Evaluate parents of UAST elements lazily

Also add tests for UAST consistency in various cases

plugins/uast-kotlin/tests/AbstractKotlinRenderLogTest.kt

@@ -1,15 +1,18 @@
 package org.jetbrains.uast.test.kotlin
 
 import com.intellij.psi.PsiElement
+import com.intellij.psi.PsiRecursiveElementVisitor
 import org.jetbrains.kotlin.psi.KtFile
 import org.jetbrains.kotlin.utils.addToStdlib.assertedCast
 import org.jetbrains.uast.UDeclaration
 import org.jetbrains.uast.UElement
 import org.jetbrains.uast.UFile
-import org.jetbrains.uast.UIdentifier
+import org.jetbrains.uast.kotlin.KotlinUastLanguagePlugin
 import org.jetbrains.uast.test.common.RenderLogTestBase
 import org.jetbrains.uast.visitor.UastVisitor
+import org.junit.Assert
 import java.io.File
+import java.util.*
 
 abstract class AbstractKotlinRenderLogTest : AbstractKotlinUastTest(), RenderLogTestBase {
     override fun getTestFile(testName: String, ext: String) =
@@ -17,6 +20,34 @@ abstract class AbstractKotlinRenderLogTest : AbstractKotlinUastTest(), RenderLog
 
     override fun check(testName: String, file: UFile) {
         super.check(testName, file)
+
+        file.psi.accept(object : PsiRecursiveElementVisitor() {
+            override fun visitElement(element: PsiElement) {
+                KotlinUastLanguagePlugin().convertElementWithParent(element, null)
+                super.visitElement(element)
+            }
+        })
+
+        file.accept(object : UastVisitor {
+            private val parentStack = Stack<UElement>()
+
+            override fun visitElement(node: UElement): Boolean {
+                val parent = node.uastParent
+                if (parent == null) {
+                    Assert.assertTrue("Wrong parent of $node", parentStack.empty())
+                }
+                else {
+                    Assert.assertEquals("Wrong parent of $node", parentStack.peek(), parent)
+                }
+                parentStack.push(node)
+                return false
+            }
+
+            override fun afterVisitElement(node: UElement) {
+                super.afterVisitElement(node)
+                parentStack.pop()
+            }
+        })
         file.checkContainingFileForAllElements()
     }
 
@@ -36,4 +67,4 @@ abstract class AbstractKotlinRenderLogTest : AbstractKotlinUastTest(), RenderLog
             }
         })
     }
-}
+}