fix(tests): Failed to start process with command npx on Windows

[codeboyzhou]

Fixed an exception when I was performing unit testing with ./mvnw test on a Windows system:

reactor.core.Exceptions$ErrorCallbackNotImplemented: java.lang.RuntimeException: Failed to start process with command: [npx, -y, @modelcontextprotocol/server-everything, dir]
Caused by: java.lang.RuntimeException: Failed to start process with command: [npx, -y, @modelcontextprotocol/server-everything, dir]
        at io.modelcontextprotocol.client.transport.StdioClientTransport.lambda$connect$1(StdioClientTransport.java:132)
        at reactor.core.publisher.MonoRunnable.call(MonoRunnable.java:73)
        at reactor.core.publisher.MonoRunnable.call(MonoRunnable.java:32)
        at reactor.core.publisher.FluxSubscribeOnCallable$CallableSubscribeOnSubscription.run(FluxSubscribeOnCallable.java:228)
        at reactor.core.scheduler.SchedulerTask.call(SchedulerTask.java:68)
        at reactor.core.scheduler.SchedulerTask.call(SchedulerTask.java:28)
        at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
        at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
        at java.base/java.lang.Thread.run(Thread.java:840)
Caused by: java.io.IOException: Cannot run program "npx": CreateProcess error=2, System cannot find the file specified.
        at java.base/java.lang.ProcessBuilder.start(ProcessBuilder.java:1143)
        at java.base/java.lang.ProcessBuilder.start(ProcessBuilder.java:1073)
        at io.modelcontextprotocol.client.transport.StdioClientTransport.lambda$connect$1(StdioClientTransport.java:129)

Motivation and Context

As shown in the exception stack above, when I was running ./mvnw test, I got the exception.

I am using Windows 11 and I confirmed the environment variables of node and npx have been set correctly, because I can run node -v and npx -v in any terminal window and any time.

I attempted to change the related code like this and run ./mvnw test again, the exception disappeared, so I think it might be helpful to improve cross-platform compatibility.

ServerParameters.builder("cmd.exe")
    .args("/c", "npx.cmd", "-y", "@modelcontextprotocol/server-everything", "dir")
    .build();
boolean isWindows = System.getProperty("os.name").toLowerCase().contains("win");
return new StdioClientTransport(isWindows ? windowsStdioParams : stdioParams);

How Has This Been Tested?

No need more tests. Run exists tests.

Breaking Changes

No break changes

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

No additional context

[tzolov]

Thank you @codeboyzhou
I left few comments

[tzolov]

LGTM