Add test for setState callback with no arguments.

Author: barakyosi

tests/lib/rules/no-unused-state.js

@@ -704,6 +704,18 @@ eslintTester.run('no-unused-state', rule, {
       }
       `,
       parser: 'babel-eslint'
+    }, {
+      // Don't error out
+      code: `
+      class Foo extends Component {
+        handleChange = function() {
+          this.setState(() => ({ foo: value }));
+        }
+        render() {
+          return <SomeComponent foo={this.state.foo} />;
+        }
+      }`,
+      parser: 'babel-eslint'
     }, {
       // Don't error out
       code: `