Add new exercise grep

[TomPradat]

Fixes #737 .

I was wondering about the fact that this exercise is a CLI.

Unless I missed something, it's not possible to test a file that just executes a set of instructions.

I was thinking about exporting a function that takes the pattern, the files and options as arguments like that :

export default (pattern, files, options =  {}) => {}

Is the user supposed to use the filesystem or should I provide him the data in the files in some way ?

[SleeplessByte]

Great question. From the canonical data:

    " The language track implementing this exercise       ",
    " should ensure that when the tests run, three files  ",
    " are created with the following contents. The file   ",
    " names and their contents are listed below:          ",

I think we should actually create these files, instead of having them be generated by the tests. So, add iliad.txt, midsummer-night.txt and paradise-lost.txt as files to the exercise directory grep (these will be downloaded automagically when using the exercism cli!)

For your second question, let's see if @tejasbubane agrees with this, I actually think it would be great if you make this script executable. That means, NO EXPORTS. I think we should do spawn or spawnSync and execute node on the file, with actual arguments, and use stdout for parsing. This exercise a the perfect opportunity to learn about:

• process.args / process.argv0
• process.stdout / process.stderr
• path
• fs

Example:

describe("tests something", () => {
  it("works", () => {
    const output = spawnSync('node', ['grep.js', '"Agamemnon"', 'iliad.txt'], { stdio: 'pipe' }).stdout.toString().trim()
    expect(output).toBe("Of Atreus, Agamemnon, King of men.")
  })
})

Stub

Add the hashbang at the top so people can actually execute it on UNIX/POSIX environments:

#!/usr/bin/env node

We can even debate adding a "cross env" wrapper grep.sh and grep.bat, but that is to be seen.

[TomPradat]

Alright, I didn't know about spawSync, I agree this is a great opportunity to learn more about nodejs, I'll go on this 👍

[TomPradat]

The MVP is working, i'll finish this ASAP :)

[TomPradat]

So i got a problem because the test script only copies the example.js and the spec file, which causes the script to fail because the .txt files are not copied

[SleeplessByte]

So i got a problem because the test script only copies the example.js and the spec file, which causes the script to fail because the .txt files are not copied

Yes! Let's add them.

If you look at this code: https://github.com/exercism/javascript/blob/master/scripts/helpers.js#L74-L77

  const libDir = ['exercises', assignment, 'lib'].join('/');
  if(shell.test('-d', libDir)) {
    shell.cp(libDir + '/*.js', 'tmp_exercises/lib');
  }

... you can see the lib dir is being copied, as long as it ends on .js. Let's add a data folder, where we copy anything:

  const dataDir = ['exercises', assignment, 'data'].join('/');
  if(shell.test('-d', dataDir)) {
    shell.cp([dataDir, '*'].join('/'), 'tmp_exercises/data');
  }

[TomPradat]

So i got a problem because the test script only copies the example.js and the spec file, which causes the script to fail because the .txt files are not copied

Yes! Let's add them.

If you look at this code: https://github.com/exercism/javascript/blob/master/scripts/helpers.js#L74-L77

  const libDir = ['exercises', assignment, 'lib'].join('/');
  if(shell.test('-d', libDir)) {
    shell.cp(libDir + '/*.js', 'tmp_exercises/lib');
  }

... you can see the lib dir is being copied, as long as it ends on .js. Let's add a data folder, where we copy anything:

  const dataDir = ['exercises', assignment, 'data'].join('/');
  if(shell.test('-d', dataDir)) {
    shell.cp([dataDir, '*'].join('/'), 'tmp_exercises/data');
  }

Nice, should I add it myself ?

[SleeplessByte]

Yes go ahead!

[TomPradat]

Should I add stuff in the stub file ? Or should we let the user do the exercise from scratch ?

Also should I write a README.md ?

[SleeplessByte]

See CONTRIBUTING for the readme generation. You don't need to do this yourself.

Let's add the stub file, but only have a comment with 'this is a stub blablabla'

[TomPradat]

If everything is ok, i can rebase my last 3 commits and we can merge this :)

[SleeplessByte]

You don't need to rebase. I'll squash-merge

[TomPradat]

Hi, do you have some time to merge it ?

[TomPradat]

This should be good now I think

[Calamari]

I like this exercise, I think it would make a great addition to explore JS more.

[SleeplessByte]

I absolutely love this exercise. Thank you so much for writing this @TomPradat