add proptypes to signup form

client/modules/User/components/SignupForm.js

@@ -1,10 +1,9 @@
-import React from 'react';
+import React, { PropTypes } from 'react';
 
-class SignupForm extends React.Component {
+function SignupForm(props) {
-  render() {
+  const { fields: { username, email, password, confirmPassword }, handleSubmit } = props;
-    const { fields: { username, email, password, confirmPassword }, handleSubmit } = this.props;
   return (
-      <form className="signup-form" onSubmit={handleSubmit(this.props.signUpUser.bind(this))}>
+    <form className="signup-form" onSubmit={handleSubmit(props.signUpUser.bind(this))}>
       <p className="signup-form__field">
         <label className="signup-form__username-label" htmlFor="username">Username:</label>
         <input
@@ -54,6 +53,16 @@ class SignupForm extends React.Component {
     </form>
   );
 }
-}
+
+SignupForm.propTypes = {
+  fields: PropTypes.shape({
+    username: PropTypes.string.isRequired,
+    email: PropTypes.string.isRequired,
+    password: PropTypes.string.isRequired,
+    confirmPassword: PropTypes.string.isRequired
+  }).isRequired,
+  handleSubmit: PropTypes.func.isRequired,
+  signUpUser: PropTypes.func.isRequired
+};
 
 export default SignupForm;