diff --git a/pkgs/checks/test/extensions/core_test.dart b/pkgs/checks/test/extensions/core_test.dart
index ac5222e..47096b3 100644
--- a/pkgs/checks/test/extensions/core_test.dart
+++ b/pkgs/checks/test/extensions/core_test.dart
@@ -6,6 +6,8 @@
 import 'package:checks/context.dart';
 import 'package:test/scaffolding.dart';
 
+import '../test_shared.dart';
+
 void main() {
   group('TypeChecks', () {
     test('isA', () {
@@ -140,24 +142,3 @@
     });
   });
 }
-
-extension on Check<Iterable<String>?> {
-  // TODO: remove this once we have a deepEquals or equivalent
-  void toStringEquals(List<String>? other) {
-    final otherToString = other.toString();
-    context.expect(() => ['toString equals'], (actual) {
-      final actualToString = actual.toString();
-      return actual.toString() == otherToString
-          ? null
-          : Rejection(actual: actualToString);
-    });
-  }
-}
-
-extension on Check<Rejection?> {
-  void isARejection({List<String>? which, required String actual}) {
-    this.isNotNull()
-      ..has((p0) => p0.actual, 'actual').equals(actual)
-      ..has((p0) => p0.which, 'which').toStringEquals(which);
-  }
-}
diff --git a/pkgs/checks/test/test_shared.dart b/pkgs/checks/test/test_shared.dart
new file mode 100644
index 0000000..4ad7ef8
--- /dev/null
+++ b/pkgs/checks/test/test_shared.dart
@@ -0,0 +1,27 @@
+// Copyright (c) 2022, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:checks/checks.dart';
+import 'package:checks/context.dart';
+
+extension TestIterableCheck on Check<Iterable<String>?> {
+  // TODO: remove this once we have a deepEquals or equivalent
+  void toStringEquals(List<String>? other) {
+    final otherToString = other.toString();
+    context.expect(() => ['toString equals'], (actual) {
+      final actualToString = actual.toString();
+      return actual.toString() == otherToString
+          ? null
+          : Rejection(actual: actualToString);
+    });
+  }
+}
+
+extension RejectionCheck on Check<Rejection?> {
+  void isARejection({List<String>? which, required String actual}) {
+    this.isNotNull()
+      ..has((p0) => p0.actual, 'actual').equals(actual)
+      ..has((p0) => p0.which, 'which').toStringEquals(which);
+  }
+}