feat(sync): Add JS unittests for updateObjectValue, and refactor.

The new implementation uses `reduce`, in the hopes of producing a more
readable version than old-style loops and reassignment of object values.

umap/static/umap/js/modules/sync/updaters.js

@@ -11,20 +11,23 @@ class BaseUpdater {
   }
 
   updateObjectValue(obj, key, value) {
-    // XXX refactor so it's cleaner
-    let path = key.split('.')
-    let what
-    for (var i = 0, l = path.length; i < l; i++) {
-      what = path[i]
-      if (what === path[l - 1]) {
+    const parts = key.split('.')
+    const lastKey = parts.pop()
+
+    // Reduce the current list of attributes,
+    // to find the object to set the property onto
+    const objectToSet = parts.reduce((currentObj, part) => {
+      if (part in currentObj) return currentObj[part]
+    }, obj)
+
+    // In case the given path doesn't exist, bail out
+    if (objectToSet === undefined) return
+
+    // Set the value (or delete it)
     if (typeof value === 'undefined') {
-          delete obj[what]
+      delete objectToSet[lastKey]
     } else {
-          obj[what] = value
-        }
-      } else {
-        obj = obj[what]
-      }
+      objectToSet[lastKey] = value
     }
   }
 
@@ -54,7 +57,7 @@ export class MapUpdater extends BaseUpdater {
 }
 
 export class DataLayerUpdater extends BaseUpdater {
-  upsert({ key, metadata, value }) {
+  upsert({ value }) {
     // Inserts does not happen (we use multiple updates instead).
     this.map.createDataLayer(value, false)
   }

umap/static/umap/unittests/updaters.js

@@ -0,0 +1,68 @@
+import { describe, it } from 'mocha'
+
+import pkg from 'chai'
+const { expect } = pkg
+
+import {
+  MapUpdater,
+  DataLayerUpdater,
+  FeatureUpdater,
+} from '../js/modules/sync/updaters.js'
+
+describe('Updaters', () => {
+  describe('BaseUpdater', function () {
+    let updater
+    let map
+    let obj
+
+    this.beforeEach(function () {
+      map = {}
+      updater = new MapUpdater(map)
+      obj = {}
+    })
+    it('should be able to set object properties', function () {
+      let obj = {}
+      updater.updateObjectValue(obj, 'foo', 'foo')
+      expect(obj).deep.equal({ foo: 'foo' })
+    })
+
+    it('should be able to set object properties recursively on existing objects', function () {
+      let obj = { foo: {} }
+      updater.updateObjectValue(obj, 'foo.bar', 'foo')
+      expect(obj).deep.equal({ foo: { bar: 'foo' } })
+    })
+
+    it('should be able to set object properties recursively on deep objects', function () {
+      let obj = { foo: { bar: { baz: {} } } }
+      updater.updateObjectValue(obj, 'foo.bar.baz.test', 'value')
+      expect(obj).deep.equal({ foo: { bar: { baz: { test: 'value' } } } })
+    })
+
+    it('should be able to replace object properties recursively on deep objects', function () {
+      let obj = { foo: { bar: { baz: { test: 'test' } } } }
+      updater.updateObjectValue(obj, 'foo.bar.baz.test', 'value')
+      expect(obj).deep.equal({ foo: { bar: { baz: { test: 'value' } } } })
+    })
+
+    it('should not set object properties recursively on non-existing objects', function () {
+      let obj = { foo: {} }
+      updater.updateObjectValue(obj, 'bar.bar', 'value')
+
+      expect(obj).deep.equal({ foo: {} })
+    })
+
+    it('should delete keys for undefined values', function () {
+      let obj = { foo: 'foo' }
+      updater.updateObjectValue(obj, 'foo', undefined)
+
+      expect(obj).deep.equal({})
+    })
+
+    it('should delete keys for undefined values, recursively', function () {
+      let obj = { foo: { bar: 'bar' } }
+      updater.updateObjectValue(obj, 'foo.bar', undefined)
+
+      expect(obj).deep.equal({ foo: {} })
+    })
+  })
+})