feat(objectDiff): add object diff util

src/utils/utils.js

@@ -1,3 +1,15 @@
+import _ from 'lodash'
+
 /**
- * Created by levithomason on 5/6/16.
+ * This method is naive and inefficient, intended for development / debugging use only.
+ * Deleted keys are shown as [DELETED].
+ * @param {{}} source The source object
+ * @param {{}} target The target object.
+ * @returns {{}} A new object containing new/modified/deleted keys.
  */
+export const objectDiff = (source, target) => _.transform(source, (res, val, key) => {
+  // deleted keys
+  if (!_.has(target, key)) res[key] = '[DELETED]'
+  // new keys / changed values
+  else if (!_.isEqual(val, target[key])) res[key] = target[key]
+}, {})

test/specs/utils/utils-test.js

@@ -0,0 +1,60 @@
+import _ from 'lodash'
+
+import * as utils from '../../../src/utils/utils'
+
+describe('objectDiff', () => {
+  let a
+  let b
+  beforeEach(() => {
+    [a, b] = _.times(2, n => ({
+      undef: undefined,
+      nil: null,
+      bool: true,
+      num: 1,
+      str: 'foo',
+      obj: { key: 'val', nested: { key: 'val' } },
+      func: _.noop,
+    }))
+  })
+
+  const assertDiff = (diff) => utils.objectDiff(a, b).should.deep.equal(diff)
+
+  it('picks up undefined values', () => {
+    b.nil = undefined
+    assertDiff({ nil: undefined })
+  })
+  it('picks up null values', () => {
+    b.undef = null
+    assertDiff({ undef: null })
+  })
+  it('picks up boolean values', () => {
+    b.undef = true
+    assertDiff({ undef: true })
+
+    b.undef = false
+    assertDiff({ undef: false })
+  })
+  it('picks up number values', () => {
+    b.undef = 0
+    assertDiff({ undef: 0 })
+
+    b.undef = 1
+    assertDiff({ undef: 1 })
+  })
+  it('picks up string values', () => {
+    b.undef = 'string'
+    assertDiff({ undef: 'string' })
+  })
+  it('picks up object values', () => {
+    b.obj.key = 'new value'
+    assertDiff({ obj: b.obj })
+  })
+  it('picks up nested object values', () => {
+    b.obj.nested.key = 'new nested value'
+    assertDiff({ obj: b.obj })
+  })
+  it('shows deleted keys', () => {
+    delete b.undef
+    assertDiff({ undef: '[DELETED]' })
+  })
+})