fix tests due to doesNotComplete matcher in package:test

pkgs/json_rpc_2/pubspec.yaml

diff --git a/pkgs/json_rpc_2/pubspec.yaml b/pkgs/json_rpc_2/pubspec.yaml
index 57a1e37..e1a2a92 100644
--- a/pkgs/json_rpc_2/pubspec.yaml
+++ b/pkgs/json_rpc_2/pubspec.yaml
@@ -7,6 +7,6 @@
   stack_trace: '>=0.9.1 <2.0.0'
   stream_channel: '^1.1.0'
 dev_dependencies:
-  test: ">=0.12.0 <0.13.0"
+  test: "^0.12.21"
 environment:
   sdk: ">=1.8.0 <2.0.0"

pkgs/json_rpc_2/test/server/utils.dart

diff --git a/pkgs/json_rpc_2/test/server/utils.dart b/pkgs/json_rpc_2/test/server/utils.dart
index f33cb13..02d9f34 100644
--- a/pkgs/json_rpc_2/test/server/utils.dart
+++ b/pkgs/json_rpc_2/test/server/utils.dart
@@ -61,20 +61,6 @@
   })));
 }
 
-/// Returns a matcher that matches [Future]s that never complete.
-Matcher get doesNotComplete => predicate((future) {
-  future.then(expectAsync((_) {
-    // This will never be called. [expectAsync] with `count: 0` ensures that an
-    // error will be thrown when [future] completes.
-  }, count: 0));
-
-  // Make sure there's enough time in the test for [expectAsync] to fail if it's
-  // going to.
-  expect(pumpEventQueue(), completes);
-
-  return true;
-});
-
 /// Returns a matcher that matches a [json_rpc.RpcException] with an
 /// `invalid_params` error code.
 Matcher throwsInvalidParams(String message) {