rest - filter string constant path http properties when using `@autoR…

…oute` (microsoft#6326)

microsoft#6311 switched openapi3 to use `HttpProperty` instead of
`HttpOperationParameter`. The `@typespec/rest` package did some
filtering of parameters under a couple conditions (including path
constants) that wasn't applied to properties. This caused an extra path
parameter to be emitted in OpenAPI3 (and typespec-autorest when
eventually applying the same changes there).

This PR applies the same `@autoRoute` parameter filtering to properties.

---------

Co-authored-by: Christopher Radek <[email protected]>

.chronus/changes/rest-prop-filtering-2025-2-7-9-50-32.md

@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@typespec/rest"
+---
+
+Updates `@autoRoute` behavior to apply same HttpOperationParameter filtering to HttpProperty

packages/rest/src/rest.ts

@@ -111,6 +111,7 @@ function autoRouteProducer(
   const routePath = getRoutePath(program, operation)?.path;
   const segments = [...parentSegments, ...(routePath ? [routePath] : [])];
   const filteredParameters: HttpOperationParameter[] = [];
+  const filteredParamProperties = new Set<ModelProperty>();
   const paramOptions = {
     ...(options?.paramOptions ?? {}),
     verbSelector: getResourceOperationHttpVerb,
@@ -146,10 +147,21 @@ function autoRouteProducer(
 
     // Push all usable parameters to the filtered list
     filteredParameters.push(httpParam);
+    filteredParamProperties.add(httpParam.param);
   }
 
   // Replace the original parameters with filtered set
   parameters.parameters = filteredParameters;
+  // Remove any header/query/path/cookie properties that aren't in the filtered list
+  for (let i = parameters.properties.length - 1; i >= 0; i--) {
+    const httpProp = parameters.properties[i];
+    if (!["header", "query", "path", "cookie"].includes(httpProp.kind)) {
+      continue;
+    }
+    if (!filteredParamProperties.has(httpProp.property)) {
+      parameters.properties.splice(i, 1);
+    }
+  }
 
   // Add the operation's own segment if present
   addSegmentFragment(program, operation, segments);

packages/rest/test/routes.test.ts

@@ -143,7 +143,7 @@ describe("rest: routes", () => {
   });
 
   it("autoRoute operations filter out path parameters with a string literal type", async () => {
-    const routes = await getRoutesFor(
+    const operations = await getOperations(
       `
       model ThingId {
         @path
@@ -167,16 +167,60 @@ describe("rest: routes", () => {
       }
       `,
     );
-
-    deepStrictEqual(routes, [
-      {
-        verb: "get",
-        path: "/subscriptions/{subscriptionId}/providers/Microsoft.Things/things/{thingId}",
-        params: ["subscriptionId", "thingId"],
-      },
+    expect(operations.length).toBe(1);
+    const operation = operations[0];
+    expect(operation.verb).toBe("get");
+    expect(operation.path).toBe(
+      "/subscriptions/{subscriptionId}/providers/Microsoft.Things/things/{thingId}",
+    );
+    const operationParams = operation.parameters.parameters;
+    const operationProps = operation.parameters.properties;
+    expect(operationParams.map((p) => p.name)).toEqual(["subscriptionId", "thingId"]);
+    expect(operationProps.map((p) => (p as any).options.name)).toEqual([
+      "subscriptionId",
+      "thingId",
     ]);
   });
 
+  it("autoRoute operations does not filter out non-param http properties", async () => {
+    const operations = await getOperations(
+      `
+      model ThingId {
+        @path
+        @segment("things")
+        thingId: string;
+      }
+
+      @autoRoute
+      interface Things {
+        @put
+        op WithFilteredParam(
+          @path
+          @segment("subscriptions")
+          subscriptionId: string,
+
+          @path
+          @segment("providers")
+          provider: "Microsoft.Things",
+          ...ThingId,
+
+          @header contentType: "text/plain",
+
+          @body body: "Test Content"
+        ): string;
+      }
+      `,
+    );
+    expect(operations.length).toBe(1);
+    const operation = operations[0];
+    expect(operation.verb).toBe("put");
+    expect(operation.path).toBe(
+      "/subscriptions/{subscriptionId}/providers/Microsoft.Things/things/{thingId}",
+    );
+    const operationProps = operation.parameters.properties;
+    expect(operationProps.map((p) => p.kind)).toEqual(["path", "path", "contentType", "body"]);
+  });
+
   it("emit diagnostic if passing arguments to autoroute decorators", async () => {
     const [_, diagnostics] = await compileOperations(`
       @autoRoute("/test") op test(): string;