packages/flutter_tools/lib/src/android/android_sdk.dart

@@ -11,16 +11,22 @@ import '../base/os.dart';
 import '../globals.dart';
 
 // Android SDK layout:
-//
+
 // $ANDROID_HOME/platform-tools/adb
+
 // $ANDROID_HOME/build-tools/19.1.0/aapt, dx, zipalign
 // $ANDROID_HOME/build-tools/22.0.1/aapt
 // $ANDROID_HOME/build-tools/23.0.2/aapt
+// $ANDROID_HOME/build-tools/24.0.0-preview/aapt
+
 // $ANDROID_HOME/platforms/android-22/android.jar
 // $ANDROID_HOME/platforms/android-23/android.jar
+// $ANDROID_HOME/platforms/android-N/android.jar
 
-// TODO(devoncarew): We need a way to locate the Android SDK w/o using an environment variable.
-// Perhaps something like `flutter config --android-home=foo/bar`.
+// Special case some version names in the sdk.
+const Map<String, int> _namedVersionMap = const <String, int> {
+  'android-N': 24
+};
 
 /// Locate ADB. Prefer to use one from an Android SDK, if we can locate that.
 String getAdbPath([AndroidSdk existingSdk]) {
@@ -47,8 +53,6 @@ class AndroidSdk {
   AndroidSdkVersion _latestVersion;
 
   static AndroidSdk locateAndroidSdk() {
-    // TODO: Use explicit configuration information from a metadata file?
-
     String androidHomeDir;
     if (Platform.environment.containsKey('ANDROID_HOME')) {
       androidHomeDir = Platform.environment['ANDROID_HOME'];
@@ -130,11 +134,11 @@ class AndroidSdk {
         .toList();
     }
 
-    List<Version> buildToolsVersions = <Version>[]; // 19.1.0, 22.0.1, ...
+    List<Version> buildTools = <Version>[]; // 19.1.0, 22.0.1, ...
 
     Directory buildToolsDir = new Directory(path.join(directory, 'build-tools'));
     if (buildToolsDir.existsSync()) {
-      buildToolsVersions = buildToolsDir
+      buildTools = buildToolsDir
         .listSync()
         .map((FileSystemEntity entity) {
           try {
@@ -149,25 +153,32 @@ class AndroidSdk {
 
     // Here we match up platforms with cooresponding build-tools. If we don't
     // have a match, we don't return anything for that platform version. So if
-    // the user only have 'android-22' and 'build-tools/19.0.0', we don't find
+    // the user only has 'android-22' and 'build-tools/19.0.0', we don't find
     // an Android sdk.
-    _sdkVersions = platforms.map((String platform) {
-      int sdkVersion;
+    _sdkVersions = platforms.map((String platformName) {
+      int platformVersion;
 
       try {
-        sdkVersion = int.parse(platform.substring('android-'.length));
+        if (_namedVersionMap.containsKey(platformName))
+          platformVersion = _namedVersionMap[platformName];
+        else
+          platformVersion = int.parse(platformName.substring('android-'.length));
       } catch (error) {
         return null;
       }
 
-      Version buildToolsVersion = Version.primary(buildToolsVersions.where((Version version) {
-        return version.major == sdkVersion;
+      Version buildToolsVersion = Version.primary(buildTools.where((Version version) {
+        return version.major == platformVersion;
       }).toList());
 
       if (buildToolsVersion == null)
         return null;
 
-      return new AndroidSdkVersion(this, platform, buildToolsVersion.toString());
+      return new AndroidSdkVersion(
+        this,
+        platformVersionName: platformName,
+        buildToolsVersionName: buildToolsVersion.toString()
+      );
     }).where((AndroidSdkVersion version) => version != null).toList();
 
     _sdkVersions.sort();
@@ -180,13 +191,21 @@ class AndroidSdk {
 }
 
 class AndroidSdkVersion implements Comparable<AndroidSdkVersion> {
-  AndroidSdkVersion(this.sdk, this.androidVersion, this.buildToolsVersion);
+  AndroidSdkVersion(this.sdk, {
+    this.platformVersionName,
+    this.buildToolsVersionName
+  });
 
   final AndroidSdk sdk;
-  final String androidVersion;
-  final String buildToolsVersion;
-
-  int get sdkLevel => int.parse(androidVersion.substring('android-'.length));
+  final String platformVersionName;
+  final String buildToolsVersionName;
+
+  int get sdkLevel {
+    if (_namedVersionMap.containsKey(platformVersionName))
+      return _namedVersionMap[platformVersionName];
+    else
+      return int.parse(platformVersionName.substring('android-'.length));
+  }
 
   String get androidJarPath => getPlatformsPath('android.jar');
 
@@ -205,20 +224,18 @@ class AndroidSdkVersion implements Comparable<AndroidSdkVersion> {
   }
 
   String getPlatformsPath(String itemName) {
-    return path.join(sdk.directory, 'platforms', androidVersion, itemName);
+    return path.join(sdk.directory, 'platforms', platformVersionName, itemName);
   }
 
   String getBuildToolsPath(String binaryName) {
-    return path.join(sdk.directory, 'build-tools', buildToolsVersion, binaryName);
+    return path.join(sdk.directory, 'build-tools', buildToolsVersionName, binaryName);
   }
 
   @override
-  int compareTo(AndroidSdkVersion other) {
-    return sdkLevel - other.sdkLevel;
-  }
+  int compareTo(AndroidSdkVersion other) => sdkLevel - other.sdkLevel;
 
   @override
-  String toString() => '[${sdk.directory}, SDK version $sdkLevel, build-tools $buildToolsVersion]';
+  String toString() => '[${sdk.directory}, SDK version $sdkLevel, build-tools $buildToolsVersionName]';
 
   bool _exists(String path, { bool complain: false }) {
     if (!FileSystemEntity.isFileSync(path)) {

packages/flutter_tools/test/android_sdk_test.dart

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:io';
+
+import 'package:flutter_tools/src/android/android_sdk.dart';
+import 'package:path/path.dart' as path;
+import 'package:test/test.dart';
+
+import 'src/context.dart';
+
+void main() {
+  group('android_sdk AndroidSdk', () {
+    Directory sdkDir;
+
+    tearDown(() {
+      sdkDir?.deleteSync(recursive: true);
+    });
+
+    testUsingContext('parse sdk', () {
+      sdkDir = _createSdkDirectory();
+      AndroidSdk sdk = new AndroidSdk(sdkDir.path);
+
+      expect(sdk.latestVersion, isNotNull);
+      expect(sdk.latestVersion.sdkLevel, 23);
+    });
+
+    testUsingContext('parse sdk N', () {
+      sdkDir = _createSdkDirectory(withAndroidN: true);
+      AndroidSdk sdk = new AndroidSdk(sdkDir.path);
+
+      expect(sdk.latestVersion, isNotNull);
+      expect(sdk.latestVersion.sdkLevel, 24);
+    });
+  });
+
+  group('android_sdk AndroidSdkVersion', () {
+    testUsingContext('parse normal', () {
+      AndroidSdk sdk = new AndroidSdk('.');
+      AndroidSdkVersion ver = new AndroidSdkVersion(sdk,
+        platformVersionName: 'android-23', buildToolsVersionName: '23.0.0');
+      expect(ver.sdkLevel, 23);
+    });
+
+    testUsingContext('parse android n', () {
+      AndroidSdk sdk = new AndroidSdk('.');
+      AndroidSdkVersion ver = new AndroidSdkVersion(sdk,
+        platformVersionName: 'android-N', buildToolsVersionName: '24.0.0');
+      expect(ver.sdkLevel, 24);
+    });
+  });
+}
+
+Directory _createSdkDirectory({ bool withAndroidN: false }) {
+  Directory dir = Directory.systemTemp.createTempSync('android-sdk');
+
+  _createSdkFile(dir, 'platform-tools/adb');
+
+  _createSdkFile(dir, 'build-tools/19.1.0/aapt');
+  _createSdkFile(dir, 'build-tools/22.0.1/aapt');
+  _createSdkFile(dir, 'build-tools/23.0.2/aapt');
+  if (withAndroidN)
+    _createSdkFile(dir, 'build-tools/24.0.0-preview/aapt');
+
+  _createSdkFile(dir, 'platforms/android-22/android.jar');
+  _createSdkFile(dir, 'platforms/android-23/android.jar');
+  if (withAndroidN)
+    _createSdkFile(dir, 'platforms/android-N/android.jar');
+
+  return dir;
+}
+
+void _createSdkFile(Directory dir, String filePath) {
+  File file = new File(path.join(dir.path, filePath));
+  file.createSync(recursive: true);
+}