Use YAML as the format for the pubspec file.

utils/tests/pub/pub_tests.dart

Index: utils/tests/pub/pub_tests.dart
diff --git a/utils/tests/pub/pub_tests.dart b/utils/tests/pub/pub_tests.dart
index 91e95d4d4a4bd33aeeb0b69826a8e59f8ba6952a..210a8b379fa1c695820423a3e6c4391a6df537c1 100644
--- a/utils/tests/pub/pub_tests.dart
+++ b/utils/tests/pub/pub_tests.dart
@@ -70,7 +70,7 @@ updateCommand() {
       ])
     ],
     app: dir('myapp', [
-      file('pubspec', 'foo')
+      file('pubspec', '- foo')

[Bob Nystrom, 2012/04/25 22:59:01]

Now that we have a real format, I would put the dependencies under a
dependencies key like:

dependencies:
- foo
- bar

(I may have the YAML wrong here.)

[nweiz, 2012/04/25 23:05:14]

Done.

     ]),
     args: ['update'],
     expectedPackageDir: [
@@ -84,14 +84,14 @@ updateCommand() {
     cache: [
       dir('foo', [
         file('foo.dart', 'main() => "foo";'),
-        file('pubspec', 'bar')
+        file('pubspec', '- bar')
       ]),
       dir('bar', [
         file('bar.dart', 'main() => "bar";'),
       ])
     ],
     app: dir('myapp', [
-      file('pubspec', 'foo')
+      file('pubspec', '- foo')
     ]),
     args: ['update'],
     expectedPackageDir: [