Express Butterfly Effect 🦋🌊

Descirption

When a butterfly flaps its wings over some line of your code there is was no telling of the consequence.

express-butterfly-effect takes one or more file changes and gives you back which express endpoints might be affected by those changes

Installation

npm i --save-dev express-butterfly-effect

Usage

You can either use express-butterfly-effect as a command-line app or as a library.

As a command-line app you would do:

./node_modules/.bin/express-butterfly-effect glob1 [glob2] change1 [change2]

You need to specify at least one glob and one change. Globs are used to find all the .js files in your project.

A change is a path to a file, followed by a : and then a line number or line range (start-count), possibly followed by other : plus line or range.

For example:

./node_modules/.bin/express-butterfly-effect './lib/**/*.js' \
  ./lib/my-file.js:1:4-2:10 \
  ./lib/my-other-file.js:5

# my-file.js changed at lines 1, 4, 5 and 10
# my-other-file.js changed at line 5

To use express-butterfly-effect you need to:

const computeEndpointImpact = require('express-butterfly-effect').default;
// Note: .default in the line above!

const impact = computeEndpointImpact(
  globs, // string[],
  targetFiles, // string[]
);

// impact is a string[], where each item looks like:
// 'get /api/users/1' (i.e. method + ' ' +  path)

Pulling changes from git

./node_modules/express-butterfly-effect/git-changes.sh [base-branch]

If you omit base-branch, the script defaults to master. This script returns the changes in the format you need to pass to express-butterfly-effect.

All together it would look something like:

./node_modules/.bin/express-butterfly-effect \
  './lib/**/*.js' \
  $(./node_modules/express-butterfly-effect/git-changes.sh)