How to avoid the "Circular view path" exception with Spring MVC test

I solved this problem by using @ResponseBody like below:

@RequestMapping(value = "/resturl", method = RequestMethod.GET, produces = {"application/json"})
    @ResponseStatus(HttpStatus.OK)
    @Transactional(value = "jpaTransactionManager")
    public @ResponseBody List<DomainObject> findByResourceID(@PathParam("resourceID") String resourceID) {

@Controller → @RestController

I had the same issue and I noticed that my controller was also annotated with @Controller. Replacing it with @RestController solved the issue. Here is the explanation from Spring Web MVC:

@RestController is a composed annotation that is itself meta-annotated with @Controller and @ResponseBody indicating a controller whose every method inherits the type-level @ResponseBody annotation and therefore writes directly to the response body vs view resolution and rendering with an HTML template.

This has nothing to do with Spring MVC testing.

When you don't declare a ViewResolver, Spring registers a default InternalResourceViewResolver which creates instances of JstlView for rendering the View.

The JstlView class extends InternalResourceView which is

Wrapper for a JSP or other resource within the same web application. Exposes model objects as request attributes and forwards the request to the specified resource URL using a javax.servlet.RequestDispatcher.

A URL for this view is supposed to specify a resource within the web application, suitable for RequestDispatcher's forward or include method.

Emphasis mine. In other words, the view, before rendering, will try to get a RequestDispatcher to which to forward(). Before doing this it checks the following

if (path.startsWith("/") ? uri.equals(path) : uri.equals(StringUtils.applyRelativePath(uri, path))) {
    throw new ServletException("Circular view path [" + path + "]: would dispatch back " +
                        "to the current handler URL [" + uri + "] again. Check your ViewResolver setup! " +
                        "(Hint: This may be the result of an unspecified view, due to default view name generation.)");
}

where path is the view name, what you returned from the @Controller. In this example, that is preference. The variable uri holds the uri of the request being handled, which is /context/preference.

The code above realizes that if you were to forward to /context/preference, the same servlet (since the same handled the previous) would handle the request and you would go into an endless loop.

---

When you declare a ThymeleafViewResolver and a ServletContextTemplateResolver with a specific prefix and suffix, it builds the View differently, giving it a path like

WEB-INF/web-templates/preference.html

ThymeleafView instances locate the file relative to the ServletContext path by using a ServletContextResourceResolver

templateInputStream = resourceResolver.getResourceAsStream(templateProcessingParameters, resourceName);`

which eventually

return servletContext.getResourceAsStream(resourceName);

This gets a resource that is relative to the ServletContext path. It can then use the TemplateEngine to generate the HTML. There's no way an endless loop can happen here.