temp-context

temp-context is a Zoroaster test context to initialise a temporary directory for each test, and remove it at the end. It also contains methods to read, write, clone, assert existence and remove files inside and outside of the temp dir.

yarn add -E temp-context

Table Of Contents

• Table Of Contents
• API
• class TempContext
  • get TEMP
  • resolve(path: string): string
  • async exists(path: string): boolean
  • async existsGlobal(path: string): boolean
  • async read(path: string): string
  • async readGlobal(path: string): string
  • async write(data: string, path: string): string
  • async add(target: string): string
  • async clone(from: string, to: boolean)
  • async rm(path: string)
  • async snapshot(innerPath?: string): string
• Example
  • Masks
  • Specs
  • Output
  • Autocompletion
• Extending
• Copyright

API

The package is available by importing its default function:

import TempContext from 'temp-context'

class TempContext

Instances of this test context class will create a temp directory in the test folder on initialisation, and remove it at the end of each test. To change the location of the test directory, extend the class.

The test context is used with the Zoroaster testing framework, which will initialise and destroy it for every test. Check the example section to see how tests are implemented.

get TEMP

Return the path to the temp folder.

resolve(
  path: string,
): string

Resolve a path inside of the temp directory, e.g., resolve('data.temp') will return test/temp/data.temp.

async exists(
  path: string,
): boolean

Check if the path exists in the temp directory.

async existsGlobal(
  path: string,
): boolean

Check if the path exists on the filesystem.

async read(
  path: string,
): string

Read the file in the temp directory and returns its contents.

async readGlobal(
  path: string,
): string

Read the file given its path and returns its contents. Alias for @wrote/read.

async write(
  data: string,
  path: string,
): string

Write to the file in the temp directory and return its path.

async add(
  target: string,
): string

Adds a file or directory to the temp directory and returns its new path.

async clone(
  from: string,
  to: boolean,
): void

Clone a file or directory to the specified location. Alias for @wrote/clone.

async rm(
  path: string,
): void

Remove a file or folder inside of the temp directory. Alias for @wrote/rm.

async snapshot(
  innerPath?: string,
): string

Takes a snapshot of the temp directory, which can then be saved and tested either with Zoroaster masks or snapshot-context.

Example

Zoroaster tests can be written either as masks, or more traditionally as specs. For example, a program might want to write given data to a file in a specified directory, as so:

import { join } from 'path'
import { createWriteStream } from 'fs'

/**
 * Writes given data to a hidden file.
 * @param {string} path Path to the directory where to create a file.
 * @param {string} data Data to write.
 */
const program = (path, data) => {
  const j = join(path, '.test')
  const rs = createWriteStream(j)
  rs.end(`hello world: ${data}`)
}

export default program

When writing tests with Zoroaster, the project directory will have the src and test directories:

example
├── src
│   └── index.js
└── test
    ├── context
    │   ├── index.js
    │   └── temp.js
    ├── mask
    │   └── default.js
    ├── result
    │   └── default.md
    └── spec
        ├── default.js
        └── extended.js

Masks

To implement tests with masks, a mask implementation should be set up in the mask directory:

import makeTestSuite from '@zoroaster/mask'
import TempContext from 'temp-context'
import program from '../../src'

/**
 * This test suite will clone an input and take a snapshot of the temp directory.
 */
export default makeTestSuite('example/test/result', {
  /**
   * @param {string} input
   * @param {TempContext} context
   */
  async getResults(input, { TEMP, snapshot }) {
    await program(TEMP, input)
    const s = await snapshot()
    return s
  },
  context: TempContext,
})

The results file which contains data about how input should be mapped to the output is saved in the results directory:

## creates a file in the temp directory
input data

/* expected */
# .test

hello world: input data
/**/

Now when run, zoroaster will use the mask test suite (generated with the makeTestSuite function) to check that inputs match expected outputs.

Specs

Occasionally, there are times when masks are not flexible enough to run tests. Specs are individual test cases, and can access test contexts assigned to the context property of a test suite.

import TempContext from 'temp-context'
import { ok, equal } from 'zoroaster/assert'
import Context from '../context'
import program from '../../src'

/** @type {Object.<string, (c:Context, tc: TempContext)>} */
const T = {
  context: [Context, TempContext],
  async 'writes data to a file'(
    { DATA }, { TEMP, resolve, exists, read },
  ) {
    await program(TEMP, DATA)
    const j = resolve('.test')
    console.log('Temp file location: %s', j)

    const e = await exists(j)
    ok(e)
    const res = await read('.test')
    equal(res, `hello world: ${DATA}`)
  },
}

export default T

Output

The outcome of all the above tests can be achieved with zoroaster -a example/test/spec example/test/mask command, where -a is used to require alamode -- a fast RegExp-based transpiler of import and export statements.

example/test/spec/default.js
Temp file location: test/temp/.test
  ✗  writes data to a file
  | AssertionError [ERR_ASSERTION]: false == true
  |     at writes data to a file (/Users/zavr/wrote/temp-context/example/test/spec/default.js:17:5)
 example/test/mask
  ✓  creates a file in the temp directory

example/test/spec/default.js > writes data to a file
  AssertionError [ERR_ASSERTION]: false == true
      at writes data to a file (/Users/zavr/wrote/temp-context/example/test/spec/default.js:17:5)

🦅  Executed 2 tests: 1 error.

Autocompletion

One of the advantages of using test context is that they are well documented and it's possible to get auto-completes for available methods when using destructuring on the context argument to a test case, both in masks as well as in specs.

Extending

Extending the TempContext allows to set the specific temp directory location, and/or add additional methods without having to have 2 contexts for testing.

import TempContext from 'temp-context'

export default class MyTempContext extends TempContext {
  constructor() {
    super()
    this._useOSTemp('package-test')
  }
  get DATA() {
    return 'test-data'
  }
}

import { ok, equal } from 'zoroaster/assert'
import MyTempContext from '../context/temp'
import program from '../../src'

/** @type {Object.<string, (tc: MyTempContext)>} */
const T = {
  context: MyTempContext,
  async 'writes data to a file'(
    { TEMP, resolve, exists, read, DATA },
  ) {
    await program(TEMP, DATA)
    const j = resolve('.test')
    console.log('Temp file location: %s', j)

    const e = await exists(j)
    ok(e)
    const res = await read('.test')
    equal(res, `hello world: ${DATA}`)
  },
}

export default T

example/test/spec/extended.js
Temp file location: /private/tmp/package-test/.test
  ✗  writes data to a file
  | AssertionError [ERR_ASSERTION]: false == true
  |     at writes data to a file (/Users/zavr/wrote/temp-context/example/test/spec/extended.js:16:5)

example/test/spec/extended.js > writes data to a file
  AssertionError [ERR_ASSERTION]: false == true
      at writes data to a file (/Users/zavr/wrote/temp-context/example/test/spec/extended.js:16:5)

🦅  Executed 1 test: 1 error.

Copyright

(c) Wrote 2019