There is no reason to let test server when not all required fields are provided. It throws exceptions in log:
java.lang.RuntimeException: Cannot construct a server because all server properties are not valid at org.jboss.tools.modeshape.rest.wizards.ServerPage.getServer(ServerPage.java:357) at org.jboss.tools.modeshape.rest.wizards.ServerPage.handleTestConnection(ServerPage.java:389) at org.jboss.tools.modeshape.rest.wizards.ServerPage$5.widgetSelected(ServerPage.java:272) at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:234) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1258) at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3540) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3161) at org.eclipse.jface.window.Window.runEventLoop(Window.java:825) at org.eclipse.jface.window.Window.open(Window.java:801) at org.jboss.tools.modeshape.rest.actions.NewServerAction.run(NewServerAction.java:87) at org.eclipse.jface.action.Action.runWithEvent(Action.java:498) at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:584) at org.eclipse.jface.action.ActionContributionItem.access$2(ActionContributionItem.java:501) at org.eclipse.jface.action.ActionContributionItem$5.handleEvent(ActionContributionItem.java:411) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1258) at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3540) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3161) at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2640) at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2604) at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2438) at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:671) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332) at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:664) at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149) at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:115) at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:369) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:616) at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:619) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:574) at org.eclipse.equinox.launcher.Main.run(Main.java:1407)