Add _.update.

test/test-fp.js

@@ -563,7 +563,7 @@
         deepObject = { 'a': { 'b': 2, 'c': 3 } };
 
     QUnit.test('should not mutate values', function(assert) {
-      assert.expect(38);
+      assert.expect(40);
 
       function Foo() {}
       Foo.prototype = { 'b': 2 };
@@ -695,6 +695,12 @@
 
       assert.deepEqual(value, deepObject, 'fp.unset');
       assert.deepEqual(actual, { 'a': { 'c': 3 } }, 'fp.unset');
+
+      value = _.cloneDeep(deepObject);
+      actual = fp.update(function(x) { return x + 1; })('a.b')(value);
+
+      assert.deepEqual(value, deepObject, 'fp.update');
+      assert.deepEqual(actual, { 'a': { 'b': 3, 'c': 3 } }, 'fp.update');
     });
   }());
 
@@ -742,7 +748,7 @@
         deepObject = { 'a': { 'b': 2, 'c': 3 } };
 
     QUnit.test('should only clone objects in `path`', function(assert) {
-      assert.expect(8);
+      assert.expect(9);
 
       var object = { 'a': { 'b': { 'c': 1 }, 'd': { 'e': 1 } } },
           value = _.cloneDeep(object),
@@ -765,6 +771,10 @@
 
       assert.notOk('b' in actual, 'fp.unset');
       assert.strictEqual(actual.d, value.d, 'fp.unset');
+
+      value = _.cloneDeep(object);
+      actual = fp.update(function(x) { return { 'c2': 2 }; }, 'a.b', value);
+      assert.strictEqual(actual.d, value.d, 'fp.update');
     });
   }());
 

test/test.js

@@ -18439,6 +18439,25 @@
 
   /*--------------------------------------------------------------------------*/
 
+  QUnit.module('lodash.update');
+
+  (function() {
+    QUnit.test('should call `func` with existing value on `path` of `object` and update it', function(assert) {
+      assert.expect(2);
+
+      var object = { 'a': [{ 'b': { 'c': 10 } }] };
+
+      _.update(object, ['a', 0, 'b', 'c'], function(value) {
+        assert.equal(value, 10);
+        return 20;
+      });
+
+      assert.equal(object.a[0].b.c, 20);
+    });
+  }());
+
+  /*--------------------------------------------------------------------------*/
+
   QUnit.module('set methods');
 
   lodashStable.each(['set', 'setWith'], function(methodName) {
@@ -24389,7 +24408,7 @@
     var acceptFalsey = lodashStable.difference(allMethods, rejectFalsey);
 
     QUnit.test('should accept falsey arguments', function(assert) {
-      assert.expect(298);
+      assert.expect(299);
 
       var emptyArrays = lodashStable.map(falsey, alwaysEmptyArray);