fix: update testing docs

docs/testing.md

@@ -5,23 +5,22 @@ description: How to test your CLI
 
 Testing in oclif can be done with any testing framework. You can run commands with `MyCommand.run()` which returns a promise you can wait on.
 
-There are common tasks however when writing CLI tools. For this, we have a conventional set of tools that we suggest using to test your CLI. These are based on [mocha](https://mochajs.org) and [fancy-test](https://github.com/jdxcode/fancy-test).
+There are common tasks however when writing CLI tools. For this, we have [@oclif/test](https://github.com/oclif/test), which provides a [conventional set of utilities](https://github.com/oclif/test?tab=readme-ov-file#usage) that we find useful for testing oclif CLIs.
 
-Mocha is the top JavaScript testing framework and a solid choice for any project. fancy-test is a tool we developed that builds on top of mocha to make it easy to repeat patterns and write concise mocha tests. There is also a library [@oclif/test](https://github.com/oclif/test) that extends fancy-test with helpers specific to testing oclif CLIs. These are things like running a command or hook or checking if an exit status code is set, for example.
+Any CLI built with oclif will come preloaded with [mocha](https://www.npmjs.com/package/mocha) (our preferred testing framework but you're free to use whatever you prefer) and [@oclif/test](https://github.com/oclif/test) as well as an example test that should work out of the box with `npm test` or `yarn test`.
 
-Any CLI built with oclif will come preloaded with these tools and an example test that should work out of the box with `npm test` or `yarn test`.
 
-As an example, let's look at the `heroku whoami` command which makes an API call to get the current logged in user. If the user is not logged in, it exits with status 100. (This is a simplified example, here is [the actual code](https://github.com/heroku/heroku-cli-plugin-auth).)
+As an example, let's look at this `whoami` command which makes an API call to get the current logged in user. If the user is not logged in, it exits with status 100.
 
 **src/commands/whoami.ts**
 
 ```js
-import Command from '@heroku-cli/command'
+import {Command} from '@oclif/core'
 
 export class Whoami extends Command {
   async run() {
     try {
-      let {body: account} = await this.heroku.get('/account')
+      let {body: account} = await this.api.get('/account')
       this.log(account.email)
     } catch (err) {
       if (err.statusCode === 401) {
@@ -40,43 +39,34 @@ Here is the test code
 **test/commands/whoami.test.ts**
 
 ```typescript
-import {expect, test} from '@oclif/test'
-
-describe('auth:whoami', () => {
-  test
-  .nock('https://api.heroku.com', api => api
-    .get('/account')
-    // user is logged in, return their name
-    .reply(200, {email: '[email protected]'})
-  )
-  .stdout()
-  .command(['auth:whoami'])
-  .it('shows user email when logged in', ctx => {
-    expect(ctx.stdout).to.equal('[email protected]\n')
+import {runCommand} from '@oclif/test'
+import {expect} from 'chai'
+import nock from 'nock'
+
+describe('whoami', () => {
+  it('shows user email when logged in', async () => {
+    nock('https://api.example.com')
+      .get('/account')
+      // user is logged in, return their name
+      .reply(200, {email: '[email protected]'})
+
+    const {stdout} = await runCommand('whoami')
+    expect(stdout).to.equal('[email protected]')
   })
 
-  test
-  .nock('https://api.heroku.com', api => api
-    .get('/account')
-    // HTTP 401 means the user is not logged in with valid credentials
-    .reply(401)
-  )
-  .command(['auth:whoami'])
-  // checks to ensure the command exits with status 100
-  .exit(100)
-  .it('exits with status 100 when not logged in')
+  it('exits with status 100 when not logged in', async () => {
+    nock('https://api.example.com')
+      .get('/account')
+      // HTTP 401 means the user is not logged in with valid credentials
+      .reply(401)
+
+    const {error} = await runCommand('whoami')
+    expect(error?.oclif?.exit).to.equal(100)
+  })
 })
 ```
 
-These tools are setup to not only mock out the stdout/stderr and HTTP calls, but they're setup to ensure they automatically reset after the test. A common issue we've had when building CLIs with simpler `beforeEach/afterEach` filters is that if the `afterEach` filters aren't setup correctly, a failing test can leave mocks around that make later tests fail. Using fancy-test, we avoid this problem and only have to declare our mocks once.
-
-For more on how to test with oclif, check out the docs for [fancy-test](https://github.com/jdxcode/fancy-test) and [@oclif/test](https://github.com/oclif/test).
-
-## stdout/stderr
-
-The stdout/stderr mocks use [stdout-stderr](https://github.com/jdxcode/stdout-stderr) under the hood. This library can be used standalone if you'd prefer to use jest or want a different testing setup but still have the ability to mock out stdout and stderr.
-
-If you want to see the output but leave it mocked, you can either pass in `{print: true}` to the options, or set `TEST_OUTPUT=1`.
+For more on how to test with oclif, check out the docs for [@oclif/test](https://github.com/oclif/test).
 
 ## Code Coverage