https://github.com/martypdx/test-stdio

Simple micro-library for testing process stdin, stdout, and stderr
https://github.com/martypdx/test-stdio

Last synced: about 10 hours ago
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Simple micro-library for testing process stdin, stdout, and stderr

• Host: GitHub
• URL: https://github.com/martypdx/test-stdio
• Owner: martypdx
• Created: 2011-12-10T00:30:53.000Z (almost 13 years ago)
• Default Branch: master
• Last Pushed: 2011-12-10T23:04:29.000Z (almost 13 years ago)
• Last Synced: 2024-10-12T14:50:01.901Z (about 1 month ago)
• Homepage:
• Size: 82 KB
• Stars: 1
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# test-stdio

test-stdio is a micro-library for testing node modules that do cli and other uses of process stdin, stdout, and stderr.

## Usage

test-stdio is designed for testing node modules via require.

### stdin

`process.stdin` is mocked by calling `stdin()` which has a `write(data)` method for simulating input:

    var stdin = require('../test-stdio').stdin()

    

    var myProgram = require('myProgram')

    myProgram.runSomeFunction() 

    //myProgram now expecting user input on stdin

    

    stdin.write('hello world')

    

### stdout and stderr

`process.stdout` and `process.stderr` are mocked by calling `stdout()` and `stderr()` respectively.

Both have an `expect(expected, fn)` method that 

can be used to test std output. It takes an expected value and a function that will 

run the code that will produce the output:

    var stdout = require('../test-stdio').stdout()

    var myProgram = require('myProgram')

    

    stdout.expect('hello world', function(){

        myProgram.sayHello() //writes 'hello world' to stdout   

    })

    

`expected` can also be a function:

    stdout.expect(

        function(actual) {

            return actual === 'hello world'

        }, 

        function(){

            myProgram.sayHello()   

        }

    )

    

There is also a `log` method that can be used since `console.log` is redirected to the mock:

    stdout.log('This will not be routed back to mocked stdout')

    

### Combining stdin and stdout

These can be combine to test workflows:

    stdout.expect(prompt, function() {

        var actual

        program.prompt(prompt, Number, function(val) { 

            actual = val

        })

        

        stdout.expect(prompt + '(must be a number) ', function() {

            stdin.write('blue')    

        })

        stdout.expect(prompt + '(must be a number) ', function() {

            stdin.write('blue')

        })

        stdin.write(42)  

        assert.strictEqual(actual, 42)

    })

    

or multi-line input:

    stdout.expect(prompt + '\n', function() {

        var actual

        program.prompt(prompt, function(val) {

            actual = val

        }

        

        stdin.write('hello world\n');

        stdin.write('  and what a world\n');

        stdin.write('it could be\n');

        stdin.write('\n');

        

        assert.strictEqual(actual, 'hello world\n  and what a world\nit could be')

    })

    

### .real and revert()

Each mock also exposes a `.real` property that can be used to access the original stdio:

    var realStdout = stdout.real

Call `revert` to restore process to use original stdio:

    stdin.revert()

    

There's not currently any way to resume use of the same mock object, call .stdin() again to create a new mock.