How do I reuse the same API tests across dev and staging?

The best way is to keep the tests environment-agnostic and move all environment-specific values into config.

Practical approach

1) Put base URLs and secrets in per-environment config

Use separate config for dev and staging, for example:

• dev → https://dev.api.example.com
• staging → https://staging.api.example.com

Keep things like:

• baseUrl
• auth tokens
• tenant IDs
• test data seeds
• feature flags

out of the test code itself.

2) Make tests use variables, not hardcoded values

Instead of:

fetch("https://dev.api.example.com/users")

write:

fetch(`${baseUrl}/users`)

3) Load config based on environment

Example in JavaScript:

const env = process.env.TEST_ENV || "dev";

const config = {
  dev: {
    baseUrl: "https://dev.api.example.com",
    token: process.env.DEV_TOKEN,
  },
  staging: {
    baseUrl: "https://staging.api.example.com",
    token: process.env.STAGING_TOKEN,
  },
};

module.exports = config[env];

Then run:

TEST_ENV=dev npm test
TEST_ENV=staging npm test

4) Keep assertions focused on behavior

Avoid asserting environment-specific details unless required. For example:

• Good: status code is 200
• Good: response includes user id
• Avoid: exact timestamp value unless necessary

5) Use the same test data setup/teardown

If dev and staging have different state, add:

• seed scripts
• cleanup hooks
• isolated test accounts/resources

6) Parameterize anything that differs

Examples:

• user credentials
• IDs
• hostnames
• timeouts
• rate limits

If you use a test framework

Most frameworks support this directly:

• Postman/Newman: environments
• pytest: fixtures + config files
• JUnit/TestNG: profiles/properties
• Playwright / Cypress: config per project/environment
• pytest + requests: fixture for base_url

Recommended structure

tests/
  api/
    users.test.js
    orders.test.js
config/
  dev.json
  staging.json

Rule of thumb

If the test can be the same, keep it the same.
If only the endpoint/data differs, externalize that difference into config.

If you want, I can show you a concrete example in Postman, pytest, JUnit, or JavaScript.