Support test 0.12.15.

pubspec.yaml

 name: scheduled_test
-version: 0.12.5+6
+version: 0.12.6
 author: Dart Team <misc@dartlang.org>
 description: >
   A package for writing readable tests of asynchronous behavior.
 
   This package works by building up a queue of asynchronous tasks called a
   "schedule", then executing those tasks in order. This allows the tests to
   read like synchronous, linear code, despite executing asynchronously.
 
 homepage: https://github.com/dart-lang/scheduled_test
 environment:
   sdk: '>=1.16.0 <2.0.0'
 dependencies:
   async: '^1.10.0'
   collection: '^1.5.0'
   http_multi_server: '>=1.0.0 <3.0.0'
   http: '>=0.9.0 <0.12.0'
   path: '>=0.9.0 <2.0.0'
   shelf: '>=0.5.2 <0.8.0'
   stack_trace: '>=0.9.1 <2.0.0'
 
   # Because scheduled_test exports test, it needs to keep its version constraint
   # tight to ensure that a constraint on scheduled_test properly constraints all
   # features it provides.
-  test: '>=0.12.7 <0.12.15'
+  test: '>=0.12.15 <0.12.16'
 dev_dependencies:
   metatest: "^0.2.1"
   shelf_web_socket: "^0.2.0"