A simple and pragmatic library for testing Node.js console output.
npm install test-consoleA simple and pragmatic library for testing Node.js console output.
See the API section for more examples.
``javascript
const stdout = require("test-console").stdout;
const output = stdout.inspectSync(() => {
console.log("foo");
});
assert.deepEqual(output, [ "foo\n "]);
`
This is a Node.js library. Install Node, then:
npm install test-console (add --save or --save-dev if you want)
To use the library in your code, require it as follows:
`javascript`
const stdout = require("test-console").stdout;
const stderr = require("test-console").stderr;
* stdout.inspect: Redirects writes to stdout into an array instead of writing them to console.stdout.inspectSync
* : Just like inspect(), but automatically restores the console when done.stdout.inspectAsync
* : Just like inspectSync(), but works with async functions.stdout.ignore
* : Prevent writes to stdout from appearing on the console.stdout.ignoreSync
* : Just like ignore(), but automatically restores the console when done.stdout.ignoreAsync
* : Just like ignoreSync(), but works with async functions.
All functions accept an optional options object as the first argument, where isTTY is the only available option. isTTY, if defined, will override the stdout field of the same name.
The same API is also available on stderr.
Redirects writes to stdout into an array instead of writing them to the console.
* options: object [optional]isTTY
* : If not undefined, this value will be used to temporarily overwrite stdout.isTTY.
* inspect: Returned as an EventEmitter with two properties and one event:inspect.output
* : An array containing one string for each call to stdout.write(). This array updates every time another call to stdout.write() is made.inspect.restore()
* : Call this function to restore stdout.write() to its normal behavior.data
* event: This event fires every time stdout.write() is called.
Example of using inspect() to test a synchronous function:
`javascript`
const inspect = stdout.inspect();
functionUnderTest();
inspect.restore();
assert.deepEqual(inspect.output, [ "foo\n" ]);
Example of using inspect() to test an asynchronous function with await:
`javascript`
const inspect = stdout.inspect();
await functionUnderTestAsync();
inspect.restore();
assert.deepEqual(inspect.output, [ "foo\n" ]);
Example of using inspect() to test an asynchronous function with a callback:
`javascript`
const inspect = stdout.inspect();
functionUnderTest(() => {
inspect.restore();
assert.deepEqual(inspect.output, [ "foo\n" ]);
});
Example of using inspect() to listen for an event:
`javascript`
const inspect = stdout.inspect();
let output = "";
inspect.on("data", (chunk) => {
output += chunk;
});
functionUnderTestAsync();
inspect.restore();
assert.equal(output, "foo\n");
Just like inspect(), but automatically restores the console when done.
* options: object [optional]isTTY
* : If not undefined, this value will be used to temporarily overwrite stdout.isTTY.
* fn(output): The function to run while inspecting stdout. After the function returns, stdout.write is automatically restored. Note that output is passed into this function in addition to being returned from inspectSync().
* output: Passed into fn and also returned as an array. Contains one string for each call to stdout.write(). This array updates every time another call to stdout.write() is made.
Example of using inspectSync() to test a synchronous function:
`javascript`
const output = stdout.inspectSync(() => {
functionUnderTest();
});
assert.deepEqual(output, [ "foo\n" ]);
Example of using inspectSync() to incrementally test several synchronous functions:
``javascript`
stdout.inspectSync((output) => {
functionUnderTest();
assert.deepEqual(output, [ "foo\n" ]);
anotherFunctionUnderTest();
assert.deepEqual(output, [ "foo\n", "bar\n" ]);
});
Just like inspectSync(), but works with asynchronous functions.
* options: object [optional]isTTY
* : If not undefined, this value will be used to temporarily overwrite stdout.isTTY.
* fnAsync(output): The function to run while inspecting stdout. After the function returns, stdout.write is automatically restored. Note that output is passed into this function in addition to being returned from inspectSync().
* output: Passed into fnAsync and also returned as an array containing one string for each call to stdout.write(). This array updates every time another call to stdout.write() is made.
Example of using inspectAsync() to test an asynchronous function:
`javascript`
const output = await stdout.inspectAsync(async () => {
await functionUnderTestAsync();
});
assert.deepEqual(output, [ "foo\n" ]);
Example of using inspectAsync() to incrementally test several asynchronous functions:
``javascript`
await stdout.inspectAsync(async (output) => {
await functionUnderTestAsync();
assert.deepEqual(output, [ "foo\n" ]);
await anotherFunctionUnderTestAsync();
assert.deepEqual(output, [ "foo\n", "bar\n" ]);
});
Prevent writes to stdout from appearing on the console.
* options: object [optional]isTTY
* : If not undefined, this value will be used to temporarily overwrite stdout.isTTY
* restore(): Call this function to restore stdout.write to its normal behavior.
Example of using ignore() to prevent a synchronous function from writing to the console:
`javascript`
const restore = stdout.ignore();
functionUnderTest();
restore();
Example of using ignore() to prevent an asynchronous function with a callback from writing to the console:
`javascript`
const restore = stdout.ignore();
functionUnderTest(() => {
restore();
});
Example of using ignore() to prevent a suite of tests from writing to the console:
`javascript
let restoreStdout;
beforeEach(() => {
restoreStdout = stdout.ignore();
});
afterEach(() => {
restoreStdout();
});
// tests go here
`
Just like ignore(), but automatically restores the console when done.
* options: object [optional]isTTY
* : If not undefined, this value will be used to temporarily overwrite stdout.isTTY
* fn(): The function to run while ignoring stdout. After the function returns, stdout.write is automatically restored.
Example of using ignoreSync() to prevent a synchronous function from writing to the console:
`javascript`
stdout.ignoreSync(() => {
functionUnderTest();
});
Just like ignoreSync(), but works with async/await.
* options: object [optional]isTTY
* : If not undefined, this value will be used to temporarily overwrite stdout.isTTY
* fnAsync(): The function to run while ignoring stdout. After the function returns, stdout.write is automatically restored.
Example of using ignoreSync() to prevent an asynchronous function from writing to the console:
`javascript`
await stdout.ignoreAsync(async () => {
await functionUnderTestAsync();
});
__2.0.0:__ Add events to inspect(). Add inspectAsync(), ignoreAsync(). BREAKING CHANGE: Requires Node 7.6.0 or higher (due to async/await support)
__1.1.0:__ Add ability to override stdout.isTTY (and stderr.isTTY).
__1.0.0:__ API fails with nice error messages when called with wrong number of arguments.
__0.7.1:__ Bug fix: Sync() versions restore old behavior even if exception occurs
__0.7.0:__ Initial release: inspect(), inspectSync(), ignore(), and ignoreSync()
Created by James Shore. Inspired by Brandon Satrom's Automated Testing of Standard Output in Node.js.
Option for mocking isTTY added by Jason Boileau.
Inspect data event added by Tim Toohey.
1. Update version history in readme
2. Ensure clean build: ./jake.sh
3. Update npm version:
4. Release to npm:
5. Release to github:
The MIT License (MIT)
Copyright (c) 2014-2015 James Shore
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