Circular view path [login]: would dispatch back to the current handler URL [/login] again.

Junit5でのテスト時に丸一日ハマっためも

javax.servlet.ServletException: Circular view path [login]: 
    would dispatch back to the current handler URL [/login] again. 
    Check your ViewResolver setup!
    (Hint: This may be the result of an unspecified view, due to default view name generation.)

以下方法で解決。 原因は理解できてない。 www.programmersought.com