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Introduction

Now we have learned the basics of shell scripting with node.js we can put it to practice and build our own command-line tools!

Specifically in this lesson your task is to build a test output formatter. A test output formatter is a program that when you pipe the results of your tests into, will read the results of those tests and reformat them as output. We will use tape for our tests in this exercise.

A simple example of an output formatter is tap-nyan. To install it, create a package.json using npm init, and run npm install --save-dev tap-nyan. If you call tap-nyan like so:

node test.js | tap-nyan

It will output something like this to the terminal:

13  -_-_-_-_-_-_-_,------,
0   -_-_-_-_-_-_-_|   /\_/\
0   -_-_-_-_-_-_-^|__( ^ .^)
    -_-_-_-_-_-_-  ""  ""
 Pass!

If you get an error message saying something like command tap-nyan cannot be found try running it like this instead:

node test.js | node_modules/.bin/tnyan

What's happening here?

Something like this can be implemented using what you've already learned. The command node test.js executes the test file specified and outputs the results of the tape tests to the terminal. They look like this:

TAP version 13
# Description for your test
ok 1 just testing everything works
# Simple values, number, strings, booleans
ok 2 should be equal
ok 3 should be equal
ok 4 should be equal
# Complex values - objects and arrays
ok 5 should be equivalent
ok 6 should be equivalent
# Truthy and falsy
ok 7 should be truthy
ok 8 should be falsy
ok 9 should be falsy
# Async testing
ok 10 should be equal
ok 11 should be equal
# Error handling
ok 12 should throw
ok 13 should be equal

1..13
# tests 13
# pass  13

# ok

Using the | command this output then becomes the input of tap-nyan. Remember we can access piped in input, as a read stream, in our node programs using the process.openStdin() method.

Then all the program is doing is reading the outputs of these tests, tallying how many pass or fail, and logging pass! if they all pass along with a cute ascii image.

Try making some tests fail and seeing what tap-nyan responds with instead:

12  -_-_-_-_-_-_-_,------,
1   -_-_-_-_-_-_-_|   /\_/\
0   -_-_-_-_-_-_-^|__( x .x)
    -_-_-_-_-_-_-  ""  ""
 Failed Tests: There was 1 failure

   ✗ Async testing: should be equal

The image changes, it tallies the number of failing tests, and lets you know which tests failed.

Task

Make your own output formatter! You can make it simple, like tap-nyan, or as complex as you like (how about piping the results of multiple test files into it?). The primary aim is just to have fun and be creative.

I would recommend just starting out printing two numbers to the terminal, one being how many of the tests passed, the other how many of the tests failed. You can build on this to print 'pass!' if all tests pass and 'fail!' if any test failed. Then add-in your own styles, and features.

Clone this repo and go into the project folder to find an example tape test file you can use. You'll need to create a package.json and install tape.

Your output formatter should be implemented like so:

node test.js | node output-formatter.js

or, if you make it executable (follow the instructions in LESSON1.md to do this):

node test.js | output-formatter

The only program you need to write is output-formatter.js, however feel free to modularise and write tests for the code if it becomes appropriate.

Colours and styling

If you want to add colours and stylings to what you output to the terminal, the manual way of doing it is to add escape sequences to your console.log() like so:

console.log('\x1b[36m]', 'sometext'); // 'sometext's colour will be modified

The easier way to do it is to use a third-party module like colors or chalk which abstracts this for you. Go to their github repo's to find instructions on how to use and install them.

chalk: https://github.com/chalk/chalk

colors: https://www.npmjs.com/package/colors

Publishing to npm

Now we have created our own command-line tool, we have in effect created our own node module we can publish to the npm registry that others can install and use!

Please first use the instructions in LESSON1.md to make your script node output-formatter.js globally executable.

Creating a user

You can publish any directory to npm that has a package.json.

To publish, you must have a user on the npm registry. If you don't have one, you can create one with the command npm adduser. If you created one on the npm site, use npm login to store the credentials on the client.

You can use npm config ls to ensure that the credentials are stored on your client. Check that it has been added to the registry by going to https://npmjs.com/~.

Publishing your package

Note: The following is here for educational purposes. It's advisable to not be too frivolous in publishing to npm. If you do, be sure to provide ample documentation for your project on your repository and on npm.

Use npm publish to publish the package! That's it!

Note that everything in the directory will be included unless it is ignored by a local .gitignore or .npmignore file.

Also make sure there isn't already a package with the same name, owned by somebody else.

If you want to test this has worked go to https://npmjs.com/package/. You should see the information for your new package.

If you then want someone to install your new module onto their machine, try out:

npm install -g name-of-your-package

: - )