Add tests for appending values to sequence operation

idea/tests/com/intellij/debugger/streams/kotlin/exec/sequence/AppendOperationsTest.kt

@@ -0,0 +1,13 @@
+// Copyright 2000-2017 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package com.intellij.debugger.streams.kotlin.exec.sequence
+
+/**
+ * @author Vitaliy.Bibaev
+ */
+class AppendOperationsTest : OperationsTestCase("append") {
+  fun testPlusSingle() = doTestWithResult()
+  fun testPlusArray() = doTestWithResult()
+  fun testPlusSequence() = doTestWithResult()
+
+  fun testPlusElement() = doTestWithResult()
+}