feat(voting): add function for managing next voting entries

Author: androide-osorio

src/core.js

@@ -1,7 +1,7 @@
 /*
  * Core application logic
  */
-import { List } from 'immutable';
+import { List, Map } from 'immutable';
 
 /**
  * set the entries of the app's state
@@ -12,3 +12,18 @@ import { List } from 'immutable';
 export function setEntries(state, entries = []) {
   return state.set('entries', new List(entries));
 }
+
+/**
+ * extracts the next two entries for vote
+ * e.g: the first two entries in the list.
+ * @param  {Immutable.Map}   state the application's current state
+ * @return {Immutable.Map}         modified state
+ */
+export function next(state) {
+  const entries = state.get('entries');
+
+  return state.merge({
+    vote: new Map({ pair: entries.take(2) }),
+    entries: entries.skip(2)
+  });
+}

test/core_spec.js

@@ -1,13 +1,13 @@
 import { expect } from 'chai';
 import { List, Map } from 'immutable';
 
-import { setEntries } from '../src/core';
+import { setEntries, next } from '../src/core';
 
 // describe application logic
 describe('Application Logic', () => {
-  describe('setEntries', () => {
-    let state = null;
+  let state = null;
 
+  describe('setEntries', () => {
     beforeEach(() => {
       // runs before each test in this block
       state = new Map();
@@ -32,4 +32,24 @@ describe('Application Logic', () => {
       expect(nextState.get('entries')).to.equal(List.of(...entries));
     });
   });
+
+  describe('next', () => {
+    beforeEach(() => {
+      state = new Map({
+        entries: List.of('Kill Bill', 'Pulp Fiction', 'Reservoir Dogs')
+      });
+    });
+
+    // the next vote reducer should take the next two entries
+    // in the state and put them under vote. it should also remove
+    // those voting entries from the 'entries' map in the state.
+    it('takes the next two entries under vote', () => {
+      const nextState = next(state);
+
+      expect(nextState).to.include.key('vote');
+      expect(nextState.get('vote')).to.include.key('pair');
+      expect(nextState.get('vote').get('pair')).to.have.sizeOf(2);
+      expect(nextState.get('vote').get('pair')).to.equal(List.of('Kill Bill', 'Pulp Fiction'));
+    });
+  });
 });