[tcgc] take lro finalResult into consideration (#559)

fixes #124

---------

Co-authored-by: iscai-msft <isabellavcai@gmail.com>
Co-authored-by: Joel Hendrix <jhendrix@microsoft.com>
Co-authored-by: tadelesh <tadelesh.shi@live.cn>

.chronus/changes/lro_response-2024-3-1-10-55-55.md

@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@azure-tools/typespec-client-generator-core"
+---
+
+take lroMetadata.finalResult into consideration

packages/typespec-client-generator-core/src/package.ts

@@ -163,15 +163,16 @@ function getSdkLroServiceMethod<
     getSdkBasicServiceMethod<TOptions, TServiceOperation>(context, operation)
   );
 
-  basicServiceMethod.response.type = diagnostics.pipe(
-    getClientTypeWithDiagnostics(context, metadata.logicalResult)
-  );
-  basicServiceMethod.response.resultPath =
-    metadata.logicalPath ??
-    (metadata.envelopeResult !== metadata.logicalResult &&
-    basicServiceMethod.operation.verb === "post"
-      ? "result"
-      : undefined);
+  if (metadata.finalResult === undefined || metadata.finalResult === "void") {
+    basicServiceMethod.response.type = undefined;
+  } else {
+    basicServiceMethod.response.type = diagnostics.pipe(
+      getClientTypeWithDiagnostics(context, metadata.finalResult)
+    );
+  }
+
+  basicServiceMethod.response.resultPath = metadata.finalResultPath;
+
   return diagnostics.wrap({
     ...basicServiceMethod,
     kind: "lro",

packages/typespec-client-generator-core/test/package.test.ts

@@ -2596,6 +2596,23 @@ describe("typespec-client-generator-core: package", () => {
       strictEqual(methodResponse.type, widgetModel);
       strictEqual(createOrUpdate.response.resultPath, "result");
     });
+    it("lro delete", async () => {
+      const runnerWithCore = await createSdkTestRunner({
+        librariesToAdd: [AzureCoreTestLibrary],
+        autoUsings: ["Azure.Core", "Azure.Core.Traits"],
+        emitterName: "@azure-tools/typespec-java",
+      });
+      await compileAzureWidgetService(
+        runnerWithCore,
+        `
+        op delete is ResourceOperations.LongRunningResourceDelete<Widget>;
+        `
+      );
+      const method = getServiceMethodOfClient(runnerWithCore.context.experimental_sdkPackage);
+      strictEqual(method.name, "delete");
+      strictEqual(method.kind, "lro");
+      strictEqual(method.response.type, undefined);
+    });
     it("paging", async () => {
       const runnerWithCore = await createSdkTestRunner({
         librariesToAdd: [AzureCoreTestLibrary],