feat(helpers): add compose feature (#1660)

Author: paulbakker

lib/helpers/chainComposer.js

@@ -0,0 +1,34 @@
+'use strict';
+/* eslint-disable func-names */
+
+var Chain = require('../chain');
+var _ = require('lodash');
+
+module.exports = composeHandlerChain;
+
+/**
+ * Builds a function with the signature of a handler
+ * function(req,resp,callback).
+ * which internally executes the passed in array of handler function as a chain.
+ *
+ * @param {Array} [handlers] - handlers Array of
+ * function(req,resp,callback) handlers.
+ * @param {Object} [options] - options Optional option object that is
+ * passed to Chain.
+ * @returns {Function} Handler function that executes the handler chain when run
+ */
+function composeHandlerChain(handlers, options) {
+    var chain = new Chain(options);
+    if (_.isArray(handlers)) {
+        handlers = _.flattenDeep(handlers);
+        handlers.forEach(function(handler) {
+            chain.add(handler);
+        });
+    } else {
+        chain.add(handlers);
+    }
+
+    return function handlerChain(req, resp, callback) {
+        chain.run(req, resp, callback);
+    };
+}

lib/index.js

@@ -108,3 +108,4 @@ module.exports.createServer = createServer;
 module.exports.formatters = require('./formatters');
 module.exports.plugins = require('./plugins');
 module.exports.pre = require('./plugins').pre;
+module.exports.helpers = { compose: require('./helpers/chainComposer') };

test/chainComposer.test.js

@@ -0,0 +1,66 @@
+'use strict';
+/* eslint-disable func-names */
+
+if (require.cache[__dirname + '/lib/helper.js']) {
+    delete require.cache[__dirname + '/lib/helper.js'];
+}
+var helper = require('./lib/helper.js');
+
+///--- Globals
+
+var test = helper.test;
+var composer = require('../lib/helpers/chainComposer');
+
+test('chainComposer creates a valid chain for a handler array ', function(t) {
+    var counter = 0;
+    var handlers = [];
+    handlers.push(function(req, res, next) {
+        counter++;
+        next();
+    });
+
+    handlers.push(function(req, res, next) {
+        counter++;
+        next();
+    });
+
+    var chain = composer(handlers);
+    chain(
+        {
+            startHandlerTimer: function() {},
+            endHandlerTimer: function() {},
+            closed: function() {
+                return false;
+            }
+        },
+        {},
+        function() {
+            t.equal(counter, 2);
+            t.done();
+        }
+    );
+});
+
+test('chainComposer creates a valid chain for a single handler', function(t) {
+    var counter = 0;
+    var handlers = function(req, res, next) {
+        counter++;
+        next();
+    };
+
+    var chain = composer(handlers);
+    chain(
+        {
+            startHandlerTimer: function() {},
+            endHandlerTimer: function() {},
+            closed: function() {
+                return false;
+            }
+        },
+        {},
+        function() {
+            t.equal(counter, 1);
+            t.done();
+        }
+    );
+});