JSF update managed bean with ServletContext listener for testing - jsf

Question

In a JSF 2.2 application, I want to build a war file for testing with Selenium. In that webtest.war, I want to replace a central class, called the NodeCache, with a mock version, called the WebtestNodeCache, to keep the database and other external dependencies out of the tests.
NodeCache is a managed bean:
#javax.faces.bean.ManagedBean(name = NodeCache.INSTANCE)
#javax.faces.bean.ApplicationScoped
public class NodeCache {
public static final String INSTANE = "nodecache";
// ...
}
To sneak in WebtestNodeCache, I use a ServletContextListener like this:
public class WebtestContextListener implements ServletContextListener {
#Override
public void contextInitialized(ServletContextEvent event) {
WebtestNodeCache nodeCache = new WebtestNodeCache();
ServletContext context = event.getServletContext();
context.setAttribute(NodeCache.INSTANCE, nodeCache);
}
#Override
public void contextDestroyed(ServletContextEvent sce) {}
}
In normal builds, WebtestContextListener and WebtestNodeCache are excluded from the war file, in test builds, they are included.
This seems to work: when I log in, I get dummy nodes from the WebtestNodeCache.
Is this a reliable way to replace a bean in application context or did I just get lucky?
Is there a better way to sneak in test dummies?

Answer 1

Using both an #ManagedBean annotation and a Listener to replace the object did not work. The code was always using the unmocked production code managed bean.
Defining a new #ManagedBean with the same name is an error and prevents deployment.
I ended up with this:
Put the #ManagedBean annotation with the same name on both the real bean and its mock.
When building, only include the mocks when building the webtest.war, but not in the regular build.
When building, have the build script (Gradle in my case) copy and filter the sources, looking for a special comment behind the #ManagedBean declaration in the production code and taking out these lines to remove the #ManagedBean declaration on the production code so that only the ones in the mock remains.
So the original NodeCache looks like this now:
#javax.faces.bean.ManagedBean(name = NodeCache.INSTANCE) // webtest:remove
#javax.faces.bean.ApplicationScoped // webtest:remove
public class NodeCache {
public static final String INSTANE = "nodecache";
// ...
}
and the mocked version has the same annotations, just without the comment:
#javax.faces.bean.ManagedBean(name = NodeCache.INSTANCE)
#javax.faces.bean.ApplicationScoped
public class WebtestNodeCache extends NodeCache {
// ...
}
Here is the relevant part of the Gradle build script:
boolean isWebtest = false
gradle.taskGraph.whenReady { taskGraph ->
isWebtest = taskGraph.hasTask(compileWebtestWarJava);
}
task copySrc(type: Copy) {
from "src"
into "${buildDir}/src"
outputs.upToDateWhen {
// Always execute this task so that resources do or don't get filtered
// when switching between normal war file and webtests.
false
}
filter { String line ->
isWebtest && line.contains("webtest:remove") ? null : line;
}
}
This solves the problem for me. Hope someone else finds it useful.