Support optional path parameter for Modular

packages/typespec-ts/test/modularUnit/scenarios/operations/emptyOperation.md

@@ -0,0 +1,55 @@
+# generate empty operation for classic client
+
+## TypeSpec
+
+```tsp
+model Test {
+  @query
+  "api-version": string;
+}
+model Foo {
+    id: string;
+}
+op test(): string;
+```
+
+## models
+
+```ts models
+// (file was not generated)
+```
+
+## classicClient
+
+```ts classicClient
+import { TestOptionalParams } from "./api/options.js";
+import { test } from "./api/operations.js";
+import { Pipeline } from "@azure/core-rest-pipeline";
+
+export { TestingClientOptionalParams } from "./api/testingContext.js";
+
+export class TestingClient {
+  private _client: TestingContext;
+  /** The pipeline used by this client to make requests */
+  public readonly pipeline: Pipeline;
+
+  constructor(
+    endpointParam: string,
+    options: TestingClientOptionalParams = {}
+  ) {
+    const prefixFromOptions = options?.userAgentOptions?.userAgentPrefix;
+    const userAgentPrefix = prefixFromOptions
+      ? `${prefixFromOptions} azsdk-js-client`
+      : `azsdk-js-client`;
+    this._client = createTesting(endpointParam, {
+      ...options,
+      userAgentOptions: { userAgentPrefix }
+    });
+    this.pipeline = this._client.pipeline;
+  }
+
+  test(options: TestOptionalParams = { requestOptions: {} }): Promise<string> {
+    return test(this._client, options);
+  }
+}
+```