Add tests for JetRefactoringUtil.selectExpression

Add tests for JetRefactoringUtil.selectExpression, which is invoked by
e.g. extract variable when some text is selected.

Test cases under idea/testData/expressionSelection/ should contain
Kotlin files with the usual <selection> tags, with the expected result
of selectExpression in the last comment of the file.

generators/src/org/jetbrains/jet/generators/tests/GenerateTests.kt

@@ -95,6 +95,7 @@ import org.jetbrains.jet.checkers.AbstractJetDiagnosticsTestWithStdLib
 import org.jetbrains.jet.plugin.codeInsight.AbstractInsertImportOnPasteTest
 import org.jetbrains.jet.resolve.AbstractReferenceToJavaWithWrongFileStructureTest
 import org.jetbrains.jet.plugin.navigation.AbstractKotlinGotoTest
+import org.jetbrains.jet.plugin.AbstractExpressionSelectionTest
 
 fun main(args: Array<String>) {
     System.setProperty("java.awt.headless", "true")
@@ -483,6 +484,10 @@ fun main(args: Array<String>) {
         testClass(javaClass<AbstractSmartSelectionTest>()) {
             model("smartSelection", testMethod = "doTestSmartSelection", pattern = """^([^\.]+)\.kt$""")
         }
+
+        testClass(javaClass<AbstractExpressionSelectionTest>()) {
+            model("expressionSelection", testMethod = "doTestExpressionSelection", pattern = """^([^\.]+)\.kt$""")
+        }
     }
 
     testGroup("j2k/tests/test", "j2k/tests/testData") {