492149: Explicit dependency on org.eclipse.rcp in ui.tests

If you have a ui test that needs the workbench or an editor, if you do
not have org.eclipse.osgi.compatibility.state, introduced in Luna, in
the dependencies the workbench and editors will be null and the UI tests
will fail. By adding org.eclipse.rcp feature as a dependency, then
org.eclipse.osgi.compatibility.state will be dragged in and UI tests
will work, since the workbench will be available.  Adding
org.eclipse.rcp is safe also for previous Eclipse target platforms,
while adding org.eclipse.osgi.compatibility.state only will not work in
Eclipse versions earlier than Luna.

At least, that's what I do to run UI tests that require the workbench.

Task-Url: https://bugs.eclipse.org/bugs/show_bug.cgi?id=492149

plugins/org.eclipse.xtext.xtext.wizard/src/org/eclipse/xtext/xtext/wizard/TestProjectDescriptor.xtend

@@ -85,6 +85,26 @@ abstract class TestProjectDescriptor extends ProjectDescriptor {
 									«ENDIF»
 								</configuration>
 							</plugin>
+							«IF needsUiHarness»
+							<plugin>
+								<groupId>org.eclipse.tycho</groupId>
+								<artifactId>target-platform-configuration</artifactId>
+								<configuration>
+									<dependency-resolution>
+										<extraRequirements>
+											<!-- to get the org.eclipse.osgi.compatibility.state plugin
+											if the target platform is Luna or later.
+											(backward compatible with kepler and previous versions) -->
+											<requirement>
+												<type>eclipse-feature</type>
+												<id>org.eclipse.rcp</id>
+												<versionRange>0.0.0</versionRange>
+											</requirement>
+										</extraRequirements>
+									</dependency-resolution>
+								</configuration>
+							</plugin>
+							«ENDIF»
 						«ENDIF»
 						«IF !isEclipsePluginProject»
 							<plugin>