Add exact type checker from react native (#41)

__tests__/PropTypesDevelopmentReact15.js

@@ -1045,6 +1045,113 @@ describe('PropTypesDevelopmentReact15', () => {
     });
   });
 
+  describe('Exact Types', () => {
+    it('should warn for non objects', () => {
+      typeCheckFail(
+        PropTypes.exact({}),
+        'some string',
+        'Invalid prop `testProp` of type `string` supplied to ' +
+          '`testComponent`, expected `object`.',
+      );
+      typeCheckFail(
+        PropTypes.exact({}),
+        ['array'],
+        'Invalid prop `testProp` of type `array` supplied to ' +
+          '`testComponent`, expected `object`.',
+      );
+    });
+
+    it('should not warn for empty values', () => {
+      typeCheckPass(PropTypes.exact({}), undefined);
+      typeCheckPass(PropTypes.exact({}), null);
+      typeCheckPass(PropTypes.exact({}), {});
+    });
+
+    it('should not warn for an empty object', () => {
+      typeCheckPass(PropTypes.exact({}).isRequired, {});
+    });
+
+    it('should warn for non specified types', () => {
+      typeCheckFail(
+        PropTypes.exact({}),
+        {key: 1},
+        'Warning: Failed prop type: Invalid prop `testProp` key `key` supplied to `testComponent`.' +
+        '\nBad object: {' +
+        '\n  \"key\": 1' +
+        '\n}' +
+        '\nValid keys: []'
+      );
+    });
+
+    it('should not warn for valid types', () => {
+      typeCheckPass(PropTypes.exact({key: PropTypes.number}), {key: 1});
+    });
+
+    it('should warn for required valid types', () => {
+      typeCheckFail(
+        PropTypes.exact({key: PropTypes.number.isRequired}),
+        {},
+        'The prop `testProp.key` is marked as required in `testComponent`, ' +
+          'but its value is `undefined`.',
+      );
+    });
+
+    it('should warn for the first required type', () => {
+      typeCheckFail(
+        PropTypes.exact({
+          key: PropTypes.number.isRequired,
+          secondKey: PropTypes.number.isRequired,
+        }),
+        {},
+        'The prop `testProp.key` is marked as required in `testComponent`, ' +
+          'but its value is `undefined`.',
+      );
+    });
+
+    it('should warn for invalid key types', () => {
+      typeCheckFail(
+        PropTypes.exact({key: PropTypes.number}),
+        {key: 'abc'},
+        'Invalid prop `testProp.key` of type `string` supplied to `testComponent`, ' +
+          'expected `number`.',
+      );
+    });
+
+    it('should be implicitly optional and not warn without values', () => {
+      typeCheckPass(
+        PropTypes.exact(PropTypes.exact({key: PropTypes.number})),
+        null,
+      );
+      typeCheckPass(
+        PropTypes.exact(PropTypes.exact({key: PropTypes.number})),
+        undefined,
+      );
+    });
+
+    it('should warn for missing required values', () => {
+      typeCheckFailRequiredValues(
+        PropTypes.exact({key: PropTypes.number}).isRequired,
+      );
+    });
+
+    it('should warn if called manually in development', () => {
+      spyOn(console, 'error');
+      expectWarningInDevelopment(PropTypes.exact({}), 'some string');
+      expectWarningInDevelopment(PropTypes.exact({foo: PropTypes.number}), {
+        foo: 42,
+      });
+      expectWarningInDevelopment(
+        PropTypes.exact({key: PropTypes.number}).isRequired,
+        null,
+      );
+      expectWarningInDevelopment(
+        PropTypes.exact({key: PropTypes.number}).isRequired,
+        undefined,
+      );
+      expectWarningInDevelopment(PropTypes.element, <div />);
+    });
+  });
+
   describe('Symbol Type', () => {
     it('should warn for non-symbol', () => {
       typeCheckFail(

factoryWithTypeCheckers.js

@@ -110,7 +110,8 @@ module.exports = function(isValidElement, throwOnDirectAccess) {
     objectOf: createObjectOfTypeChecker,
     oneOf: createEnumTypeChecker,
     oneOfType: createUnionTypeChecker,
-    shape: createShapeTypeChecker
+    shape: createShapeTypeChecker,
+    exact: createStrictShapeTypeChecker,
   };
 
   /**
@@ -379,6 +380,36 @@ module.exports = function(isValidElement, throwOnDirectAccess) {
     return createChainableTypeChecker(validate);
   }
 
+  function createStrictShapeTypeChecker(shapeTypes) {
+    function validate(props, propName, componentName, location, propFullName) {
+      var propValue = props[propName];
+      var propType = getPropType(propValue);
+      if (propType !== 'object') {
+        return new PropTypeError('Invalid ' + location + ' `' + propFullName + '` of type `' + propType + '` ' + ('supplied to `' + componentName + '`, expected `object`.'));
+      }
+      // We need to check all keys in case some are required but missing from
+      // props.
+      var allKeys = Object.assign({}, props[propName], shapeTypes);
+      for (var key in allKeys) {
+        var checker = shapeTypes[key];
+        if (!checker) {
+          return new PropTypeError(
+            'Invalid ' + location + ' `' + propFullName + '` key `' + key + '` supplied to `' + componentName + '`.' +
+            '\nBad object: ' + JSON.stringify(props[propName], null, '  ') +
+            '\nValid keys: ' +  JSON.stringify(Object.keys(shapeTypes), null, '  ')
+          );
+        }
+        var error = checker(propValue, key, componentName, location, propFullName + '.' + key, ReactPropTypesSecret);
+        if (error) {
+          return error;
+        }
+      }
+      return null;
+    }
+
+    return createChainableTypeChecker(validate);
+  }
+
   function isNode(propValue) {
     switch (typeof propValue) {
       case 'number':