Create a Modern Test Data Function

A test data function is a pure generator. It receives a parameter map and returns a single string. It has no UI adapters and cannot modify runtime variables, and that purity is what lets the platform call it anywhere a value is needed.

Prerequisites

• A Modern addon exists and its scaffold is downloaded.

Declare the Function

import { defineTestDataFunction } from "@testsigma/addon-sdk";
import { z } from "zod";

export const randomEmail = defineTestDataFunction({
  name: "random.email",
  description: "Generate a unique email address",
  parameters: z.object({
    domain: z.string().default("example.com").describe("Mail domain to use"),
  }),
  async generate({ domain }, ctx) {
    const local = `user-${Math.random().toString(36).slice(2, 10)}`;
    ctx.logger.info("generated email", { domain });
    return `${local}@${domain}`;
  },
});

Declaration Fields

A function that calls an external API declares the host it contacts, for example permissions: { net: ["erp.example.com"] }.

What the Context Provides

ctx gives you tmpDir, signal, logger, and execution. There is no UI adapter and no runtime variable store.

Where Test Authors Use It

• Step test data, in any field that accepts a data generator
• For-loop conditions, as the left or right bound
• Step group parameter overrides

Write for Idempotence

The platform may cache a result within a run when the function is invoked with identical parameters. A loop bound, for example, is computed once per loop rather than once per iteration.