Finish group-by util

Move function to util, add tests.

app/services/kredits.js

@@ -2,12 +2,12 @@ import ethers from 'npm:ethers';
 import Kredits from 'npm:kredits-contracts';
 import RSVP from 'rsvp';
 
-import { A } from '@ember/array';
 import Service from '@ember/service';
-import { computed, get } from '@ember/object';
+import { computed } from '@ember/object';
 import { alias, notEmpty } from '@ember/object/computed';
-import { isEmpty, isPresent } from '@ember/utils';
+import { isEmpty } from '@ember/utils';
 
+import groupBy from 'kredits-web/utils/group-by';
 import formatKredits from 'kredits-web/utils/format-kredits';
 
 import config from 'kredits-web/config/environment';
@@ -15,27 +15,6 @@ import Contributor from 'kredits-web/models/contributor'
 import Proposal from 'kredits-web/models/proposal'
 import Contribution from 'kredits-web/models/contribution'
 
-function groupBy (collection, property) {
-  let groups = A();
-  let items = collection;
-
-  if (items) {
-    items.forEach(function(item) {
-      let value = get(item, property);
-      let group = groups.findBy('value', value);
-
-      if (isPresent(group)) {
-        get(group, 'items').push(item);
-      } else {
-        group = { property: property, value: value, items: [item] };
-        groups.push(group);
-      }
-    });
-  }
-
-  return groups;
-}
-
 export default Service.extend({
 
   currentBlock: null,

app/utils/group-by.js

@@ -0,0 +1,27 @@
+//
+// Code from https://github.com/HeroicEric/ember-group-by (MIT licensed)
+//
+import { A } from '@ember/array';
+import { get } from '@ember/object';
+import { isPresent } from '@ember/utils';
+
+export default function groupBy (collection, property) {
+  let groups = A();
+  let items = collection;
+
+  if (items) {
+    items.forEach(function(item) {
+      let value = get(item, property);
+      let group = groups.findBy('value', value);
+
+      if (isPresent(group)) {
+        get(group, 'items').push(item);
+      } else {
+        group = { property: property, value: value, items: [item] };
+        groups.push(group);
+      }
+    });
+  }
+
+  return groups;
+}

tests/unit/utils/group-by-test.js

@@ -0,0 +1,41 @@
+//
+// Code adapted from https://github.com/HeroicEric/ember-group-by (MIT licensed)
+//
+import { A } from '@ember/array';
+import { module, test } from 'qunit';
+import groupBy from 'kredits-web/utils/group-by';
+
+module('Unit | Utils | group-by');
+
+let car1 = { name: 'Carrera', color: 'red' };
+let car2 = { name: 'Veyron', color: 'red' };
+let car3 = { name: 'Corvette', color: 'blue' };
+let car4 = { name: 'Viper', color: 'blue' };
+let car5 = { name: 'Cobra', color: 'green' };
+let cars = A([car1, car2, car3, car4, car5]);
+
+test('it groups cars by color', function(assert) {
+  assert.expect(1);
+  let redGroup = { property: 'color', value: 'red', items: [car1, car2] };
+  let blueGroup = { property: 'color', value: 'blue', items: [car3, car4] };
+  let greenGroup = { property: 'color', value: 'green', items: [car5] };
+
+  let result = groupBy(cars, 'color');
+  let expected = [redGroup, blueGroup, greenGroup];
+
+  assert.deepEqual(result, expected);
+});
+
+test('it does not fail with empty array', function(assert) {
+  let cars = [];
+
+  let result = groupBy(cars, 'color');
+  assert.deepEqual(result, []);
+});
+
+test('it does not failkwith null', function(assert) {
+  let cars = null;
+
+  let result = groupBy(cars, 'color');
+  assert.deepEqual(result, []);
+});