test: verify input flags

This makes sure all required flags are passed through to the test.
If that's not the case an error is thrown to inform the user what
flag is missing.
PR-URL: #24876
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Rich Trott <rtrott@gmail.com>

Author: BridgeAR

test/common/index.js

@@ -45,6 +45,44 @@ const isMainThread = (() => {
 }
 })();
 
+// Check for flags. Skip this for workers (both, the `cluster` module and
+// `worker_threads`) and child processes.
+if(process.argv.length===2&&
+isMainThread&&
+module.parent&&
+require('cluster').isMaster){
+// The copyright notice is relatively big and the flags could come afterwards.
+constbytesToRead=1500;
+constbuffer=Buffer.allocUnsafe(bytesToRead);
+constfd=fs.openSync(module.parent.filename,'r');
+fs.readSync(fd,buffer,0,bytesToRead);
+fs.closeSync(fd);
+constsource=buffer.toString();
+
+constflagStart=source.indexOf('// Flags: --')+10;
+if(flagStart!==9){
+letflagEnd=source.indexOf('\n',flagStart);
+// Normalize different EOL.
+if(source[flagEnd-1]==='\r'){
+flagEnd--;
+}
+constflags=source
+.substring(flagStart,flagEnd)
+.replace(/_/g,'-')
+.split(' ');
+constargs=process.execArgv.map((arg)=>arg.replace(/_/g,'-'));
+for(constflagofflags){
+if(!args.includes(flag)&&
+// If the binary is build without `intl` the inspect option is
+// invalid. The test itself should handle this case.
+(process.config.variables.v8_enable_inspector!==0||
+!flag.startsWith('--inspect'))){
+thrownewError(`Test has to be started with the flag: '${flag}'`);
+}
+}
+}
+}
+
 constisWindows=process.platform==='win32';
 constisAIX=process.platform==='aix';
 constisLinuxPPCBE=(process.platform==='linux')&&