feat(CSSTransition): add "done" class for appear

This is not a breaking change because it doesn't remove the
`*-enter-done` class name after appearing is done, instead
`*-appear-done` is added in addition to that class, which provides you
with a bit more control in case you wanted to define a specific
animation only when an element first appears in the DOM, not every time
it enters.

Closes #383.
Closes #327.

Changes came from #383, but had to rebase to resolve conflicts and make
modifications informed by the discussion in #327.

src/CSSTransition.js

@@ -98,7 +98,11 @@ class CSSTransition extends React.Component {
   }
 
   onEntered = (node, appearing) => {
-    const { doneClassName } = this.getClassNames('enter');
+    const appearClassName = this.getClassNames('appear').doneClassName;
+    const enterClassName = this.getClassNames('enter').doneClassName;
+    const doneClassName = appearing
+      ? `${appearClassName} ${enterClassName}`
+      : enterClassName;
 
     this.removeClasses(node, appearing ? 'appear' : 'enter');
     addClass(node, doneClassName);
@@ -203,17 +207,29 @@ CSSTransition.propTypes = {
   ...Transition.propTypes,
 
   /**
-   * The animation classNames applied to the component as it enters, exits or has finished the transition.
-   * A single name can be provided and it will be suffixed for each stage: e.g.
+   * The animation classNames applied to the component as it enters, exits or
+   * has finished the transition. A single name can be provided and it will be
+   * suffixed for each stage: e.g.
+   *
+   * `classNames="fade"` applies `fade-enter`, `fade-enter-active`,
+   * `fade-enter-done`, `fade-exit`, `fade-exit-active`, `fade-exit-done`,
+   * `fade-appear`, `fade-appear-active`, and `fade-appear-done`.
+   *
+   * **Note**: `fade-appear-done` and `fade-enter-done` will _both_ be applied.
+   * This allows you to define different behavior for when appearing is done and
+   * when regular entering is done, using selectors like
+   * `.fade-enter-done:not(.fade-appear-done)`. For example, you could apply an
+   * epic entrance animation when element first appears in the DOM using
+   * [Animate.css](https://daneden.github.io/animate.css/). Otherwise you can
+   * simply use `fade-enter-done` for defining both cases.
    *
-   * `classNames="fade"` applies `fade-enter`, `fade-enter-active`, `fade-enter-done`,
-   * `fade-exit`, `fade-exit-active`, `fade-exit-done`, `fade-appear`, and `fade-appear-active`.
    * Each individual classNames can also be specified independently like:
    *
    * ```js
    * classNames={{
    *  appear: 'my-appear',
    *  appearActive: 'my-active-appear',
+   *  appearDone: 'my-done-appear',
    *  enter: 'my-enter',
    *  enterActive: 'my-active-enter',
    *  enterDone: 'my-done-enter',
@@ -229,8 +245,8 @@ CSSTransition.propTypes = {
    * import styles from './styles.css';
    * ```
    *
-   * you might want to use camelCase in your CSS file, that way could simply spread
-   * them instead of listing them one by one:
+   * you might want to use camelCase in your CSS file, that way could simply
+   * spread them instead of listing them one by one:
    *
    * ```js
    * classNames={{ ...styles }}
@@ -239,6 +255,7 @@ CSSTransition.propTypes = {
    * @type {string | {
    *  appear?: string,
    *  appearActive?: string,
+   *  appearDone?: string,
    *  enter?: string,
    *  enterActive?: string,
    *  enterDone?: string,
@@ -273,7 +290,6 @@ CSSTransition.propTypes = {
    */
   onEntered: PropTypes.func,
 
-
   /**
    * A `<Transition>` callback fired immediately after the 'exit' class is
    * applied.

test/CSSTransition-test.js

@@ -127,7 +127,7 @@ describe('CSSTransition', () => {
 
           onEntered={(node, isAppearing) => {
             expect(isAppearing).toEqual(true);
-            expect(node.className).toEqual('appear-test-enter-done');
+            expect(node.className).toEqual('appear-test-appear-done appear-test-enter-done');
             expect(count).toEqual(2);
             done();
           }}
@@ -137,6 +137,35 @@ describe('CSSTransition', () => {
       );
     });
 
+    it('should lose the "*-appear-done" class after leaving and entering again', (done) => {
+      const wrapper = mount(
+        <CSSTransition
+          timeout={10}
+          classNames="appear-test"
+          in={true}
+          appear={true}
+          onEntered={() => {
+            wrapper.setProps({
+              in: false,
+              onEntered: () => {},
+              onExited: (node) => {
+                expect(node.className).toBe('appear-test-exit-done')
+                wrapper.setProps({
+                  in: true,
+                  onEntered: () => {
+                    expect(node.className).toBe('appear-test-enter-done')
+                    done()
+                  }
+                })
+              }
+            })
+          }}
+        >
+          <div />
+        </CSSTransition>
+      )
+    })
+
     it('should not be appearing in normal enter mode', done => {
       let count = 0;
       mount(