[New] checkPropTypes: add argument that allows external logging

When specified, the argument `warningLogger` will be called with the
same arguments as `warning`. Instead of logging errors to the fbjs
warning logger, we are able to handle them externally.

Fixes facebook#34

__tests__/PropTypesDevelopmentStandalone-test.js

@@ -248,6 +248,27 @@ describe('PropTypesDevelopmentStandalone', () => {
       expectInvalidValidatorWarning(PropTypes.exact({ bar: 'true' }), 'string');
       expectInvalidValidatorWarning(PropTypes.exact({ bar: null }), 'null');
     });
+
+    it('calls the passed in warning logger', () => {
+      const warningLogger = jest.fn()
+      const propTypes = {
+        foo(props, propName, componentName) {
+          throw new Error('some error');
+        },
+      };
+      const props = {foo: 'foo'};
+      const returnValue = PropTypes.checkPropTypes(
+        propTypes,
+        props,
+        'prop',
+        'testComponent',
+        null,
+        warningLogger,
+      );
+
+      expect(warningLogger).toBeCalledWith('Failed prop type: some error');
+      expect(returnValue).toBe(undefined);
+    });
   });
 
   describe('resetWarningCache', () => {
@@ -262,6 +283,7 @@ describe('PropTypesDevelopmentStandalone', () => {
         'testComponent',
         null,
       );
+
       PropTypes.resetWarningCache();
       PropTypes.checkPropTypes(
         propTypes,

checkPropTypes.js

@@ -80,7 +80,8 @@ function checkPropTypes(typeSpecs, values, location, componentName, getStack) {
 
           var stack = getStack ? getStack() : '';
 
-          printWarning(
+          var warningLogger = arguments.length > 5 ? arguments[5] : printWarning;
+          warningLogger(
             'Failed ' + location + ' type: ' + error.message + (stack != null ? stack : '')
           );
         }