add flag to allow pre-release

script/tool/lib/src/publish_check_command.dart

@@ -18,7 +18,17 @@ class PublishCheckCommand extends PluginCommand {
     Directory packagesDir,
     FileSystem fileSystem, {
     ProcessRunner processRunner = const ProcessRunner(),
-  }) : super(packagesDir, fileSystem, processRunner: processRunner);
+  }) : super(packagesDir, fileSystem, processRunner: processRunner) {
+    argParser.addFlag(
+      _allowPrereleaseFlag,
+      help: 'Allows the pre-release SDK warning to pass.'
+          'When enabled, a pub warning, which asks to publish the package as a pre-release version when'
+          'the SDK constraint is a pre-release version, is ignored.',
+      defaultsTo: false,
+    );
+  }
+
+  static const String _allowPrereleaseFlag = 'allow-pre-release';
 
   @override
   final String name = 'publish-check';
@@ -98,6 +108,10 @@ class PublishCheckCommand extends PluginCommand {
       return true;
     }
 
+    if (!(argResults[_allowPrereleaseFlag] as bool)) {
+      return false;
+    }
+
     await stdOutCompleter.future;
     await stdInCompleter.future;
 

script/tool/test/publish_check_command_test.dart

@@ -90,7 +90,7 @@ void main() {
           throwsA(isA<ToolExit>()));
     });
 
-    test('fail on prerelease', () async {
+    test('pass on prerelease is --allow-pre-release flag is on', () async {
       createFakePlugin('d');
 
       const String preReleaseOutput = 'Package has 1 warning.'
@@ -105,7 +105,8 @@ void main() {
 
       processRunner.processesToReturn.add(process);
 
-      expect(runner.run(<String>['publish-check']), throwsA(isA<ToolExit>()));
+      expect(runner.run(<String>['publish-check', '--allow-pre-release']),
+          completes);
     });
   });
 }