eclipse/xtext-core#253 Document testing API.

- Add documentation about testing custom generators using the
CompilationTestHelper utility class.
- Add documentation about automated UI testing using the abstract base
classes in the org.eclipse.xtext.ui.testing package.

Signed-off-by: Tamas Miklossy <miklossy@itemis.de>

xtext-website/documentation/103_domainmodelnextsteps.md

@@ -339,7 +339,39 @@ This tutorial is about testing the parser, the linker and the validator for the
     }
     ```
 
-3.  After saving the Xtend file, it is time to run the test. Select *Run As → JUnit Test* from the editor's context menu.
+3. The [CompilationTestHelper]({{site.src.xtext_extras}}/org.eclipse.xtext.xbase.testing/src/org/eclipse/xtext/xbase/testing/CompilationTestHelper.java) utility class comes in handy while unit testing the custom generator implementations:
+
+	```xtend
+	@Inject extension CompilationTestHelper
+
+	@Test def test() {
+		'''
+			datatype String
+			
+			package my.company.blog {
+				entity Blog {
+					title: String
+				}
+			}
+		'''.assertCompilesTo('''
+			package my.company.blog;
+
+			public class Blog {
+				private String title;
+				
+				public String getTitle() {
+					return title;
+				}
+				
+				public void setTitle(String title) {
+					this.title = title;
+				}
+			}
+		''')
+		}
+```
+
+4.  After saving the Xtend file, it is time to run the tests. Select *Run As → JUnit Test* from the editor's context menu.
 
 These tests serve only as a starting point and can be extended to cover the different features of the language. As a small exercise, you could implement e.g. test cases for the `checkFeatureNameIsUnique` validation rule. You can find more examples in the example projects shipped with the Xtext Framework. Simply go to *File → New → Example → Xtext Examples*.
 

xtext-website/documentation/310_eclipse_support.md

@@ -781,6 +781,22 @@ The base class `AbstractXtextCodeMiningProvider` provides some factory methods f
 
 For an implementation reference, have a look at the Xtext Domainmodel example.
 
+## UI Testing {#ui-testing}
+
+Automated UI tests are crucial for the maintainability and the quality of a software product. That's why it is strongly recommended to write not only automated unit tests for your language, but also automated UI tests for your language editor. The `org.eclipse.xtext.ui.testing` package contains some base classes that come in handy when implementing automated UI tests: 
+
+*	[AbstractAutoEditTest]({{site.src.xtext_eclipse}}/org.eclipse.xtext.ui.testing/src/org/eclipse/xtext/ui/testing/AbstractAutoEditTest.java): base class for testing the auto editing functionality
+*	[AbstractContentAssistTest]({{site.src.xtext_eclipse}}/org.eclipse.xtext.ui.testing/src/org/eclipse/xtext/ui/testing/AbstractContentAssistTest.xtend): base class for testing the content assistant and template proposals
+*	[AbstractFoldingTest]({{site.src.xtext_eclipse}}/org.eclipse.xtext.ui.testing/src/org/eclipse/xtext/ui/testing/AbstractFoldingTest.xtend): base class for testing the folding capabilities
+*	[AbstractHighlightingTest]({{site.src.xtext_eclipse}}/org.eclipse.xtext.ui.testing/src/org/eclipse/xtext/ui/testing/AbstractHighlightingTest.xtend): base class for testing the syntactical and semantic coloring
+*	[AbstractHoverTest]({{site.src.xtext_eclipse}}/org.eclipse.xtext.ui.testing/src/org/eclipse/xtext/ui/testing/AbstractHoverTest.xtend): base class for testing the hovering functionality
+*	[AbstractHyperlinkingTest]({{site.src.xtext_eclipse}}/org.eclipse.xtext.ui.testing/src/org/eclipse/xtext/ui/testing/AbstractHyperlinkingTest.xtend): base class for testing the hyperlinking functionality
+*	[AbstractOutlineTest]({{site.src.xtext_eclipse}}/org.eclipse.xtext.ui.testing/src/org/eclipse/xtext/ui/testing/AbstractOutlineTest.java): base class for testing the structure of the outline view
+*	[AbstractQuickfixTest]({{site.src.xtext_eclipse}}/org.eclipse.xtext.ui.testing/src/org/eclipse/xtext/ui/testing/AbstractQuickfixTest.xtend): base class for testing the quick fixes
+*	...
+
+The Xtext example projects (*File &rarr; New &rarr; Example &rarr; Xtext Examples*) contain UI test cases that make use of these framework classes. Feel free to study the corresponding `org.eclipse.xtext.example.<language>.ui.tests` projects to get some inspirations on how to implement automated UI test cases for your Xtext-based language editor.
+
 ---
 
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