feat(lib): implement object diff detector (#55)

src/lib/object-diff.js

@@ -0,0 +1,27 @@
+var assert = require('assert')
+
+function difference(a, b) {
+  var diff = {}
+
+  Object.keys(a).forEach(compare(diff, a, b))
+  Object.keys(b).forEach(compare(diff, a, b))
+
+  return diff
+}
+
+function compare(diff, a, b) {
+  return function curried(n) {
+    if (!diff[n]) {
+      try {
+        assert.deepEqual(a[n], b[n])
+      } catch (e) {
+        diff[n] = {
+          config1: a[n],
+          config2: b[n],
+        }
+      }
+    }
+  }
+}
+
+module.exports = difference

test/lib/object-diff.js

@@ -0,0 +1,27 @@
+var assert = require('assert')
+var difference = require('../../src/lib/object-diff')
+
+describe('object difference', function() {
+  it('should return difference', function() {
+    assert.deepEqual(
+      difference({'foo-rule': [2, 'foo']}, {'foo-rule': [2, 'bar']}),
+      {'foo-rule': {config1: [2, 'foo'], config2: [2, 'bar']}}
+    )
+    assert.deepEqual(
+      difference({'foo-rule': [2, 'foo', 'bar']}, {'foo-rule': 2}),
+      {'foo-rule': {config1: [2, 'foo', 'bar'], config2: 2}}
+    )
+    assert.deepEqual(
+      difference({'foo-rule': [0, 'foo']}, {'bar-rule': [1, 'bar']}),
+      {
+        'foo-rule': {config1: [0, 'foo'], config2: undefined},
+        'bar-rule': {config1: undefined, config2: [1, 'bar']},
+      }
+    )
+
+    assert.deepEqual(
+      difference({'foo-rule': [1, 'foo', 'bar']}, {'foo-rule': [1, 'foo', 'bar']}),
+      {}
+    )
+  })
+})