diff --git a/generators/test-generator/tests/org/jetbrains/kotlin/generators/tests/generator/TestGenerationDSL.kt b/generators/test-generator/tests/org/jetbrains/kotlin/generators/tests/generator/TestGenerationDSL.kt
index c9cdfe52559..f04b41b6f81 100644
--- a/generators/test-generator/tests/org/jetbrains/kotlin/generators/tests/generator/TestGenerationDSL.kt
+++ b/generators/test-generator/tests/org/jetbrains/kotlin/generators/tests/generator/TestGenerationDSL.kt
@@ -1,17 +1,6 @@
 /*
- * Copyright 2010-2017 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
 package org.jetbrains.kotlin.generators.tests.generator
@@ -19,28 +8,27 @@ package org.jetbrains.kotlin.generators.tests.generator
 import junit.framework.TestCase
 import org.jetbrains.kotlin.test.TargetBackend
 import java.io.File
-import java.lang.IllegalArgumentException
 import java.util.*
 import java.util.regex.Pattern
 
 class TestGroup(private val testsRoot: String, val testDataRoot: String, val testRunnerMethodName: String) {
-    inline fun <reified T: TestCase> testClass(
-            suiteTestClassName: String = getDefaultSuiteTestClassName(T::class.java.simpleName),
-            noinline init: TestClass.() -> Unit
+    inline fun <reified T : TestCase> testClass(
+        suiteTestClassName: String = getDefaultSuiteTestClassName(T::class.java.simpleName),
+        noinline init: TestClass.() -> Unit
     ) {
         testClass(T::class.java.name, suiteTestClassName, init)
     }
 
     fun testClass(
-            baseTestClassName: String,
-            suiteTestClassName: String = getDefaultSuiteTestClassName(baseTestClassName.substringAfterLast('.')),
-            init: TestClass.() -> Unit
+        baseTestClassName: String,
+        suiteTestClassName: String = getDefaultSuiteTestClassName(baseTestClassName.substringAfterLast('.')),
+        init: TestClass.() -> Unit
     ) {
         TestGenerator(
-                testsRoot,
-                suiteTestClassName,
-                baseTestClassName,
-                TestClass().apply(init).testModels
+            testsRoot,
+            suiteTestClassName,
+            baseTestClassName,
+            TestClass().apply(init).testModels
         ).generateAndSave()
     }
 
@@ -48,45 +36,51 @@ class TestGroup(private val testsRoot: String, val testDataRoot: String, val tes
         val testModels = ArrayList<TestClassModel>()
 
         fun model(
-                relativeRootPath: String,
-                recursive: Boolean = true,
-                excludeParentDirs: Boolean = false,
-                extension: String? = "kt", // null string means dir (name without dot)
-                pattern: String = if (extension == null) """^([^\.]+)$""" else "^(.+)\\.$extension\$",
-                testMethod: String = "doTest",
-                singleClass: Boolean = false,
-                testClassName: String? = null,
-                targetBackend: TargetBackend = TargetBackend.ANY,
-                excludeDirs: List<String> = listOf(),
-                filenameStartsLowerCase: Boolean? = null,
-                skipIgnored: Boolean = false
+            relativeRootPath: String,
+            recursive: Boolean = true,
+            excludeParentDirs: Boolean = false,
+            extension: String? = "kt", // null string means dir (name without dot)
+            pattern: String = if (extension == null) """^([^\.]+)$""" else "^(.+)\\.$extension\$",
+            testMethod: String = "doTest",
+            singleClass: Boolean = false,
+            testClassName: String? = null,
+            targetBackend: TargetBackend = TargetBackend.ANY,
+            excludeDirs: List<String> = listOf(),
+            filenameStartsLowerCase: Boolean? = null,
+            skipIgnored: Boolean = false
         ) {
-            val rootFile = File(testDataRoot + "/" + relativeRootPath)
+            val rootFile = File("$testDataRoot/$relativeRootPath")
             val compiledPattern = Pattern.compile(pattern)
             val className = testClassName ?: TestGeneratorUtil.fileNameToJavaIdentifier(rootFile)
             testModels.add(
-                    if (singleClass) {
-                        if (excludeDirs.isNotEmpty()) error("excludeDirs is unsupported for SingleClassTestModel yet")
-                        SingleClassTestModel(rootFile, compiledPattern, filenameStartsLowerCase, testMethod, className, targetBackend,
-                                             skipIgnored, testRunnerMethodName)
-                    }
-                    else {
-                        SimpleTestClassModel(rootFile, recursive, excludeParentDirs,
-                                             compiledPattern, filenameStartsLowerCase, testMethod, className,
-                                             targetBackend, excludeDirs, skipIgnored, testRunnerMethodName)
-                    }
+                if (singleClass) {
+                    if (excludeDirs.isNotEmpty()) error("excludeDirs is unsupported for SingleClassTestModel yet")
+                    SingleClassTestModel(
+                        rootFile, compiledPattern, filenameStartsLowerCase, testMethod, className, targetBackend,
+                        skipIgnored, testRunnerMethodName
+                    )
+                } else {
+                    SimpleTestClassModel(
+                        rootFile, recursive, excludeParentDirs,
+                        compiledPattern, filenameStartsLowerCase, testMethod, className,
+                        targetBackend, excludeDirs, skipIgnored, testRunnerMethodName
+                    )
+                }
             )
         }
     }
 }
 
-fun testGroup(testsRoot: String, testDataRoot: String, testRunnerMethodName: String = RunTestMethodModel.METHOD_NAME, init: TestGroup.() -> Unit) {
+fun testGroup(
+    testsRoot: String,
+    testDataRoot: String,
+    testRunnerMethodName: String = RunTestMethodModel.METHOD_NAME,
+    init: TestGroup.() -> Unit
+) {
     TestGroup(testsRoot, testDataRoot, testRunnerMethodName).init()
 }
 
 fun getDefaultSuiteTestClassName(baseTestClassName: String): String {
-    if (!baseTestClassName.startsWith("Abstract")) {
-        throw IllegalArgumentException("Doesn't start with \"Abstract\": $baseTestClassName")
-    }
+    require(baseTestClassName.startsWith("Abstract")) { "Doesn't start with \"Abstract\": $baseTestClassName" }
     return baseTestClassName.substringAfter("Abstract") + "Generated"
 }