Add integration test case for refs that reproduces issue seen with

string refs.

integration-tests/react-percy/src/Refs.js

@@ -0,0 +1,41 @@
+import PropTypes from 'prop-types';
+import React from 'react';
+
+export default class Refs extends React.Component {
+  static propTypes = {
+    children: PropTypes.string.isRequired,
+    type: PropTypes.oneOf(['string', 'function', 'createRef']).isRequired,
+  };
+
+  ref = React.createRef();
+
+  render() {
+    switch (this.props.type) {
+      case 'string':
+        return (
+          // eslint-disable-next-line react/no-string-refs
+          <div ref="test">
+            {this.props.children}
+          </div>
+        );
+
+      case 'function':
+        return (
+          <div
+            ref={el => {
+              this.el = el;
+            }}
+          >
+            {this.props.children}
+          </div>
+        );
+
+      case 'createRef':
+        return (
+          <div ref={this.ref}>
+            {this.props.children}
+          </div>
+        );
+    }
+  }
+}

integration-tests/react-percy/src/__percy__/Refs.percy.js

@@ -0,0 +1,16 @@
+import React from 'react';
+import Refs from '../Refs';
+
+suite('Refs', () => {
+  percySnapshot('components with string refs work', () => {
+    return <Refs type="string">This is some text</Refs>;
+  });
+
+  percySnapshot('components with function refs work', () => {
+    return <Refs type="function">This is some text</Refs>;
+  });
+
+  percySnapshot('components using createRef work', () => {
+    return <Refs type="createRef">This is some text</Refs>;
+  });
+});