Merge pull request #141 from probot/read-config

Add helper for loading config from a repository

docs/best-practices.md

@@ -57,6 +57,4 @@ Plugins _should_ allow all settings to customized for each installation.
 
 ### Store configuration in the repository
 
-Any configuration _should_ be stored in the repository. Unless the plugin is using files from an established convention, the configuration _should_ be stored in the `.github` directory.
-
-For example, the [owners](https://github.com/probot/owners) plugin reads from the `OWNERS` file, which is a convention that existed before the plugin was created, while the [configurer](https://github.com/probot/configurer) plugin reads from `.github/config.yml`.
+Any configuration _should_ be stored in the repository. Unless the plugin is using files from an established convention, the configuration _should_ be stored in the `.github` directory. See the [API docs for `context.config`](https://probot.github.io/probot/latest/Context.html#config).

lib/context.js

@@ -1,3 +1,6 @@
+const path = require('path');
+const yaml = require('js-yaml');
+
 /**
  * Helpers for extracting information from the webhook event, which can be
  * passed to GitHub API calls.
@@ -58,6 +61,28 @@ class Context {
   get isBot() {
     return this.payload.sender.type === 'Bot';
   }
+
+  /**
+   * Reads the plugin configuration from the given YAML file in the `.github`
+   * directory of the repository.
+   *
+   * @example
+   *
+    // Load config from .github/myplugin.yml in the repository
+    const config = await context.config('myplugin.yml');
+
+    if(config.close) {
+      context.github.issues.edit(context.issue({state: 'closed'}));
+    }
+   *
+   * @param {string} fileName Name of the YAML file in the `.github` directory
+   * @return {Promise<Object>} Configuration object read from the file
+   */
+  async config(fileName) {
+    const params = this.repo({path: path.join('.github', fileName)});
+    const res = await this.github.repos.getContent(params);
+    return yaml.safeLoad(Buffer.from(res.data.content, 'base64').toString()) || {};
+  }
 }
 
 module.exports = Context;

package.json

@@ -25,6 +25,7 @@
     "github": "^9.2.0",
     "github-app": "^3.0.0",
     "github-webhook-handler": "^0.6.0",
+    "js-yaml": "^3.8.4",
     "load-plugins": "^2.1.2",
     "pkg-conf": "^2.0.0",
     "promise-events": "^0.1.3",

test/context.js

@@ -1,3 +1,5 @@
+const fs = require('fs');
+const path = require('path');
 const expect = require('expect');
 const Context = require('../lib/context');
 
@@ -67,4 +69,96 @@ describe('Context', function () {
       });
     });
   });
+
+  describe('config', function () {
+    let github;
+
+    function readConfig(fileName) {
+      const configPath = path.join(__dirname, 'fixtures', 'config', fileName);
+      const content = fs.readFileSync(configPath, {encoding: 'utf8'});
+      return {data: {content: Buffer.from(content).toString('base64')}};
+    }
+
+    beforeEach(function () {
+      github = {
+        repos: {
+          getContent: expect.createSpy()
+        }
+      };
+
+      context = new Context(event, github);
+    });
+
+    it('gets a valid configuration', async function () {
+      github.repos.getContent.andReturn(Promise.resolve(readConfig('basic.yml')));
+      const config = await context.config('test-file.yml');
+
+      expect(github.repos.getContent).toHaveBeenCalledWith({
+        owner: 'bkeepers',
+        repo: 'probot',
+        path: '.github/test-file.yml'
+      });
+      expect(config).toEqual({
+        foo: 5,
+        bar: 7,
+        baz: 11
+      });
+    });
+
+    it('throws when the file is missing', async function () {
+      github.repos.getContent.andReturn(Promise.reject(new Error('An error occurred')));
+
+      let e;
+      let contents;
+      try {
+        contents = await context.config('test-file.yml');
+      } catch (err) {
+        e = err;
+      }
+
+      expect(contents).toNotExist();
+      expect(e).toExist();
+      expect(e.message).toEqual('An error occurred');
+    });
+
+    it('throws when the configuration file is malformed', async function () {
+      github.repos.getContent.andReturn(Promise.resolve(readConfig('malformed.yml')));
+
+      let e;
+      let contents;
+      try {
+        contents = await context.config('test-file.yml');
+      } catch (err) {
+        e = err;
+      }
+
+      expect(contents).toNotExist();
+      expect(e).toExist();
+      expect(e.message).toMatch(/^end of the stream or a document separator/);
+    });
+
+    it('throws when loading unsafe yaml', async function () {
+      github.repos.getContent.andReturn(readConfig('evil.yml'));
+
+      let e;
+      let config;
+      try {
+        config = await context.config('evil.yml');
+      } catch (err) {
+        e = err;
+      }
+
+      expect(config).toNotExist();
+      expect(e).toExist();
+      expect(e.message).toMatch(/unknown tag/);
+    });
+
+    it('returns an empty object when the file is empty', async function () {
+      github.repos.getContent.andReturn(readConfig('empty.yml'));
+
+      const contents = await context.config('test-file.yml');
+
+      expect(contents).toEqual({});
+    });
+  });
 });

test/fixtures/config/basic.yml

@@ -0,0 +1,3 @@
+foo: 5
+bar: 7
+baz: 11

test/fixtures/config/evil.yml

@@ -0,0 +1 @@
+evil: !<tag:yaml.org,2002:js/function> 'function () {}'

test/fixtures/config/malformed.yml

@@ -0,0 +1 @@
+@