use class instead of id for identifying errorMsg in test

src/components/join-flow/registration-error-step.jsx

@@ -38,7 +38,7 @@ class RegistrationErrorStep extends React.Component {
                     <FormattedMessage id="registration.cantCreateAccount" />
                 </p>
                 {this.props.errorMsg && (
-                    <p className="join-flow-instructions" id="registration-error-msg">
+                    <p className="join-flow-instructions registration-error-msg">
                         {this.props.errorMsg}
                     </p>
                 )}

test/unit/components/registration-error-step.test.jsx

@@ -33,7 +33,7 @@ describe('RegistrationErrorStep', () => {
         };
         const joinFlowStepWrapper = getRegistrationErrorStepWrapper(props).find(JoinFlowStep);
         const joinFlowStepInstance = joinFlowStepWrapper.dive();
-        const errMsgElement = joinFlowStepInstance.find('#registration-error-msg');
+        const errMsgElement = joinFlowStepInstance.find('.registration-error-msg');
         expect(errMsgElement).toHaveLength(1);
         expect(errMsgElement.text()).toEqual('halp there is a errors!!');
     });
@@ -45,7 +45,7 @@ describe('RegistrationErrorStep', () => {
         };
         const joinFlowStepWrapper = getRegistrationErrorStepWrapper(props).find(JoinFlowStep);
         const joinFlowStepInstance = joinFlowStepWrapper.dive();
-        const errMsgElement = joinFlowStepInstance.find('#registration-error-msg');
+        const errMsgElement = joinFlowStepInstance.find('.registration-error-msg');
         expect(errMsgElement).toHaveLength(0);
     });