diff --git a/dev/bots/test/prepare_package_test.dart b/dev/bots/test/prepare_package_test.dart
new file mode 100644
index 0000000..0d7a3a9
--- /dev/null
+++ b/dev/bots/test/prepare_package_test.dart
@@ -0,0 +1,193 @@
+// Copyright 2017 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:convert';
+import 'dart:io';
+
+import 'package:mockito/mockito.dart';
+import 'package:test/test.dart';
+import 'package:path/path.dart' as path;
+
+import '../prepare_package.dart';
+
+void main() {
+  group('ArchiveCreator', () {
+    ArchiveCreator preparer;
+    Directory tmpDir;
+    Directory flutterDir;
+    File outputFile;
+    MockProcessRunner runner;
+    List<MockProcessResult> results;
+    final List<List<String>> args = <List<String>>[];
+    final List<Map<Symbol, dynamic>> namedArgs = <Map<Symbol, dynamic>>[];
+    final String zipExe = Platform.isWindows ? 'zip.exe' : 'zip';
+    final String tarExe = Platform.isWindows ? 'tar.exe' : 'tar';
+    final String gitExe = Platform.isWindows ? 'git.bat' : 'git';
+    String flutterExe;
+
+    void _verifyCommand(List<dynamic> args, String expected) {
+      final List<String> expectedList = expected.split(' ');
+      final String executable = expectedList.removeAt(0);
+      expect(args[0], executable);
+      expect(args[1], orderedEquals(expectedList));
+    }
+
+    ProcessResult _nextResult(Invocation invocation) {
+      args.add(invocation.positionalArguments);
+      namedArgs.add(invocation.namedArguments);
+      return results.isEmpty ? new MockProcessResult('', '', 0) : results.removeAt(0);
+    }
+
+    void _answerWithResults() {
+      when(
+        runner.call(
+          typed(captureAny),
+          typed(captureAny),
+          environment: typed(captureAny, named: 'environment'),
+          workingDirectory: typed(captureAny, named: 'workingDirectory'),
+          includeParentEnvironment: typed(captureAny, named: 'includeParentEnvironment'),
+        ),
+      ).thenAnswer(_nextResult);
+    }
+
+    setUp(() async {
+      runner = new MockProcessRunner();
+      args.clear();
+      namedArgs.clear();
+      tmpDir = await Directory.systemTemp.createTemp('flutter_');
+      flutterDir = new Directory(path.join(tmpDir.path, 'flutter'));
+      flutterExe =
+          path.join(flutterDir.path, 'bin', Platform.isWindows ? 'flutter.bat' : 'flutter');
+    });
+
+    tearDown(() async {
+      await tmpDir.delete(recursive: true);
+    });
+
+    test('sets PUB_CACHE properly', () async {
+      outputFile = new File(path.join(tmpDir.absolute.path, 'flutter_master.tar.bz2'));
+      preparer = new ArchiveCreator(tmpDir, outputFile, runner: runner);
+      _answerWithResults();
+      results = <MockProcessResult>[new MockProcessResult('deadbeef\n', '', 0)];
+      preparer.checkoutFlutter('master');
+      preparer.prepareArchive();
+      preparer.createArchive();
+      expect(
+        verify(runner.call(
+          captureAny,
+          captureAny,
+          workingDirectory: captureAny,
+          environment: captureAny,
+          includeParentEnvironment: typed(captureAny, named: 'includeParentEnvironment'),
+        )).captured[2]['PUB_CACHE'],
+        endsWith(path.join('flutter', '.pub-cache')),
+      );
+    });
+
+    test('calls the right commands for tar output', () async {
+      outputFile = new File(path.join(tmpDir.absolute.path, 'flutter_master.tar.bz2'));
+      preparer = new ArchiveCreator(tmpDir, outputFile, runner: runner);
+      _answerWithResults();
+      results = <MockProcessResult>[new MockProcessResult('deadbeef\n', '', 0)];
+      preparer.checkoutFlutter('master');
+      preparer.prepareArchive();
+      preparer.createArchive();
+      final List<String> commands = <String>[
+        '$gitExe clone -b master https://chromium.googlesource.com/external/github.com/flutter/flutter',
+        '$gitExe reset --hard master',
+        '$gitExe remote remove origin',
+        '$gitExe remote add origin https://github.com/flutter/flutter.git',
+        '$flutterExe doctor',
+        '$flutterExe update-packages',
+        '$flutterExe precache',
+        '$flutterExe ide-config',
+        '$flutterExe create --template=app ${path.join(tmpDir.path, 'create_app')}',
+        '$flutterExe create --template=package ${path.join(tmpDir.path, 'create_package')}',
+        '$flutterExe create --template=plugin ${path.join(tmpDir.path, 'create_plugin')}',
+        '$gitExe clean -f -X **/.packages',
+        '$tarExe cjf ${path.join(tmpDir.path, 'flutter_master.tar.bz2')} flutter',
+      ];
+      int step = 0;
+      for (String command in commands) {
+        _verifyCommand(args[step++], command);
+      }
+    });
+
+    test('calls the right commands for zip output', () async {
+      outputFile = new File(path.join(tmpDir.absolute.path, 'flutter_master.zip'));
+      preparer = new ArchiveCreator(tmpDir, outputFile, runner: runner);
+      _answerWithResults();
+      results = <MockProcessResult>[new MockProcessResult('deadbeef\n', '', 0)];
+      preparer.checkoutFlutter('master');
+      preparer.prepareArchive();
+      preparer.createArchive();
+      final List<String> commands = <String>[
+        '$gitExe clone -b master https://chromium.googlesource.com/external/github.com/flutter/flutter',
+        '$gitExe reset --hard master',
+        '$gitExe remote remove origin',
+        '$gitExe remote add origin https://github.com/flutter/flutter.git',
+        '$flutterExe doctor',
+        '$flutterExe update-packages',
+        '$flutterExe precache',
+        '$flutterExe ide-config',
+        '$flutterExe create --template=app ${path.join(tmpDir.path, 'create_app')}',
+        '$flutterExe create --template=package ${path.join(tmpDir.path, 'create_package')}',
+        '$flutterExe create --template=plugin ${path.join(tmpDir.path, 'create_plugin')}',
+        '$gitExe clean -f -X **/.packages',
+        '$zipExe -r -9 -q ${path.join(tmpDir.path, 'flutter_master.zip')} flutter',
+      ];
+      int step = 0;
+      for (String command in commands) {
+        _verifyCommand(args[step++], command);
+      }
+    });
+
+    test('throws when a command errors out', () async {
+      outputFile = new File(path.join(tmpDir.absolute.path, 'flutter.tar.bz2'));
+      preparer = new ArchiveCreator(
+        tmpDir,
+        outputFile,
+        runner: runner,
+      );
+
+      results = <MockProcessResult>[
+        new MockProcessResult('', '', 0),
+        new MockProcessResult('OMG! OMG! an ERROR!\n', '', -1)
+      ];
+      _answerWithResults();
+      expect(() => preparer.checkoutFlutter('master'),
+          throwsA(const isInstanceOf<ProcessFailedException>()));
+      expect(args.length, 2);
+      _verifyCommand(args[0],
+          '$gitExe clone -b master https://chromium.googlesource.com/external/github.com/flutter/flutter');
+      _verifyCommand(args[1], '$gitExe reset --hard master');
+    });
+  });
+}
+
+class MockProcessRunner extends Mock implements Function {
+  ProcessResult call(
+    String executable,
+    List<String> arguments, {
+    String workingDirectory,
+    Map<String, String> environment,
+    bool includeParentEnvironment,
+    bool runInShell,
+    Encoding stdoutEncoding,
+    Encoding stderrEncoding,
+  });
+}
+
+class MockProcessResult extends Mock implements ProcessResult {
+  MockProcessResult(this.stdout, [this.stderr = '', this.exitCode = 0]);
+
+  @override
+  dynamic stdout = '';
+
+  @override
+  dynamic stderr;
+
+  @override
+  int exitCode;
+}