fix(websocket): throw on ExecutionContext.switchToRpc()

[mvanhorn]

What changed

src/websocket/middleware/guards/guard-executor.ts and src/websocket/middleware/filters/exception-filter-executor.ts: replaced the switchToRpc adapter (which previously returned a fake RPC context wrapping the WebSocket client and data) with a throwing implementation that mirrors the existing switchToHttp behavior:

switchToRpc: () => {
  throw new Error('RPC context not available in WebSocket');
},

Added two unit tests — one in guard-executor.spec.ts, one in exception-filter-executor.spec.ts — that build a guard / filter calling context.switchToRpc() and assert the throw.

Closes #89

Why

Issue #89 calls out that the existing switchToRpc returns a fake context whose getContext() and getData() map WebSocket fields into RPC slots. That's semantically wrong — the execution context is never an RPC context. The expected behavior, per the NestJS reference linked in the issue (packages/core/helpers/execution-context-host.ts), is that the wrong-context switches throw. The codebase already does this for switchToHttp; this PR makes switchToRpc symmetric.

Verification

npx jest src/websocket/middleware/guards/guard-executor.spec.ts src/websocket/middleware/filters/exception-filter-executor.spec.ts runs 33/33 green, including the two new tests. The new tests use the same gateway construction and execution invocation pattern as the existing switchToWs tests in those files.

Summary by CodeRabbit

• Bug Fixes

  • WebSocket exception and guard handlers now throw a clear error when attempting to access RPC context, preventing unsupported operations.

• Tests

  • Added test coverage for WebSocket RPC context restrictions.

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Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/websocket/middleware/filters/exception-filter-executor.spec.ts`:
- Around line 146-162: The test currently relies on an assertion inside
RpcCheckFilter.catch which can be swallowed by ExceptionFilterExecutor.catch;
instead have the filter call host.switchToRpc() so it throws naturally and
assert on executor.catch itself: update RpcCheckFilter.catch to simply invoke
host.switchToRpc() (no expect inside the filter), then call await
expect(executor.catch(new Error('Test'), host)).rejects.toThrow('RPC context not
available in WebSocket'); keep references to ExceptionFilterExecutor.catch
(executor.catch), RpcCheckFilter.catch, TestGateway and createHost to locate the
code.

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📥 Commits

Reviewing files that changed from the base of the PR and between e8c673e and 9f3b11d.

📒 Files selected for processing (4)

• src/websocket/middleware/filters/exception-filter-executor.spec.ts
• src/websocket/middleware/filters/exception-filter-executor.ts
• src/websocket/middleware/guards/guard-executor.spec.ts
• src/websocket/middleware/guards/guard-executor.ts

[VikramAditya33]

@mvanhorn LGTM, Thank you