feat: add examples to README

README.md

@@ -1,9 +1,236 @@
-@oclif/test
-============
+# @oclif/test
 
-test helpers for oclif components
+test helpers for oclif CLIs
 
 [![Version](https://img.shields.io/npm/v/@oclif/test.svg)](https://npmjs.org/package/@oclif/test)
 [![Known Vulnerabilities](https://snyk.io/test/npm/@oclif/test/badge.svg)](https://snyk.io/test/npm/@oclif/test)
 [![Downloads/week](https://img.shields.io/npm/dw/@oclif/test.svg)](https://npmjs.org/package/@oclif/test)
 [![License](https://img.shields.io/npm/l/@oclif/test.svg)](https://github.com/oclif/test/blob/main/package.json)
+
+## Usage
+
+`@oclif/test` is an extension of [fancy-test](https://github.com/oclif/fancy-test). Please see the [fancy-test documentation](https://github.com/oclif/fancy-test#fancy-test) for all the features that are available.
+
+The following are the features that `@oclif/test` adds to `fancy-test`.
+
+### `.loadConfig()`
+
+`.loadConfig()` creates and returns a new [`Config`](https://github.com/oclif/core/blob/main/src/config/config.ts) instance. This instance will be available on the `ctx` variable that's provided in the callback.
+
+```typescript
+import {join} from 'node:path'
+import {expect, test} from '@oclif/test'
+
+const root = join(__dirname, 'fixtures/test-cli')
+test
+  .loadConfig({root})
+  .stdout()
+  .command(['foo:bar'])
+  .it('should run the command from the given directory', (ctx) => {
+    expect(ctx.stdout).to.equal('hello world!\n')
+    expect(ctx.config.root).to.equal(root)
+    const {name} = ctx.returned as {name: string}
+    expect(name).to.equal('world')
+  })
+```
+
+If you would like to run the same test without using `@oclif/test`:
+
+```typescript
+import {Config, ux} from '@oclif/core'
+import {expect} from 'chai'
+import {join} from 'node:path'
+import {SinonSandbox, SinonStub, createSandbox} from 'sinon'
+
+const root = join(__dirname, 'fixtures/test-cli')
+describe('non-fancy test', () => {
+  let sandbox: SinonSandbox
+  let config: Config
+  let stdoutStub: SinonStub
+
+  beforeEach(async () => {
+    sandbox = createSandbox()
+    stdoutStub = sandbox.stub(ux.write, 'stdout')
+    config = await Config.load({root})
+  })
+
+  afterEach(async () => {
+    sandbox.restore()
+  })
+
+  it('should run command from the given directory', async () => {
+    const {name} = await config.runCommand<{name: string}>('foo:bar')
+    expect(stdoutStub.calledWith('hello world!\n')).to.be.true
+    expect(config.root).to.equal(root)
+    expect(name).to.equal('world')
+  })
+})
+```
+
+### `.command()`
+
+`.command()` let's you run a command from your CLI.
+
+```typescript
+import {expect, test} from '@oclif/test'
+
+describe('hello world', () => {
+  test
+    .stdout()
+    .command(['hello:world'])
+    .it('runs hello world cmd', (ctx) => {
+      expect(ctx.stdout).to.contain('hello world!')
+    })
+})
+```
+
+For a [single command cli](https://oclif.io/docs/single_command_cli) you would provide `'.'` as the command. For instance:
+
+```typescript
+import {expect, test} from '@oclif/test'
+
+describe('hello world', () => {
+  test
+    .stdout()
+    .command(['.'])
+    .it('runs hello world cmd', (ctx) => {
+      expect(ctx.stdout).to.contain('hello world!')
+    })
+})
+```
+
+If you would like to run the same test without using `@oclif/test`:
+
+```typescript
+import {Config, ux} from '@oclif/core'
+import {expect} from 'chai'
+import {SinonSandbox, SinonStub, createSandbox} from 'sinon'
+
+describe('non-fancy test', () => {
+  let sandbox: SinonSandbox
+  let config: Config
+  let stdoutStub: SinonStub
+
+  beforeEach(async () => {
+    sandbox = createSandbox()
+    stdoutStub = sandbox.stub(ux.write, 'stdout')
+    config = await Config.load({root: process.cwd()})
+  })
+
+  afterEach(async () => {
+    sandbox.restore()
+  })
+
+  it('should run command', async () => {
+    // use '.' for a single command CLI
+    const {name} = await config.runCommand<{name: string}>('hello:world')
+    expect(stdoutStub.calledWith('hello world!\n')).to.be.true
+    expect(name).to.equal('world')
+  })
+})
+```
+
+### `.exit()`
+
+`.exit()` let's you test that a command exited with a certain exit code.
+
+```typescript
+import {join} from 'node:path'
+import {expect, test} from '@oclif/test'
+
+describe('exit', () => {
+  test
+    .loadConfig()
+    .stdout()
+    .command(['hello:world', '--code=101'])
+    .exit(101)
+    .do((output) => expect(output.stdout).to.equal('exiting with code 101\n'))
+    .it('should exit with code 101')
+})
+```
+
+If you would like to run the same test without using `@oclif/test`:
+
+```typescript
+import {Config, Errors, ux} from '@oclif/core'
+import {expect} from 'chai'
+import {SinonSandbox, createSandbox} from 'sinon'
+
+describe('non-fancy test', () => {
+  let sandbox: SinonSandbox
+  let config: Config
+
+  beforeEach(async () => {
+    sandbox = createSandbox()
+    sandbox.stub(ux.write, 'stdout')
+    config = await Config.load({root: process.cwd()})
+  })
+
+  afterEach(async () => {
+    sandbox.restore()
+  })
+
+  it('should run command from the given directory', async () => {
+    try {
+      await config.runCommand('.')
+      throw new Error('Expected CLIError to be thrown')
+    } catch (error) {
+      if (error instanceof Errors.CLIError) {
+        expect(error.oclif.exit).to.equal(101)
+      } else {
+        throw error
+      }
+    }
+  })
+})
+```
+
+### `.hook()`
+
+`.hook()` let's you test a hook in your CLI.
+
+```typescript
+import {join} from 'node:path'
+
+import {expect, test} from '@oclif/test'
+
+const root = join(__dirname, 'fixtures/test-cli')
+
+describe('hooks', () => {
+  test
+    .loadConfig({root})
+    .stdout()
+    .hook('foo', {argv: ['arg']}, {root})
+    .do((output) => expect(output.stdout).to.equal('foo hook args: arg\n'))
+    .it('should run hook')
+})
+```
+
+If you would like to run the same test without using `@oclif/test`:
+
+```typescript
+import {Config, ux} from '@oclif/core'
+import {expect} from 'chai'
+import {SinonSandbox, SinonStub, createSandbox} from 'sinon'
+
+describe('non-fancy test', () => {
+  let sandbox: SinonSandbox
+  let config: Config
+  let stdoutStub: SinonStub
+
+  beforeEach(async () => {
+    sandbox = createSandbox()
+    stdoutStub = sandbox.stub(ux.write, 'stdout')
+    config = await Config.load({root: process.cwd()})
+  })
+
+  afterEach(async () => {
+    sandbox.restore()
+  })
+
+  it('should run hook', async () => {
+    const {name} = await config.runHook('foo', {argv: ['arg']})
+    expect(stdoutStub.calledWith('foo hook args: arg\n')).to.be.true
+  })
+})
+```