Adding summarization code in its own module

summarization.js

@@ -0,0 +1,44 @@
+"use strict";
+
+const addTxn = function(acc, txn){
+  switch(txn.type){
+  case "deposit":
+	  acc.deposit += txn.amount
+    break
+
+  case "laundry":
+	  acc.laundry += txn.amount
+	  break
+
+  case "purchase":
+    acc.purchase += txn.amount
+    break
+  }
+  return acc
+}
+
+const calculateTotal = function(monies) {
+  return monies.deposit - (monies.laundry + monies.purchase);
+}
+
+const summarizeStudent = function(student){
+  let monies = student.txns.reduce(addTxn, {deposit: 0,laundry: 0,purchase: 0, total:0});
+  monies.total = calculateTotal(monies);
+  return {
+    name : student.name,
+    roomNo : student.roomNo,
+    seatNo : student.seatNo,
+    monies : monies
+  }
+
+}
+
+const summarize = function(students) {
+  return students.map(summarizeStudent);
+}
+
+module.exports = {
+  addTxn,
+  summarizeStudent,
+  summarize
+}

test/summarization_test.js

@@ -0,0 +1,57 @@
+var assert = require('assert');
+var summarization = require('../summarization.js');
+var models = require('../models.js');
+
+describe('summarization', function() {
+  describe('addTxn', function() {
+
+    it('sums deposits', function() {
+      // TODO: replace manual object construction with factories or builders
+      var deposit20 = {type: "deposit", amount: 20};
+      var deposit10 = {type: "deposit", amount: 10};
+      var acc1 = summarization.addTxn({deposit: 0, laundry: 0, purchase: 0}, deposit20);
+      var acc2 = summarization.addTxn(acc1, deposit10);
+      assert.equal(30, acc2.deposit);
+    });
+
+    it('sums laundry', function() {
+      var laundry20 = {type: "laundry", amount: 20};
+      var laundry10 = {type: "laundry", amount: 10};
+      var acc1 = summarization.addTxn({deposit: 0, laundry: 0, purchase: 0}, laundry20);
+      var acc2 = summarization.addTxn(acc1, laundry10);
+      assert.equal(30, acc2.laundry);
+    });
+
+    it('sums purchase', function() {
+      var purchase20 = {type: "purchase", amount: 20};
+      var purchase10 = {type: "purchase", amount: 10};
+      var acc1 = summarization.addTxn({deposit: 0, laundry: 0, purchase: 0}, purchase20);
+      var acc2 = summarization.addTxn(acc1, purchase10);
+      assert.equal(30, acc2.purchase);
+    });
+
+    it('summarizes multiple students', function() {
+      var john = {name: "john", roomNo: "1a", seatNo:"2a",
+                  txns: [{type: "deposit", amount: 200},
+                         {type: "laundry", amount: 10},
+                         {type: "laundry", amount: 30},
+                         {type: "laundry", amount: 20},
+                         {type: "purchase", amount: 50},
+                         {type: "purchase", amount: 100}]};
+      var mukesh = {name: "mukesh", roomNo: "2a", seatNo: "3a",
+                    txns: [{type: "deposit", amount: 200},
+                           {type: "laundry", amount: 10},
+                           {type: "laundry", amount: 50},
+                           {type: "laundry", amount: 20},
+                           {type: "purchase", amount: 50}]};
+      var summary = [
+        {name:"john", roomNo: "1a", seatNo: "2a",
+         monies: {deposit: 200, laundry: 60, purchase: 150, total: -10}},
+        {name:"mukesh", roomNo: "2a", seatNo: "3a",
+         monies: {deposit: 200, laundry: 80, purchase: 50, total: 70}}
+      ];
+      assert.deepEqual(summary, summarization.summarize([john, mukesh]));
+    });
+
+  });
+});