Fix cross-platform process creation in tests: use cmd /c more on Windows

[Copilot]

new ProcessBuilder("cat").start() is Unix-only. On Windows, cat doesn't exist, and using cmd /c type NUL as a substitute exits immediately rather than blocking on stdin — making any test that relies on process.isAlive() inherently flaky.

Before the change?

• JsonRpcClientTest and CliServerManagerTest used new ProcessBuilder("cat").start() to create a long-lived process for testing, which only works on Unix.

After the change?

• A startBlockingProcess() helper is added to both test classes. It selects the right command at runtime — cmd /c more on Windows (blocks on stdin until destroyed) and cat on Unix — ensuring consistent cross-platform behaviour.
• All 4 occurrences of new ProcessBuilder("cat").start() across the two test files are replaced:
  • JsonRpcClientTest — testIsConnectedWithProcess, testIsConnectedWithProcessDead, testGetProcessReturnsProcess
  • CliServerManagerTest — connectToServerStdioMode
• No other ProcessBuilder usages in the test suite required this fix (remaining usages invoke the real Copilot CLI or the npx tsx proxy server).

private static Process startBlockingProcess() throws IOException {
    boolean isWindows = System.getProperty("os.name").toLowerCase().contains("windows");
    return (isWindows ? new ProcessBuilder("cmd", "/c", "more") : new ProcessBuilder("cat")).start();
}

Pull request checklist

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)
• mvn spotless:apply has been run to format the code
• mvn clean verify passes locally

Does this introduce a breaking change?

• Yes
• No

---

[edburns]

@copilot did you get all the occurrences?

[Copilot]

@copilot did you get all the occurrences?

Yes — all occurrences are covered. The only ProcessBuilder("cat") calls in the test suite were in JsonRpcClientTest (3 uses) and CliServerManagerTest (1 use), all of which are now replaced with the cross-platform startBlockingProcess() helper. The remaining ProcessBuilder usages in other tests (CopilotClientTest, MetadataApiTest, E2ETestContext) all invoke the real copilot CLI and don't need this fix.

[Copilot]

Pull request overview

Updates unit tests to create a long-lived dummy stdio process in a cross-platform way (Windows vs Unix), improving reliability of process.isAlive()-based assertions in the SDK’s process-backed JSON-RPC client and CLI server manager tests.

Changes:

• Added a startBlockingProcess() helper in JsonRpcClientTest to use cmd /c more on Windows and cat elsewhere.
• Added the same helper in CliServerManagerTest and replaced the stdio dummy process creation.
• Replaced all occurrences of new ProcessBuilder("cat").start() in the affected tests.

Show a summary per file

File	Description
src/test/java/com/github/copilot/sdk/JsonRpcClientTest.java	Uses an OS-specific blocking process helper to make process-backed connection tests work on Windows.
src/test/java/com/github/copilot/sdk/CliServerManagerTest.java	Uses the same blocking process helper for stdio-mode connection testing on Windows.

Copilot's findings

• Files reviewed: 2/2 changed files
• Comments generated: 2

[Copilot]

The startBlockingProcess() helper is duplicated here and in CliServerManagerTest. Consider extracting it into a shared test utility (e.g., a package-private helper in src/test/java/com/github/copilot/sdk/) so future tweaks to the blocking command/OS detection only need to be made in one place.

[Copilot]

This startBlockingProcess() helper is identical to the one added in JsonRpcClientTest. Consider extracting it into a shared test utility to avoid duplication and keep the OS-specific command logic consistent across tests.