[native_toolchain_c] Disallow test skips on CI (#3438)

Co-authored-by: Liam Appelbe <liama@google.com>

Author: dcharkes

pkgs/native_test_helpers/lib/native_test_helpers.dart

@@ -3,4 +3,5 @@
 // BSD-style license that can be found in the LICENSE file.
 
 export 'src/find_package_root.dart';
+export 'src/skip_local.dart';
 export 'src/yaml_to_json.dart';

pkgs/native_test_helpers/lib/src/skip_local.dart

@@ -0,0 +1,25 @@
+// Copyright (c) 2026, 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 'dart:io';
+
+/// Returns a skip reason if the [condition] is met and we are running locally.
+///
+/// Returns `null` (forcing the test or expectation to run) if running on CI
+/// (detected by the `GITHUB_ACTIONS` environment variable).
+// ignore: avoid_positional_boolean_parameters
+Object? skipLocal(bool condition, String reason) {
+  // Disallow skips when running in CI environments, where all toolchains and
+  // dependencies must be present.
+  final isGithubActions = Platform.environment.containsKey('GITHUB_ACTIONS');
+
+  // The Dart SDK's internal CI infrastructure (Buildbot / Swarming).
+  final isDartSdkCI =
+      Platform.environment.containsKey('BUILDBOT_BUILDERNAME') ||
+      Platform.environment.containsKey('SWARMING_TASK_ID');
+
+  final isCI = isGithubActions || isDartSdkCI;
+  if (isCI) return null;
+  return condition ? reason : null;
+}

pkgs/native_toolchain_c/test/cbuilder/cbuilder_cross_macos_host_test.dart

@@ -13,6 +13,7 @@ import 'dart:io';
 import 'package:code_assets/code_assets.dart';
 import 'package:hooks/hooks.dart';
 import 'package:logging/logging.dart';
+import 'package:native_test_helpers/native_test_helpers.dart';
 import 'package:native_toolchain_c/native_toolchain_c.dart';
 import 'package:native_toolchain_c/src/native_toolchain/apple_clang.dart';
 import 'package:native_toolchain_c/src/native_toolchain/clang.dart';
@@ -202,7 +203,10 @@ void main() async {
         );
         await expectMachineArchitecture(libUri, arch, os);
       },
-      skip: os == OS.linux && !lldAvailable ? 'ld.lld not available' : null,
+      skip: skipLocal(
+        os == OS.linux && !lldAvailable,
+        'ld.lld not available',
+      ),
     );
   }
 

pkgs/native_toolchain_c/test/clinker/objects_helper.dart

@@ -6,6 +6,7 @@ import 'dart:io';
 
 import 'package:code_assets/code_assets.dart';
 import 'package:hooks/hooks.dart';
+import 'package:native_test_helpers/native_test_helpers.dart';
 import 'package:native_toolchain_c/native_toolchain_c.dart';
 import 'package:test/test.dart';
 
@@ -99,7 +100,10 @@ void runObjectsTests(
       expect(
         symbols,
         stringContainsInOrder(['my_func', 'my_other_func']),
-        skip: symbols == null ? 'tool to extract symbols unavailable' : false,
+        skip: skipLocal(
+          symbols == null,
+          'tool to extract symbols unavailable',
+        ),
       );
     });
   }

pkgs/native_toolchain_c/test/clinker/rust_test.dart

@@ -6,6 +6,7 @@ import 'dart:io';
 
 import 'package:code_assets/code_assets.dart';
 import 'package:hooks/hooks.dart';
+import 'package:native_test_helpers/native_test_helpers.dart';
 import 'package:native_toolchain_c/native_toolchain_c.dart';
 import 'package:test/test.dart';
 
@@ -67,11 +68,12 @@ Future<void> main() async {
       targetArchitecture,
       targetOS,
     );
-    final skipReason = symbols == null
-        ? 'tool to extract symbols unavailable'
-        : false;
-    expect(symbols, contains('my_other_func'), skip: skipReason);
-    expect(symbols, isNot(contains('my_func')), skip: skipReason);
+    final skip = skipLocal(
+      symbols == null,
+      'tool to extract symbols unavailable',
+    );
+    expect(symbols, contains('my_other_func'), skip: skip);
+    expect(symbols, isNot(contains('my_func')), skip: skip);
   });
 
   test('link rust binary without script keeps symbols', () async {
@@ -91,11 +93,12 @@ Future<void> main() async {
       targetArchitecture,
       targetOS,
     );
-    final skipReason = symbols == null
-        ? 'tool to extract symbols unavailable'
-        : false;
-    expect(symbols, contains('my_other_func'), skip: skipReason);
-    expect(symbols, contains('my_func'), skip: skipReason);
+    final skip = skipLocal(
+      symbols == null,
+      'tool to extract symbols unavailable',
+    );
+    expect(symbols, contains('my_other_func'), skip: skip);
+    expect(symbols, contains('my_func'), skip: skip);
   });
 }
 

pkgs/native_toolchain_c/test/clinker/treeshake_helper.dart

@@ -6,6 +6,7 @@ import 'dart:io';
 
 import 'package:code_assets/code_assets.dart';
 import 'package:hooks/hooks.dart';
+import 'package:native_test_helpers/native_test_helpers.dart';
 import 'package:native_toolchain_c/native_toolchain_c.dart';
 import 'package:test/test.dart';
 
@@ -151,15 +152,16 @@ void runTreeshakeTests(
       );
 
       final symbols = await readSymbols(asset, targetOS);
-      final skipReason = symbols == null
-          ? 'tool to extract symbols unavailable'
-          : false;
+      final skip = skipLocal(
+        symbols == null,
+        'tool to extract symbols unavailable',
+      );
       if (clinker.linker != linkerAutoKeepAll) {
-        expect(symbols, contains('my_other_func'), skip: skipReason);
-        expect(symbols, isNot(contains('my_func')), skip: skipReason);
+        expect(symbols, contains('my_other_func'), skip: skip);
+        expect(symbols, isNot(contains('my_func')), skip: skip);
       } else {
-        expect(symbols, contains('my_other_func'), skip: skipReason);
-        expect(symbols, contains('my_func'), skip: skipReason);
+        expect(symbols, contains('my_other_func'), skip: skip);
+        expect(symbols, contains('my_func'), skip: skip);
       }
 
       final sizeInBytes = await File.fromUri(asset.file!).length();

pkgs/native_toolchain_c/test/clinker/windows_module_definition_helper.dart

@@ -6,6 +6,7 @@ import 'dart:io';
 
 import 'package:code_assets/code_assets.dart';
 import 'package:hooks/hooks.dart';
+import 'package:native_test_helpers/native_test_helpers.dart';
 import 'package:native_toolchain_c/native_toolchain_c.dart';
 import 'package:test/test.dart';
 
@@ -69,14 +70,15 @@ void runWindowsModuleDefinitionTests(List<Architecture> architectures) {
         final asset = codeAssets.first;
         expect(asset, isA<CodeAsset>());
         final symbols = await readSymbols(asset, targetOS);
-        final skipReason = symbols == null
-            ? 'tool to extract symbols unavailable'
-            : false;
-        expect(symbols, contains('my_func'), skip: skipReason);
+        final skip = skipLocal(
+          symbols == null,
+          'tool to extract symbols unavailable',
+        );
+        expect(symbols, contains('my_func'), skip: skip);
         // Module Definition file causes my_unexported_func to be exported even
         // though it wasn't marked for export.
-        expect(symbols, contains('my_unexported_func'), skip: skipReason);
-        expect(symbols, isNot(contains('my_other_func')), skip: skipReason);
+        expect(symbols, contains('my_unexported_func'), skip: skip);
+        expect(symbols, isNot(contains('my_other_func')), skip: skip);
       },
     );
   }

pkgs/native_toolchain_c/test/helpers.dart

@@ -446,14 +446,15 @@ Future<void> expectMachineArchitecture(
     );
   } else if (Platform.isWindows && targetOS == OS.windows) {
     final result = await _runDumpbin(['/HEADERS'], libUri);
-    final skipReason = result == null
-        ? 'tool to determine binary architecture unavailable'
-        : false;
-    expect(result?.exitCode, 0, skip: skipReason);
+    final skip = skipLocal(
+      result == null,
+      'tool to determine binary architecture unavailable',
+    );
+    expect(result?.exitCode, 0, skip: skip);
     final machine = result?.stdout
         .split('\n')
         .firstWhere((e) => e.contains('machine'));
-    expect(machine, contains(dumpbinFileFormat[targetArch]), skip: skipReason);
+    expect(machine, contains(dumpbinFileFormat[targetArch]), skip: skip);
   }
 }