testing API's with buster

example.js

'use strict';

var buster = require('buster');
var testApi = require('./test-http');

function exampleApp () {
  return function (req, res) {
    res.setHeader('content-type', 'text/plain');
    res.setHeader('content-length', req.url.length);
    res.end(req.url);
  };
}

buster.testCase('Echo server', testApi(exampleApp, {
  // You can use `this.request(path, options)` in setUp
  setUp: function () {
    this.expectedContentType = 'text/plain';
  },
  
  // Using tearDown to assert common post-conditions
  tearDown: function () {
    if (this.response) {
      buster.assert.equals(this.response.headers['content-type'],
                           this.expectedContentType,
                           'Maybe you need to set this.expectedContentType in your test?');
    }
  },

  'GET /a/static/path': function (response) {
    // Use an argument, or not.
    buster.assert.same(this.response, response);
    buster.assert.equals('/a/static/path', response.body);
  },
  
  'GET /a/:parameterized/path': {
    // use getParams on individual requests. This can also return a promise.
    getParams: function () {
      return { parameterized: 'something' };
    },
    assertions: function (response) {
      buster.assert.equals(response.body, '/a/something/path');
    }
  }
}));

test-http.js

'use strict';

var http = require('http');
var url = require('url');

var Promise = require('bluebird');
var questor = require('questor');
var buster = require('buster');

module.exports = function testHttpApp (createApp, tests) {

  Object.keys(tests).forEach(function (key) {
    var match = key.match(/^(GET|PUT|POST|DELETE|HEAD) (\/[^ ]*)$/);
    if (match) {
      var test = createRequestTest(createApp, match[1], match[2], tests[key]);
      tests[test.testName || key] = test;
    }
  });

  tests.setUp = before(tests.setUp, function (next) {
    var self = this;
    this.app = createApp();
    this.server = http.createServer(this.app)
      .listen(0, 'localhost')
      .on('listening', function () {
        var port = self.server.address().port;
        self.request = function (path, options) {
          var uri = url.format({
            hostname: 'localhost',
            port: port,
            protocol: 'http:',
            pathname: path
          });
          return questor(uri, options);
        };
        next();
      });
  });

  tests.tearDown = before(tests.tearDown, function (next) {
    this.server.close();
    this.server.on('close', next);
  });

  return tests;
};

function createRequestTest (createApp, method, path, test) {
  return function () {
    var self = this;

    if (typeof test !== 'object' || !test.assertions) {
      test = {
        assertions: test
      };
    }

    var params = test.getParams ? test.getParams.call(this) : {};

    return Promise.resolve(params).then(function (params) {
      if (params) {
        path = path.replace(/:(\w+)/g, function (_, name) {
          if (name in params) {
            return params[name];
          } else {
            throw new Error('Parameter not defined: ' + name);
          }
        });
      }
      var options = { method: method };
      if (test.headers) { options.headers = test.headers; }
      if (test.body) { options.body = test.body; }
      return self.request(path, options).then(function (response) {
        self.response = response;
        return checkResponse(self, test.assertions, response);
      });
    });
  };
}

function checkResponse (test, assertions, response) {
  if (typeof assertions === 'function') {
    return assertions.call(test, response);
  }
  if (Array.isArray(assertions)) {
    return Promise.reduce(assertions, function (_, assertion) {
      return assertion.call(test, response).return(_);
    });
  }
  if (typeof assertions === 'object') {
    buster.assert.match(response, assertions);
  }
}

function before (original, first) {
  return function (done) {
    var self = this;
    first.call(self, function () {
      if (original) {
        original.call(self, done);
        if (!original.length) {
          done();
        }
      } else {
        done();
      }
    });
  };
}