diff --git a/tests/language/function_subtype/null.dart b/tests/language/function_subtype/null_test.dart
similarity index 100%
rename from tests/language/function_subtype/null.dart
rename to tests/language/function_subtype/null_test.dart
diff --git a/tests/language/identifier/known_prefix_error_test.dart b/tests/language/identifier/known_prefix_error_test.dart
index 06ec097..458f6e0 100644
--- a/tests/language/identifier/known_prefix_error_test.dart
+++ b/tests/language/identifier/known_prefix_error_test.dart
@@ -15,6 +15,10 @@
 import 'built_in_prefix_library_async.dart' as async;
 import 'built_in_prefix_library_await.dart' as await;
 import 'built_in_prefix_library_hide.dart' as hide;
+import 'built_in_prefix_library_library.dart' as library;
+//                                               ^^^^^^^
+// [analyzer] COMPILE_TIME_ERROR.BUILT_IN_IDENTIFIER_IN_DECLARATION
+// [cfe] Can't use 'library' as a name here.
 import 'built_in_prefix_library_of.dart' as of;
 import 'built_in_prefix_library_on.dart' as on;
 import 'built_in_prefix_library_show.dart' as show;
@@ -22,52 +26,44 @@
 import 'built_in_prefix_library_yield.dart' as yield;
 
 async<dynamic> _async = new async.A();
-// [error line 24, column 1, length 5]
+// [error line 28, column 1, length 5]
 // [analyzer] COMPILE_TIME_ERROR.NOT_A_TYPE
 // [cfe] 'async' isn't a type.
-// [error line 24, column 1]
 // [cfe] Expected 0 type arguments.
 await<dynamic> _await = new await.A();
-// [error line 30, column 1, length 5]
+// [error line 33, column 1, length 5]
 // [analyzer] COMPILE_TIME_ERROR.NOT_A_TYPE
 // [cfe] 'await' isn't a type.
-// [error line 30, column 1]
 // [cfe] Expected 0 type arguments.
 hide<dynamic> _hide = new hide.A();
-// [error line 36, column 1, length 4]
+// [error line 38, column 1, length 4]
 // [analyzer] COMPILE_TIME_ERROR.NOT_A_TYPE
 // [cfe] 'hide' isn't a type.
-// [error line 36, column 1]
 // [cfe] Expected 0 type arguments.
 of<dynamic> _of = new of.A();
-// [error line 42, column 1, length 2]
+// [error line 43, column 1, length 2]
 // [analyzer] COMPILE_TIME_ERROR.NOT_A_TYPE
 // [cfe] 'of' isn't a type.
-// [error line 42, column 1]
 // [cfe] Expected 0 type arguments.
 on<dynamic> _on = new on.A();
 // [error line 48, column 1, length 2]
 // [analyzer] COMPILE_TIME_ERROR.NOT_A_TYPE
 // [cfe] 'on' isn't a type.
-// [error line 48, column 1]
 // [cfe] Expected 0 type arguments.
 show<dynamic> _show = new show.A();
-// [error line 54, column 1, length 4]
+// [error line 53, column 1, length 4]
 // [analyzer] COMPILE_TIME_ERROR.NOT_A_TYPE
 // [cfe] 'show' isn't a type.
-// [error line 54, column 1]
 // [cfe] Expected 0 type arguments.
 sync<dynamic> _sync = new sync.A();
-// [error line 60, column 1, length 4]
+// [error line 58, column 1, length 4]
 // [analyzer] COMPILE_TIME_ERROR.NOT_A_TYPE
 // [cfe] 'sync' isn't a type.
-// [error line 60, column 1]
 // [cfe] Expected 0 type arguments.
 yield<dynamic> _yield = new yield.A();
-// [error line 66, column 1, length 5]
+// [error line 63, column 1, length 5]
 // [analyzer] COMPILE_TIME_ERROR.NOT_A_TYPE
 // [cfe] 'yield' isn't a type.
-// [error line 66, column 1]
 // [cfe] Expected 0 type arguments.
 
 async.B<async> _B_async = new async.B();
@@ -107,49 +103,41 @@
 //      ^^^^^
 // [analyzer] COMPILE_TIME_ERROR.NON_TYPE_AS_TYPE_ARGUMENT
 // [cfe] 'async' isn't a type.
-//      ^
 // [cfe] Expected 0 type arguments.
 await.B<await<dynamic>> _B2_await = new await.B();
 //      ^^^^^
 // [analyzer] COMPILE_TIME_ERROR.NON_TYPE_AS_TYPE_ARGUMENT
 // [cfe] 'await' isn't a type.
-//      ^
 // [cfe] Expected 0 type arguments.
 hide.B<hide<dynamic>> _B2_hide = new hide.B();
 //     ^^^^
 // [analyzer] COMPILE_TIME_ERROR.NON_TYPE_AS_TYPE_ARGUMENT
 // [cfe] 'hide' isn't a type.
-//     ^
 // [cfe] Expected 0 type arguments.
 of.B<of<dynamic>> _B2_of = new of.B();
 //   ^^
 // [analyzer] COMPILE_TIME_ERROR.NON_TYPE_AS_TYPE_ARGUMENT
 // [cfe] 'of' isn't a type.
-//   ^
 // [cfe] Expected 0 type arguments.
 on.B<on<dynamic>> _B2_on = new on.B();
 //   ^^
 // [analyzer] COMPILE_TIME_ERROR.NON_TYPE_AS_TYPE_ARGUMENT
 // [cfe] 'on' isn't a type.
-//   ^
 // [cfe] Expected 0 type arguments.
 show.B<show<dynamic>> _B2_show = new show.B();
 //     ^^^^
 // [analyzer] COMPILE_TIME_ERROR.NON_TYPE_AS_TYPE_ARGUMENT
 // [cfe] 'show' isn't a type.
-//     ^
 // [cfe] Expected 0 type arguments.
 sync.B<sync<dynamic>> _B2_sync = new sync.B();
 //     ^^^^
 // [analyzer] COMPILE_TIME_ERROR.NON_TYPE_AS_TYPE_ARGUMENT
 // [cfe] 'sync' isn't a type.
-//     ^
 // [cfe] Expected 0 type arguments.
 yield.B<yield<dynamic>> _B2_yield = new yield.B();
 //      ^^^^^
 // [analyzer] COMPILE_TIME_ERROR.NON_TYPE_AS_TYPE_ARGUMENT
 // [cfe] 'yield' isn't a type.
-//      ^
 // [cfe] Expected 0 type arguments.
 
 main() {
diff --git a/tests/language/library/library6.dart b/tests/language/library/library6_test.dart
similarity index 72%
rename from tests/language/library/library6.dart
rename to tests/language/library/library6_test.dart
index 7f4ab4b..9ae8940 100644
--- a/tests/language/library/library6.dart
+++ b/tests/language/library/library6_test.dart
@@ -2,12 +2,9 @@
 // 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.
 
-// This tests that it is a compile-time error to both import a library
+// This tests that it is not a compile-time error to both import a library
 // that defines a function type alias and to have a local definition for
 // another function type alias with the same name.
-// This name conflict is considered an error even if Fun is never referred to.
-
-library Library6NegativeTest.dart;
 
 import "library5a.dart"; // Defines function type alias Fun
 
diff --git a/tests/language/nonfunction_type_aliases/mixed/infer_aliased_factory_invocation_07_test.dart b/tests/language/nonfunction_type_aliases/mixed/infer_aliased_factory_invocation_07_test.dart
index 126ca63..6c6a7ca 100644
--- a/tests/language/nonfunction_type_aliases/mixed/infer_aliased_factory_invocation_07_test.dart
+++ b/tests/language/nonfunction_type_aliases/mixed/infer_aliased_factory_invocation_07_test.dart
@@ -5,7 +5,7 @@
 // Requirements=nnbd-weak
 
 
-import 'infer_aliased_factory_invocation_06_lib.dart';
+import 'infer_aliased_factory_invocation_07_lib.dart';
 
 Type typeOf<X>() => X;
 
diff --git a/tests/language/prefix/new_test.dart b/tests/language/prefix/new_test.dart
index 23c7834..4e13b18 100644
--- a/tests/language/prefix/new_test.dart
+++ b/tests/language/prefix/new_test.dart
@@ -5,7 +5,7 @@
 library PrefixTest;
 
 import "package:expect/expect.dart";
-import "test1.dart";
+import "new_test1.dart";
 
 main() {
   Expect.equals(Prefix.getSource(), Prefix.getImport() + 1);
diff --git a/tests/language/prefix/new_test1.dart b/tests/language/prefix/new_test1.dart
index 106de80..812c604 100644
--- a/tests/language/prefix/new_test1.dart
+++ b/tests/language/prefix/new_test1.dart
@@ -4,7 +4,7 @@
 
 library PrefixTest1;
 
-import "test2.dart" as test2;
+import "new_test2.dart" as test2;
 
 class Prefix {
   static const int foo = 43;
diff --git a/tests/language_2/function_subtype/null.dart b/tests/language_2/function_subtype/null_test.dart
similarity index 100%
rename from tests/language_2/function_subtype/null.dart
rename to tests/language_2/function_subtype/null_test.dart
diff --git a/tests/language_2/identifier/known_prefix_error_test.dart b/tests/language_2/identifier/known_prefix_error_test.dart
index 73a5e97..2cc7982 100644
--- a/tests/language_2/identifier/known_prefix_error_test.dart
+++ b/tests/language_2/identifier/known_prefix_error_test.dart
@@ -17,6 +17,10 @@
 import 'built_in_prefix_library_async.dart' as async;
 import 'built_in_prefix_library_await.dart' as await;
 import 'built_in_prefix_library_hide.dart' as hide;
+import 'built_in_prefix_library_library.dart' as library;
+//                                               ^^^^^^^
+// [analyzer] COMPILE_TIME_ERROR.BUILT_IN_IDENTIFIER_IN_DECLARATION
+// [cfe] Can't use 'library' as a name here.
 import 'built_in_prefix_library_of.dart' as of;
 import 'built_in_prefix_library_on.dart' as on;
 import 'built_in_prefix_library_show.dart' as show;
@@ -24,42 +28,42 @@
 import 'built_in_prefix_library_yield.dart' as yield;
 
 async<dynamic> _async = new async.A();
-// [error line 26, column 1, length 5]
+// [error line 30, column 1, length 5]
 // [analyzer] COMPILE_TIME_ERROR.NOT_A_TYPE
 // [cfe] 'async' isn't a type.
 // [cfe] Expected 0 type arguments.
 await<dynamic> _await = new await.A();
-// [error line 31, column 1, length 5]
+// [error line 35, column 1, length 5]
 // [analyzer] COMPILE_TIME_ERROR.NOT_A_TYPE
 // [cfe] 'await' isn't a type.
 // [cfe] Expected 0 type arguments.
 hide<dynamic> _hide = new hide.A();
-// [error line 36, column 1, length 4]
+// [error line 40, column 1, length 4]
 // [analyzer] COMPILE_TIME_ERROR.NOT_A_TYPE
 // [cfe] 'hide' isn't a type.
 // [cfe] Expected 0 type arguments.
 of<dynamic> _of = new of.A();
-// [error line 41, column 1, length 2]
+// [error line 45, column 1, length 2]
 // [analyzer] COMPILE_TIME_ERROR.NOT_A_TYPE
 // [cfe] 'of' isn't a type.
 // [cfe] Expected 0 type arguments.
 on<dynamic> _on = new on.A();
-// [error line 46, column 1, length 2]
+// [error line 50, column 1, length 2]
 // [analyzer] COMPILE_TIME_ERROR.NOT_A_TYPE
 // [cfe] 'on' isn't a type.
 // [cfe] Expected 0 type arguments.
 show<dynamic> _show = new show.A();
-// [error line 51, column 1, length 4]
+// [error line 55, column 1, length 4]
 // [analyzer] COMPILE_TIME_ERROR.NOT_A_TYPE
 // [cfe] 'show' isn't a type.
 // [cfe] Expected 0 type arguments.
 sync<dynamic> _sync = new sync.A();
-// [error line 56, column 1, length 4]
+// [error line 60, column 1, length 4]
 // [analyzer] COMPILE_TIME_ERROR.NOT_A_TYPE
 // [cfe] 'sync' isn't a type.
 // [cfe] Expected 0 type arguments.
 yield<dynamic> _yield = new yield.A();
-// [error line 61, column 1, length 5]
+// [error line 65, column 1, length 5]
 // [analyzer] COMPILE_TIME_ERROR.NOT_A_TYPE
 // [cfe] 'yield' isn't a type.
 // [cfe] Expected 0 type arguments.
diff --git a/tests/language_2/library/library6.dart b/tests/language_2/library/library6_test.dart
similarity index 73%
rename from tests/language_2/library/library6.dart
rename to tests/language_2/library/library6_test.dart
index a432958..fb089f9 100644
--- a/tests/language_2/library/library6.dart
+++ b/tests/language_2/library/library6_test.dart
@@ -4,12 +4,9 @@
 
 // @dart = 2.9
 
-// This tests that it is a compile-time error to both import a library
+// This tests that it is not a compile-time error to both import a library
 // that defines a function type alias and to have a local definition for
 // another function type alias with the same name.
-// This name conflict is considered an error even if Fun is never referred to.
-
-library Library6NegativeTest.dart;
 
 import "library5a.dart"; // Defines function type alias Fun
 
diff --git a/tests/language_2/prefix/new_test.dart b/tests/language_2/prefix/new_test.dart
index a056bdf..8eac176 100644
--- a/tests/language_2/prefix/new_test.dart
+++ b/tests/language_2/prefix/new_test.dart
@@ -7,7 +7,7 @@
 library PrefixTest;
 
 import "package:expect/expect.dart";
-import "test1.dart";
+import "new_test1.dart";
 
 main() {
   Expect.equals(Prefix.getSource(), Prefix.getImport() + 1);
diff --git a/tests/language_2/prefix/new_test1.dart b/tests/language_2/prefix/new_test1.dart
index 98c0e76..05681ee 100644
--- a/tests/language_2/prefix/new_test1.dart
+++ b/tests/language_2/prefix/new_test1.dart
@@ -6,7 +6,7 @@
 
 library PrefixTest1;
 
-import "test2.dart" as test2;
+import "new_test2.dart" as test2;
 
 class Prefix {
   static const int foo = 43;
diff --git a/tools/VERSION b/tools/VERSION
index 81f1c04..bc449ec 100644
--- a/tools/VERSION
+++ b/tools/VERSION
@@ -27,5 +27,5 @@
 MAJOR 2
 MINOR 14
 PATCH 0
-PRERELEASE 149
+PRERELEASE 150
 PRERELEASE_PATCH 0
\ No newline at end of file