fix(output): allow empty output (#35)

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<!-- What changes are being made? (What feature/bug is being fixed here?) -->
**What**:
Allowing expected `output` to be an empty string.

<!-- Why are these changes necessary? -->
**Why**:
There's cases when we just want to verify that a node gets removed.

<!-- How were these changes implemented? -->
**How**:
By removing the default behaviour of keeping `output` to be an empty string, and instead make it `undefined` if it isn't provided.

<!-- feel free to add additional comments -->
Bonus commits:
* Added a eslint rule to deny trailing semi colons.
* Upgraded kcd-scripts to make `npm run add-contributor` to work.

Author: kontrollanten

.all-contributorsrc

@@ -50,6 +50,16 @@
         "doc",
         "test"
       ]
+    },
+    {
+      "login": "kontrollanten",
+      "name": "kontrollanten",
+      "avatar_url": "https://avatars3.githubusercontent.com/u/6680299?v=4",
+      "profile": "https://github.com/kontrollanten",
+      "contributions": [
+        "code"
+      ]
     }
-  ]
+  ],
+  "repoType": "github"
 }

README.md

@@ -7,9 +7,9 @@ Utilities for testing babel plugins
 [![Dependencies][dependencyci-badge]][dependencyci]
 [![version][version-badge]][package]
 [![downloads][downloads-badge]][npm-stat]
-[![MIT License][license-badge]][LICENSE]
+[![MIT License][license-badge]][license]
 
-[![All Contributors](https://img.shields.io/badge/all_contributors-4-orange.svg?style=flat-square)](#contributors)
+[![All Contributors](https://img.shields.io/badge/all_contributors-5-orange.svg?style=flat-square)](#contributors)
 [![PRs Welcome][prs-badge]][prs]
 [![Donate][donate-badge]][donate]
 [![Code of Conduct][coc-badge]][coc]
@@ -30,6 +30,26 @@ This is a fairly simple abstraction to help you write tests for your babel
 plugin. It works with `jest` (my personal favorite) and most of it should also
 work with `mocha` and `jasmine`.
 
+<!-- START doctoc generated TOC please keep comment here to allow auto update -->
+<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
+
+- [Installation](#installation)
+- [Usage](#usage)
+  - [import](#import)
+  - [Invoke](#invoke)
+  - [options](#options)
+  - [Test Objects](#test-objects)
+- [Examples](#examples)
+  - [Full Example + Docs](#full-example--docs)
+  - [Simple Example](#simple-example)
+- [Inspiration](#inspiration)
+- [Other Solutions](#other-solutions)
+- [Contributors](#contributors)
+- [LICENSE](#license)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
+
+
 ## Installation
 
 This module is distributed via [npm][npm] which is bundled with [node][node] and
@@ -82,7 +102,10 @@ function identifierReversePlugin() {
     name: 'identifier reverse',
     visitor: {
       Identifier(idPath) {
-        idPath.node.name = idPath.node.name.split('').reverse().join('')
+        idPath.node.name = idPath.node.name
+          .split('')
+          .reverse()
+          .join('')
       },
     },
   }
@@ -428,7 +451,7 @@ pluginTester({
 
 I've been thinking about this for a while. The API was inspired by:
 
-- ESLint's [RuleTester][RuleTester]
+- ESLint's [RuleTester][ruletester]
 - [@thejameskyle][@thejameskyle]'s [tweet][jamestweet]
 
 ## Other Solutions
@@ -440,8 +463,10 @@ I've been thinking about this for a while. The API was inspired by:
 Thanks goes to these people ([emoji key][emojis]):
 
 <!-- ALL-CONTRIBUTORS-LIST:START - Do not remove or modify this section -->
-| [<img src="https://avatars.githubusercontent.com/u/1500684?v=3" width="100px;"/><br /><sub>Kent C. Dodds</sub>](https://kentcdodds.com)<br />[💻](https://github.com/babel-utils/babel-plugin-tester/commits?author=kentcdodds "Code") [📖](https://github.com/babel-utils/babel-plugin-tester/commits?author=kentcdodds "Documentation") [🚇](#infra-kentcdodds "Infrastructure (Hosting, Build-Tools, etc)") [⚠️](https://github.com/babel-utils/babel-plugin-tester/commits?author=kentcdodds "Tests") | [<img src="https://avatars3.githubusercontent.com/u/952783?v=3" width="100px;"/><br /><sub>james kyle</sub>](http://thejameskyle.com/)<br />[💻](https://github.com/babel-utils/babel-plugin-tester/commits?author=thejameskyle "Code") [📖](https://github.com/babel-utils/babel-plugin-tester/commits?author=thejameskyle "Documentation") [👀](#review-thejameskyle "Reviewed Pull Requests") [⚠️](https://github.com/babel-utils/babel-plugin-tester/commits?author=thejameskyle "Tests") | [<img src="https://avatars1.githubusercontent.com/u/1894628?v=3" width="100px;"/><br /><sub>Brad Bohen</sub>](https://github.com/bbohen)<br />[🐛](https://github.com/babel-utils/babel-plugin-tester/issues?q=author%3Abbohen "Bug reports") | [<img src="https://avatars0.githubusercontent.com/u/1295580?v=3" width="100px;"/><br /><sub>Kyle Welch</sub>](http://www.krwelch.com)<br />[💻](https://github.com/babel-utils/babel-plugin-tester/commits?author=kwelch "Code") [📖](https://github.com/babel-utils/babel-plugin-tester/commits?author=kwelch "Documentation") [⚠️](https://github.com/babel-utils/babel-plugin-tester/commits?author=kwelch "Tests") |
-| :---: | :---: | :---: | :---: |
+<!-- prettier-ignore -->
+| [<img src="https://avatars.githubusercontent.com/u/1500684?v=3" width="100px;"/><br /><sub><b>Kent C. Dodds</b></sub>](https://kentcdodds.com)<br />[💻](https://github.com/babel-utils/babel-plugin-tester/commits?author=kentcdodds "Code") [📖](https://github.com/babel-utils/babel-plugin-tester/commits?author=kentcdodds "Documentation") [🚇](#infra-kentcdodds "Infrastructure (Hosting, Build-Tools, etc)") [⚠️](https://github.com/babel-utils/babel-plugin-tester/commits?author=kentcdodds "Tests") | [<img src="https://avatars3.githubusercontent.com/u/952783?v=3" width="100px;"/><br /><sub><b>james kyle</b></sub>](http://thejameskyle.com/)<br />[💻](https://github.com/babel-utils/babel-plugin-tester/commits?author=thejameskyle "Code") [📖](https://github.com/babel-utils/babel-plugin-tester/commits?author=thejameskyle "Documentation") [👀](#review-thejameskyle "Reviewed Pull Requests") [⚠️](https://github.com/babel-utils/babel-plugin-tester/commits?author=thejameskyle "Tests") | [<img src="https://avatars1.githubusercontent.com/u/1894628?v=3" width="100px;"/><br /><sub><b>Brad Bohen</b></sub>](https://github.com/bbohen)<br />[🐛](https://github.com/babel-utils/babel-plugin-tester/issues?q=author%3Abbohen "Bug reports") | [<img src="https://avatars0.githubusercontent.com/u/1295580?v=3" width="100px;"/><br /><sub><b>Kyle Welch</b></sub>](http://www.krwelch.com)<br />[💻](https://github.com/babel-utils/babel-plugin-tester/commits?author=kwelch "Code") [📖](https://github.com/babel-utils/babel-plugin-tester/commits?author=kwelch "Documentation") [⚠️](https://github.com/babel-utils/babel-plugin-tester/commits?author=kwelch "Tests") | [<img src="https://avatars3.githubusercontent.com/u/6680299?v=4" width="100px;"/><br /><sub><b>kontrollanten</b></sub>](https://github.com/kontrollanten)<br />[💻](https://github.com/babel-utils/babel-plugin-tester/commits?author=kontrollanten "Code") |
+| :---: | :---: | :---: | :---: | :---: |
+
 <!-- ALL-CONTRIBUTORS-LIST:END -->
 
 This project follows the [all-contributors][all-contributors] specification.
@@ -484,7 +509,7 @@ MIT
 [emojis]: https://github.com/kentcdodds/all-contributors#emoji-key
 [all-contributors]: https://github.com/kentcdodds/all-contributors
 [lodash.merge]: https://lodash.com/docs/4.17.4#merge
-[RuleTester]: http://eslint.org/docs/developer-guide/working-with-rules#rule-unit-tests
+[ruletester]: http://eslint.org/docs/developer-guide/working-with-rules#rule-unit-tests
 [@thejameskyle]: https://github.com/thejameskyle
 [jamestweet]: https://twitter.com/thejameskyle/status/864359438819262465
 [@babel/helper-plugin-test-runner]: https://github.com/babel/babel/tree/master/packages/babel-helper-plugin-test-runner

package.json

@@ -36,15 +36,20 @@
     "babel-plugin-transform-async-to-generator": "^6.24.1",
     "babel-plugin-transform-object-rest-spread": "^6.26.0",
     "babel-preset-env": "^1.5.2",
-    "kcd-scripts": "^0.16.3"
+    "kcd-scripts": "^0.42.1"
   },
   "peerDependencies": {
     "babel-core": "^6.0.0 || ^7.0.0-alpha || ^7.0.0-beta || ^7.0.0"
   },
   "eslintConfig": {
     "extends": "./node_modules/kcd-scripts/eslint.js",
     "rules": {
-      "max-lines": 0
+      "jest/valid-describe": 0,
+      "max-lines": 0,
+      "semi": [
+        2,
+        "never"
+      ]
     }
   },
   "eslintIgnore": [

src/__tests__/__snapshots__/index.js.snap

@@ -1,6 +1,14 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`1. captains-log 1`] = `
+exports[`can fail tests in fixtures at an absolute path 1`] = `"actual output does not match output.js"`;
+
+exports[`default will throw if output changes 1`] = `"Expected output to not change, but it did"`;
+
+exports[`plugin is required 1`] = `"plugin is a required parameter."`;
+
+exports[`snapshot option can be derived from the root config 1`] = `"\`output\` cannot be provided with \`snapshot: true\`"`;
+
+exports[`takes a snapshot: 1. captains-log 1`] = `
 "
 var hi = \\"hey\\";
 
@@ -10,14 +18,6 @@ var ih = \\"hey\\";
 "
 `;
 
-exports[`can fail tests in fixtures at an absolute path 1`] = `"actual output does not match output.js"`;
-
-exports[`default will throw if output changes 1`] = `"Expected output to not change, but it did"`;
-
-exports[`plugin is required 1`] = `"plugin is a required parameter."`;
-
-exports[`snapshot option can be derived from the root config 1`] = `"\`output\` cannot be provided with \`snapshot: true\`"`;
-
 exports[`tests cannot be both only-ed and skipped 1`] = `"Cannot enable both skip and only on a test"`;
 
 exports[`throws an error if babelrc is true with no filename 1`] = `"babelrc set to true, but no filename specified in babelOptions"`;

src/__tests__/index.js

@@ -189,6 +189,36 @@ test('trims and deindents code and output', async () => {
   )
 })
 
+test('accepts an empty output', async () => {
+  const tests = [
+    {
+      code: `var eraseMe = 'junk'`,
+      output: '',
+    },
+  ]
+  let errorResponse
+  try {
+    await pluginTester(
+      getOptions({
+        plugin: () => ({
+          name: 'cleanup',
+          visitor: {
+            VariableDeclaration(p) {
+              p.remove()
+            },
+          },
+        }),
+        tests,
+      }),
+    )
+    errorResponse = false
+  } catch (error) {
+    errorResponse = true
+  }
+
+  expect(errorResponse).toEqual(false)
+})
+
 test('can get a code and output fixture that is an absolute path', async () => {
   const tests = [
     {

src/index.js

@@ -19,6 +19,7 @@ const fullDefaultConfig = {
   },
 }
 
+// eslint-disable-next-line max-lines-per-function
 function pluginTester({
   /* istanbul ignore next (TODO: write a test for this) */
   babel = require('babel-core'),
@@ -163,7 +164,7 @@ function pluginTester({
           expect(`\n${formattedOutput}\n`).toMatchSnapshot(title)
         } else if (error) {
           assertError(result, error)
-        } else if (output) {
+        } else if (typeof output === 'string') {
           assert.equal(result, output, 'Output is incorrect.')
         } else {
           assert.equal(
@@ -187,7 +188,7 @@ function pluginTester({
       fixture,
       code = getCode(filename, fixture),
       fullTitle = title || `${testNumber++}. ${pluginName}`,
-      output = getCode(filename, testConfig.outputFixture),
+      output = getCode(filename, testConfig.outputFixture) || undefined,
       pluginOptions: testOptions = pluginOptions,
     } = testConfig
     return merge(
@@ -199,7 +200,7 @@ function pluginTester({
         babelOptions: {plugins: [[plugin, testOptions]]},
         title: fullTitle,
         code: stripIndent(code).trim(),
-        output: stripIndent(output).trim(),
+        ...(output ? {output: stripIndent(output).trim()} : {}),
       },
     )
   }