Generated API wrapper returns undefined instead Date if the timestamp is 0

[davidyuk]

In OpenApi I have a type defined as

"value": {
 "type": "integer",
  "format": "unixtime"
}

In the generated api client it has a non-optional Date type. But in the application, I get undefined if the processed timestamp is 0.

I expect it to be new Date(0) or the generated type to be Date | undefined (not preferable).

Reproduction

OpenAPI schema

{
  "openapi": "3.0.0",
  "info": {
    "title": "Node",
    "version": "1.0.0"
  },
  "paths": {
    "/foo/{value}": {
      "get": {
        "operationId": "foo",
        "parameters": [
          {
            "in": "path",
            "name": "value",
            "required": true,
            "schema": {
              "type": "integer"
            }
          }
        ],
        "responses": {
          "200": {
            "description": "Successful operation",
            "content": {
              "application/json": {
                "schema": {
                  "type": "object",
                  "properties": {
                    "value": {
                      "type": "integer",
                      "format": "unixtime"
                    }
                  },
                  "required": ["value"]
                }
              }
            }
          }
        }
      }
    }
  }
}

autorest.yaml

version: ^3.7.1
use-extension:
  '@autorest/typescript': ^6.0.23
  '@autorest/modelerfour': ^4.27.0
input-file: ./api.json
output-folder: ./reproduction-api
source-code-folder-path: .
generator: typescript
generate-metadata: false
add-credentials: false

npm dependencies

  "dependencies": {
    "@azure/core-client": "^1.9.2",
    "@types/express": "^5.0.0",
    "autorest": "^3.7.1",
    "express": "^4.21.2",
    "tsx": "^4.19.2"
  }

reproduction.ts

import express, { Request, Response } from "express";

const app = express();

app.get("/foo/:value", (req: Request, res: Response) => {
  res.json({ value: +req.params.value });
});

app.listen(3000, () => {
  console.log("listening on port 3000");
});

import { Node } from "./reproduction-api/index";

const node = new Node("http://localhost:3000", {
  allowInsecureConnection: true,
});

(async () => {
  console.log("value", (await node.foo(42)).value);
  console.log("value", (await node.foo(0)).value);
})();

$ npx autorest ./autorest.yaml
$ npx tsx reproduction        
listening on port 3000
value 1970-01-01T00:00:42.000Z
value undefined

I expect it to print 1970-01-01T00:00:00.000Z instead undefined.

[xirzec]

Looks like this is happening because of this piece of code: https://github.com/Azure/azure-sdk-for-js/blob/e2a07dd899034ed223d085bae81e3aa49c0a998c/sdk/core/core-client/src/serializer.ts#L401

I'm not sure if any other services rely on the current 0 => undefined behavior, but really this should have been a check to see if the value was a number rather than using !n