fix: React 16 issues (fixes #269, #200, #259)

* Check if both element and props are frozen or not extensible (#200)

Fixes #200

* Only check extensiblity of props

Also run preventExtensions on it after modifications

* Check if just the props are frozen (#266)

* Recursively map element arrays

Fixes #259

* Add tests

For element arrays and frozen elements/props

Author: EmmaSimon

src/linkClass.js

@@ -22,17 +22,26 @@ const linkArray = (array: Array, styles: Object, configuration: Object) => {
 
 const linkElement = (element: ReactElement, styles: Object, configuration: Object): ReactElement => {
   let appendClassName;
-  let elementIsFrozen;
   let elementShallowCopy;
 
   elementShallowCopy = element;
 
-  if (Object.isFrozen && Object.isFrozen(elementShallowCopy)) {
-    elementIsFrozen = true;
+  if (Array.isArray(elementShallowCopy)) {
+    return elementShallowCopy.map((arrayElement) => {
+      return linkElement(arrayElement, styles, configuration);
+    });
+  }
 
-        // https://github.com/facebook/react/blob/v0.13.3/src/classic/element/ReactElement.js#L131
+  const elementIsFrozen = Object.isFrozen && Object.isFrozen(elementShallowCopy);
+  const propsFrozen = Object.isFrozen && Object.isFrozen(elementShallowCopy.props);
+  const propsNotExtensible = Object.isExtensible && !Object.isExtensible(elementShallowCopy.props);
+
+  if (elementIsFrozen) {
+    // https://github.com/facebook/react/blob/v0.13.3/src/classic/element/ReactElement.js#L131
     elementShallowCopy = objectUnfreeze(elementShallowCopy);
     elementShallowCopy.props = objectUnfreeze(elementShallowCopy.props);
+  } else if (propsFrozen || propsNotExtensible) {
+    elementShallowCopy.props = objectUnfreeze(elementShallowCopy.props);
   }
 
   const styleNames = parseStyleName(elementShallowCopy.props.styleName || '', configuration.allowMultiple);
@@ -76,6 +85,12 @@ const linkElement = (element: ReactElement, styles: Object, configuration: Objec
   if (elementIsFrozen) {
     Object.freeze(elementShallowCopy.props);
     Object.freeze(elementShallowCopy);
+  } else if (propsFrozen) {
+    Object.freeze(elementShallowCopy.props);
+  }
+
+  if (propsNotExtensible) {
+    Object.preventExtensions(elementShallowCopy.props);
   }
 
   return elementShallowCopy;

tests/linkClass.js

@@ -1,4 +1,4 @@
-/* eslint-disable max-nested-callbacks, react/prefer-stateless-function, class-methods-use-this, no-console */
+/* eslint-disable max-nested-callbacks, react/prefer-stateless-function, class-methods-use-this, no-console, no-unused-expressions */
 
 import chai, {
     expect
@@ -239,6 +239,76 @@ describe('linkClass', () => {
     });
   });
 
+  context('can\'t write to properties', () => {
+    context('when the element is frozen', () => {
+      it('adds className but is still frozen', () => {
+        let subject;
+
+        subject = <div styleName='foo' />;
+
+        Object.freeze(subject);
+        subject = linkClass(subject, {
+          foo: 'foo-1'
+        });
+
+        expect(subject).to.be.frozen;
+        expect(subject.props.className).to.equal('foo-1');
+      });
+    });
+    context('when the element\'s props are frozen', () => {
+      it('adds className and only props are still frozen', () => {
+        let subject;
+
+        subject = <div styleName='foo' />;
+
+        Object.freeze(subject.props);
+        subject = linkClass(subject, {
+          foo: 'foo-1'
+        });
+
+        expect(subject.props).to.be.frozen;
+        expect(subject.props.className).to.equal('foo-1');
+      });
+    });
+    context('when the element\'s props are not extensible', () => {
+      it('adds className and props are still not extensible', () => {
+        let subject;
+
+        subject = <div styleName='foo' />;
+
+        Object.preventExtensions(subject.props);
+        subject = linkClass(subject, {
+          foo: 'foo-1'
+        });
+
+        expect(subject.props).to.not.be.extensible;
+        expect(subject.props.className).to.equal('foo-1');
+      });
+    });
+  });
+
+  context('when element is an array', () => {
+    it('handles each element individually', () => {
+      let subject;
+
+      subject = [
+        <div key={1} styleName='foo' />,
+        <div key={2}>
+          <p styleName='bar' />
+        </div>
+      ];
+
+      subject = linkClass(subject, {
+        bar: 'bar-1',
+        foo: 'foo-1'
+      });
+
+      expect(subject).to.be.an('array');
+      expect(subject[0].props.className).to.equal('foo-1');
+      expect(subject[1].props.children.props.className).to.equal('bar-1');
+    });
+  });
+
   describe('options.allowMultiple', () => {
     context('when multiple module names are used', () => {
       context('when false', () => {