Because on Jenkins this test is passed – changing fix version to Beta1.

There are no proposals because XHTMLTemplateContentAssistComputer hasn't been created yet.
After you open Window->Preferences->JBoss Tools->Editors->VPE->Code Templates to check that temlates are defined – and then after returning back to the page CA will show templates' proposals.

The reason is that org.jboss.tools.jst.web.ui plugin is not loaded yet. Thus extension point "org.eclipse.wst.sse.ui.completionProposal" hasn't been initiated yet -> no completion proposals are shown.

Such a behavior is a rule in Eclipse UI:

"A plug-in gets started when the user needs it. In UI design, an often cited rule is that the screen belongs to the user. A program should not make changes on the screen that the user didn’t somehow initiate." (c)

It explains the situation that after looking into "Code Templates" CA starts working
(or you can select "New JSF Wizard" -> CA will appear as well).

JUnit on Jenkins is not failing because before running this test org.jboss.tools.jst.web.ui plugin has been already accessed.
But localy there is a failure.

But there is a question why the extension point is not loaded from plugin.xml file (declarative section). The full plugin initialization is not required to use plugin.xml.

Actually there is an attribute "activate" in <proposalComputer> declaration which will force the plug-in to be loaded on content assist invocation.

Resolved.