#2325 : Add $inc support for Helpers update

src/addons/__tests__/update-test.js

@@ -79,6 +79,19 @@ describe('update', function() {
     );
   });
 
+  it('should support inc', function() {
+    expect(update(3, {$inc: 2})).toEqual(5);
+
+    expect(update.bind(null, '3', {$inc: 3})).toThrow(
+      'Invariant Violation: update(): Expected $inc target to be a number; got a string. '
+    );
+
+    expect(update.bind(null, 3, {$inc: '5'})).toThrow(
+      'Invariant Violation: update(): Expected spec of $inc to be a number; got a string. '
+    )
+
+  });
+
   it('should support deep updates', function() {
     expect(update({a: 'b', c: {d: 'e'}}, {c: {d: {$set: 'f'}}})).toEqual({
       a: 'b',
@@ -90,7 +103,7 @@ describe('update', function() {
     expect(update.bind(null, {a: 'b'}, {a: 'c'})).toThrow(
       'Invariant Violation: update(): You provided a key path to update() ' +
       'that did not contain one of $push, $unshift, $splice, $set, $merge, ' +
-      '$apply. Did you forget to include {$set: ...}?'
+      '$apply, $inc. Did you forget to include {$set: ...}?'
     );
   });
 });

src/addons/update.js

@@ -30,14 +30,16 @@ var COMMAND_SPLICE = keyOf({$splice: null});
 var COMMAND_SET = keyOf({$set: null});
 var COMMAND_MERGE = keyOf({$merge: null});
 var COMMAND_APPLY = keyOf({$apply: null});
+var COMMAND_INC = keyOf({$inc: null});
 
 var ALL_COMMANDS_LIST = [
   COMMAND_PUSH,
   COMMAND_UNSHIFT,
   COMMAND_SPLICE,
   COMMAND_SET,
   COMMAND_MERGE,
-  COMMAND_APPLY
+  COMMAND_APPLY,
+  COMMAND_INC
 ];
 
 var ALL_COMMANDS_SET = {};
@@ -151,6 +153,25 @@ function update(value, spec) {
     nextValue = spec[COMMAND_APPLY](nextValue);
   }
 
+  if (spec.hasOwnProperty(COMMAND_INC)) {
+
+    invariant(
+      typeof value === "number",
+      'update(): Expected %s target to be a number; got a %s. ',
+      COMMAND_INC,
+      typeof value
+    );
+
+    invariant(
+      typeof spec[COMMAND_INC] === "number",
+      'update(): Expected spec of %s to be a number; got a %s. ',
+      COMMAND_INC,
+      typeof spec[COMMAND_INC]
+    );
+
+    nextValue += spec[COMMAND_INC];
+  }
+
   for (var k in spec) {
     if (!(ALL_COMMANDS_SET.hasOwnProperty(k) && ALL_COMMANDS_SET[k])) {
       nextValue[k] = update(value[k], spec[k]);