[New] oneOfType: Add expected types to warning

Adds data object to returned error in checker so that the expected types can be accessed from within oneOfType check. Also, updates the tests slightly.

Fixes #9.

__tests__/PropTypesDevelopmentReact15.js

@@ -1080,7 +1080,7 @@ describe('PropTypesDevelopmentReact15', () => {
       typeCheckFail(
         PropTypes.oneOfType([PropTypes.string, PropTypes.number]),
         [],
-        'Invalid prop `testProp` supplied to `testComponent`.',
+        'Invalid prop `testProp` supplied to `testComponent`, expected one of type [string, number].',
       );
 
       const checker = PropTypes.oneOfType([

__tests__/PropTypesDevelopmentStandalone-test.js

@@ -1154,7 +1154,7 @@ describe('PropTypesDevelopmentStandalone', () => {
       typeCheckFail(
         PropTypes.oneOfType([PropTypes.string, PropTypes.number]),
         [],
-        'Invalid prop `testProp` supplied to `testComponent`.',
+        'Invalid prop `testProp` supplied to `testComponent`, expected one of type [string, number].',
       );
 
       const checker = PropTypes.oneOfType([

factoryWithTypeCheckers.js

@@ -159,8 +159,9 @@ module.exports = function(isValidElement, throwOnDirectAccess) {
    * is prohibitively expensive if they are created too often, such as what
    * happens in oneOfType() for any type before the one that matched.
    */
-  function PropTypeError(message) {
+  function PropTypeError(message, data) {
     this.message = message;
+    this.data = data && typeof data === 'object' ? data: {};
     this.stack = '';
   }
   // Make `instanceof Error` still work for returned errors.
@@ -234,7 +235,10 @@ module.exports = function(isValidElement, throwOnDirectAccess) {
         // 'of type `object`'.
         var preciseType = getPreciseType(propValue);
 
-        return new PropTypeError('Invalid ' + location + ' `' + propFullName + '` of type ' + ('`' + preciseType + '` supplied to `' + componentName + '`, expected ') + ('`' + expectedType + '`.'));
+        return new PropTypeError(
+          'Invalid ' + location + ' `' + propFullName + '` of type ' + ('`' + preciseType + '` supplied to `' + componentName + '`, expected ') + ('`' + expectedType + '`.'),
+          {expectedType: expectedType}
+        );
       }
       return null;
     }
@@ -378,14 +382,19 @@ module.exports = function(isValidElement, throwOnDirectAccess) {
     }
 
     function validate(props, propName, componentName, location, propFullName) {
+      var expectedTypes = [];
       for (var i = 0; i < arrayOfTypeCheckers.length; i++) {
         var checker = arrayOfTypeCheckers[i];
-        if (checker(props, propName, componentName, location, propFullName, ReactPropTypesSecret) == null) {
+        var checkerResult = checker(props, propName, componentName, location, propFullName, ReactPropTypesSecret);
+        if (checkerResult == null) {
           return null;
         }
+        if (checkerResult.data.hasOwnProperty('expectedType')) {
+          expectedTypes.push(checkerResult.data.expectedType);
+        }
       }
-
-      return new PropTypeError('Invalid ' + location + ' `' + propFullName + '` supplied to ' + ('`' + componentName + '`.'));
+      var expectedTypesMessage = (expectedTypes.length > 0) ? ', expected one of type [' + expectedTypes.join(', ') + ']': '';
+      return new PropTypeError('Invalid ' + location + ' `' + propFullName + '` supplied to ' + ('`' + componentName + '`' + expectedTypesMessage + '.'));
     }
     return createChainableTypeChecker(validate);
   }