feat(cli): generate changelog

.editorconfig

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+root = true
+
+[*]
+indent_style = space
+indent_size = 2
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true

.eslintignore

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+coverage/

.eslintrc

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+{
+  extends: "eslint-config-lob"
+}

.npmignore

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+test/

.travis.yml

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+language: node_js
+sudo: false
+node_js:
+  - '0.10'
+  - '0.12'
+  - '4'
+  - '5'
+after_script:
+  - npm run lint
+  - npm run enforce
+  - npm run coveralls

CONTRIBUTING.md

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+# Contributing
+
+We encourage any form of contribution, whether that be issues, comments, or pull requests. If you are going to be submitting a PR, there are a few things we would appreciate that you do to keep the codebase clean:
+
+* **Write tests.** We enforce 100% code coverage on this repo so any new code that gets written should have accompanying tests.
+* **Follow the linter.** We use our [ESLint configuration](https://github.com/lob/eslint-config-lob), and we run `npm run lint` in our Travis builds.
+* **Ask questions if you aren't sure.** If you have any questions while implementing a fix or feature, feel free to create an issue and ask us. We're happy to help!

README.md

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 # Generate Changelog
 
+[![Build Status](https://travis-ci.org/lob/generate-changelog.svg)](https://travis-ci.org/lob/generate-changelog)
+[![Coverage Status](https://coveralls.io/repos/lob/generate-changelog/badge.svg?branch=master&service=github)](https://coveralls.io/github/lob/generate-changelog?branch=master)
+
 Generate a changelog from git commits. This is meant to be used so that for every patch, minor, or major version, you update the changelog, run `npm version`, and then the git tag refers to the commit that updated both the changelog and version.
+
+## Installation
+
+You can either install this module globally to be used for all of your repos on your local machine, or you can install it as a dev dependency to be referenced in your npm scripts.
+
+```bash
+$ npm i generate-changelog -g # install it globally
+# OR
+$ npm i generate-changelog -D # install it as a dev dependency
+```
+
+## Usage
+
+To use this module, your commit messages have to be in this format:
+
+```
+type(category): description
+```
+
+Where `type` is one of the following:
+
+* `chore`
+* `docs`
+* `feat`
+* `fix`
+* `refactor`
+* `style`
+* `test`
+
+And `category` can be anything of your choice.
+
+You can either run this module as a CLI app that prints to stdout (recommended):
+
+```bash
+$ changelog -h
+
+
+  Usage: generate [options]
+
+  Generate a changelog from git commits.
+
+  Options:
+
+    -h, --help            output usage information
+    -V, --version         output the version number
+    -p, --patch           create a patch changelog
+    -m, --minor           create a minor changelog
+    -M, --major           create a major changelog
+    -u, --repo-url [url]  specify the repo URL for commit links
+
+```
+
+Or you can write a script that calls the `generate` function:
+
+```js
+var Changelog = require('generate-changelog');
+var File      = require('fs');
+
+return Changelog.generate({ patch: true, repoUrl: 'https://github.com/lob/generate-changelog' })
+.then(function (changelog) {
+  File.writeFileSync('./CHANGELOG.md', changelog);
+});
+```
+
+### Recommended
+
+The way that I would recommend using this module would be the way it's being used in this module: as npm scripts. You should install it as a dev dependency and then add the following to the `scripts` object in your `package.json`:
+
+```json
+    "changelog:major": "./bin/generate -M >> CHANGELOG.md && git commit -am 'updated CHANGELOG.md' && npm version major && git push origin && git push origin --tags",
+    "changelog:minor": "./bin/generate -m >> CHANGELOG.md && git commit -am 'updated CHANGELOG.md' && npm version minor && git push origin && git push origin --tags",
+    "changelog:patch": "./bin/generate -p >> CHANGELOG.md && git commit -am 'updated CHANGELOG.md' && npm version patch && git push origin && git push origin --tags",
+```
+
+## Testing
+
+To run the test suite, just clone the repository and run the following:
+
+```bash
+$ npm i
+$ npm test
+```
+
+## Contributing
+
+To contribute, please see the [CONTRIBUTING.md](CONTRIBUTING.md) file.
+
+## License
+
+This project is released under the MIT license, which can be found in [`LICENSE.txt`](LICENSE.txt).

bin/generate

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+#!/usr/bin/env node
+'use strict';
+
+var CLI       = require('../lib/cli');
+var Changelog = require('../lib');
+
+CLI.parse(process.argv);
+
+return Changelog.generate(CLI)
+.then(function (changelog) {
+  console.log(changelog);
+})
+.catch(function (err) {
+  console.log(err);
+});

lib/cli.js

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+'use strict';
+
+var CLI = require('commander');
+
+var Package = require('../package');
+
+module.exports = CLI
+  .description('Generate a changelog from git commits.')
+  .version(Package.version)
+  .option('-p, --patch', 'create a patch changelog')
+  .option('-m, --minor', 'create a minor changelog')
+  .option('-M, --major', 'create a major changelog')
+  .option('-u, --repo-url [url]', 'specify the repo URL for commit links');

lib/git.js

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+'use strict';
+
+var Bluebird = require('bluebird');
+var CP       = Bluebird.promisifyAll(require('child_process'));
+
+var SEPARATOR      = '===END===';
+var COMMIT_PATTERN = /^(\w*)(\(([\w\$\.\-\* ]*)\))?\: (.*)$/;
+var FORMAT         = '%H%n%s%n%b%n' + SEPARATOR;
+
+/**
+ * Get all commits from the last tag (or the first commit if no tags).
+ * @returns {Promise<Array<Object>>} array of parsed commit objects
+ */
+exports.getCommits = function () {
+  return CP.execAsync('git describe --tags --abbrev=0')
+  .catch(function () {
+    return '';
+  })
+  .then(function (tag) {
+    tag = tag.toString().trim();
+    var revisions = tag ? tag + '..HEAD' : '';
+
+    return CP.execAsync('git log -E --format=' + FORMAT + ' ' + revisions);
+  })
+  .catch(function () {
+    throw new Error('no commits found');
+  })
+  .then(function (commits) {
+    return commits.split('\n' + SEPARATOR + '\n');
+  })
+  .map(function (raw) {
+    if (!raw) {
+      return null;
+    }
+
+    var lines = raw.split('\n');
+    var commit = {};
+
+    commit.hash = lines.shift();
+    commit.subject = lines.shift();
+    commit.body = lines.join('\n');
+
+    var parsed = commit.subject.match(COMMIT_PATTERN);
+
+    if (!parsed || !parsed[1] || !parsed[4]) {
+      return null;
+    }
+
+    commit.type = parsed[1];
+    commit.category = parsed[3];
+    commit.subject = parsed[4];
+
+    return commit;
+  })
+  .filter(function (commit) {
+    return commit !== null;
+  });
+};

lib/index.js

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+'use strict';
+
+var Bluebird = require('bluebird');
+
+var Git     = require('./git');
+var Package = require('./package');
+var Writer  = require('./writer');
+
+/**
+ * Generate the changelog.
+ * @param {Object} options - generation options
+ * @param {Boolean} options.patch - whether it should be a patch changelog
+ * @param {Boolean} options.minor - whether it should be a minor changelog
+ * @param {Boolean} options.major - whether it should be a major changelog
+ * @param {String} options.repoUrl - repo URL that will be used when linking commits
+ * @returns {Promise<String>} the \n separated changelog string
+ */
+exports.generate = function (options) {
+  return Bluebird.all([
+    Package.extractRepoUrl(),
+    Package.calculateNewVersion(options),
+    Git.getCommits()
+  ])
+  .spread(function (repoUrl, version, commits) {
+    options.repoUrl = options.repoUrl || repoUrl;
+
+    return Writer.markdown(version, commits, options);
+  });
+};

lib/package.js

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+'use strict';
+
+var Bluebird       = require('bluebird');
+var File           = Bluebird.promisifyAll(require('fs'));
+var ParseGitHubUrl = require('github-url-from-git');
+
+/**
+ * Get the package.json object located in the current directory.
+ * @returns {Promise<Object>} package.json object
+ */
+exports.getUserPackage = function () {
+  var userPackagePath = process.cwd() + '/package.json';
+
+  return File.statAsync(userPackagePath)
+  .then(function () {
+    return require(userPackagePath);
+  })
+  .catch(function () {
+    throw new Error('valid package.json not found');
+  });
+};
+
+/**
+ * Grabs the repository URL if it exists in the package.json.
+ * @returns {Promise<String|Null>} the repository URL or null if it doesn't exist
+ */
+exports.extractRepoUrl = function () {
+  return exports.getUserPackage()
+  .then(function (userPackage) {
+    var url = userPackage.repository && userPackage.repository.url;
+
+    if (typeof url !== 'string') {
+      return null;
+    }
+
+    if (url.indexOf('github') === -1) {
+      return url;
+    } else {
+      return ParseGitHubUrl(url);
+    }
+  });
+};
+
+/**
+ * Calculate the new semver version depending on the options.
+ * @param {Object} options - calculation options
+ * @param {Boolean} options.patch - whether it should be a patch version
+ * @param {Boolean} options.minor - whether it should be a minor version
+ * @param {Boolean} options.major - whether it should be a major version
+ * @returns {Promise<String>} - new version
+ */
+exports.calculateNewVersion = function (options) {
+  return exports.getUserPackage()
+  .then(function (userPackage) {
+    var split = userPackage.version.split('.');
+
+    if (options.major) {
+      split[0] = (parseInt(split[0]) + 1).toString();
+      split[1] = '0';
+      split[2] = '0';
+    } else if (options.minor) {
+      split[1] = (parseInt(split[1]) + 1).toString();
+      split[2] = '0';
+    } else if (options.patch) {
+      split[2] = (parseInt(split[2]) + 1).toString();
+    } else {
+      throw new Error('patch, minor, or major needs to be set');
+    }
+
+    return split.join('.');
+  });
+};