First pass at "pub update" implementation.

utils/tests/pub/test_pub.dart

Index: utils/tests/pub/test_pub.dart
diff --git a/utils/tests/pub/test_pub.dart b/utils/tests/pub/test_pub.dart
index 49b64e88f2767c3d310bce94271b9395a5014107..73dbd111f1e6932f38891d8218c71840612e03d8 100644
--- a/utils/tests/pub/test_pub.dart
+++ b/utils/tests/pub/test_pub.dart
@@ -28,10 +28,12 @@ FileDescriptor file(String name, String contents) =>
 DirectoryDescriptor dir(String name, [List<Descriptor> contents]) =>
     new DirectoryDescriptor(name, contents);
 
-void testPub(String description, [List<Descriptor> cache, List<String> args,
+void testPub(String description, [List<Descriptor> cache, Descriptor app,
+    List<String> args, List<Descriptor> expectedPackageDir,
     String output, int exitCode = 0]) {
   asyncTest(description, 1, () {
     var createdSandboxDir;
+    var createdAppDir;
 
     deleteSandboxIfCreated() {
       if (createdSandboxDir != null) {
@@ -45,18 +47,22 @@ void testPub(String description, [List<Descriptor> cache, List<String> args,
 
     final future = _setUpSandbox().chain((sandboxDir) {
       createdSandboxDir = sandboxDir;
-      return _setUpCache(sandboxDir, cache);
+      return _setUpApp(sandboxDir, app);
+    }).chain((appDir) {
+      createdAppDir = appDir;
+      return _setUpCache(createdSandboxDir, cache);
     }).chain((cacheDir) {
+      var workingDir;
+      if (createdAppDir != null) workingDir = createdAppDir.path;
+
       if (cacheDir != null) {
         // TODO(rnystrom): Hack in the cache directory path. Should pass this
         // in using environment var once #752 is done.
-        args.add('--cachedir=${cacheDir.path}');
+        args.add('--cachedir=${getFullPath(cacheDir)}');
       }
 
-      return _runPub(args);
-    });
-
-    future.then((result) {
+      return _runPub(args, workingDir);
+    }).chain((result) {
       _validateOutput(output, result.stdout);
 
       Expect.equals(result.stderr.length, 0,
@@ -66,6 +72,11 @@ void testPub(String description, [List<Descriptor> cache, List<String> args,
       Expect.equals(result.exitCode, exitCode,
           'Pub returned exit code ${result.exitCode}, expected $exitCode.');
 
+      return _validateExpectedPackages(createdAppDir, expectedPackageDir);
+    });
+
+    future.then((valid) {
+      Expect.isTrue(valid); // TODO(bob): Report which expectation failed.
       deleteSandboxIfCreated();
     });
 
@@ -86,7 +97,14 @@ Future _setUpCache(Directory sandboxDir, List<Descriptor> cache) {
   return dir('pub-cache', cache).create(sandboxDir);
 }
 
-Future<ProcessResult> _runPub(List<String> pubArgs) {
+Future _setUpApp(Directory sandboxDir, Descriptor app) {
+  // No app directory.
+  if (app == null) return new Future.immediate(null);
+
+  return app.create(sandboxDir);
+}
+
+Future<ProcessResult> _runPub(List<String> pubArgs, String workingDir) {
   // Find a dart executable we can use to run pub. Uses the one that the
   // test infrastructure uses.
   final scriptDir = new File(new Options().script).directorySync().path;
@@ -99,7 +117,15 @@ Future<ProcessResult> _runPub(List<String> pubArgs) {
   final args = [pubPath];
   args.addAll(pubArgs);
 
-  return runProcess(dartBin, args);
+  return runProcess(dartBin, args, workingDir);
+}
+
+Future<bool> _validateExpectedPackages(Directory appDir,
+    List<Descriptor> expectedPackageDir) {
+  // No expectation.
+  if (expectedPackageDir == null) return new Future.immediate(true);
+
+  return dir('packages', expectedPackageDir).validate(appDir.path);
 }
 
 /**
@@ -110,6 +136,11 @@ Future<ProcessResult> _runPub(List<String> pubArgs) {
 void _validateOutput(String expectedText, List<String> actual) {
   final expected = expectedText.split('\n');
 
+  // Strip off the last line. This lets us have expected multiline strings
+  // where the closing ''' is on its own line. It also fixes '' expected output
+  // to expect zero lines of output, not a single empty line.
+  expected.removeLast();
+
   final length = Math.min(expected.length, actual.length);
   for (var i = 0; i < length; i++) {
     if (expected[i].trim() != actual[i].trim()) {
@@ -159,6 +190,13 @@ class Descriptor {
    * completed after the creation is done.
    */
   abstract Future create(String dir);
+
+  /**
+   * Validates that this descriptor correctly matches the actual file system
+   * entry at [path]. Returns a [Future] that completes when the validation is
+   * done.
+   */
+  abstract Future<bool> validate(String path);
 }
 
 /**
@@ -181,6 +219,18 @@ class FileDescriptor extends Descriptor {
   Future<File> create(String dir) {
     return writeTextFile(join(dir, name), contents);
   }
+
+  /**
+   * Validates that this file correctly matches the actual file at [path].
+   */
+  Future<bool> validate(String path) {
+    path = join(path, name);
+    return fileExists(path).chain((exists) {
+      if (!exists) return new Future.immediate(false);
+
+      return readTextFile(path).transform((text) => text == contents);
+    });
+  }
 }
 
 /**
@@ -219,4 +269,21 @@ class DirectoryDescriptor extends Descriptor {
 
     return completer.future;
   }
+
+  /**
+   * Validates that the directory at [path] contains all of the expected
+   * contents in this descriptor. Note that this does *not* check that the
+   * directory doesn't contain other unexpected stuff, just that it *does*
+   * contain the stuff we do expect.
+   */
+  Future<bool> validate(String path) {
+    // Validate each of the items in this directory.
+    final entryFutures = contents.map(
+        (entry) => entry.validate(join(path, name)));
+
+    // If they are all valid, the directory is valid.
+    return Futures.wait(entryFutures).transform((entries) {
+      return !entries.some((valid) => !valid);
+    });
+  }
 }