KT-18006 Don't cut off trailing new lines. Make behavior consistent with Java literal copy/paste

idea/src/org/jetbrains/kotlin/idea/editor/KotlinLiteralCopyPasteProcessor.kt

@@ -135,14 +135,21 @@ class KotlinLiteralCopyPasteProcessor : CopyPastePreProcessor {
 
         return if (beginTp.isSingleQuoted()) {
             val res = StringBuilder()
+            val lineBreak = "\\n\"+\n \""
+            var endsInLineBreak = false
             TemplateTokenSequence(text).forEach {
                 when (it) {
                     is LiteralChunk -> StringUtil.escapeStringCharacters(it.text.length, it.text, "\$\"", res)
                     is EntryChunk -> res.append(it.text)
-                    is NewLineChunk -> res.append("\\n\"+\n \"")
+                    is NewLineChunk -> res.append(lineBreak)
                 }
+                endsInLineBreak = it is NewLineChunk
+            }
+            return if (endsInLineBreak){
+                res.removeSuffix(lineBreak).toString() + "\\n"
+            } else{
+                res.toString()
             }
-            res.toString()
         }
         else {
             val tripleQuoteRe = Regex("[\"]{3,}")
@@ -211,7 +218,7 @@ private class TemplateTokenSequence(private val inputString: String) : Sequence<
     }
 
     private suspend fun SequenceBuilder<TemplateChunk>.yieldLiteral(chunk: String) {
-        val splitLines = LineTokenizer.tokenize(chunk, false, true)
+        val splitLines = LineTokenizer.tokenize(chunk, false, false)
         for (i in 0..splitLines.size - 1) {
             if (i != 0) {
                 yield(NewLineChunk)

idea/testData/copyPaste/plainTextLiteral/TrailingLines.expected.kt

@@ -0,0 +1,6 @@
+val a = "a\n" +
+        "b\n" +
+        "c\n" +
+        "\n" +
+        "\n" +
+        "\n"

idea/testData/copyPaste/plainTextLiteral/TrailingLines.kt

@@ -0,0 +1 @@
+val a = "<caret>"

idea/testData/copyPaste/plainTextLiteral/TrailingLines.txt

@@ -0,0 +1,10 @@
+<selection>a
+b
+c
+
+
+
+</selection>d
+e
+f
+g

idea/tests/org/jetbrains/kotlin/idea/conversion/copy/LiteralTextToKotlinCopyPasteTestGenerated.java

@@ -66,6 +66,12 @@ public class LiteralTextToKotlinCopyPasteTestGenerated extends AbstractLiteralTe
         doTest(fileName);
     }
 
+    @TestMetadata("TrailingLines.txt")
+    public void testTrailingLines() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("idea/testData/copyPaste/plainTextLiteral/TrailingLines.txt");
+        doTest(fileName);
+    }
+
     @TestMetadata("WithBackslashes.txt")
     public void testWithBackslashes() throws Exception {
         String fileName = KotlinTestUtils.navigationMetadata("idea/testData/copyPaste/plainTextLiteral/WithBackslashes.txt");

idea/tests/org/jetbrains/kotlin/idea/editor/AbstractLiteralTextToKotlinCopyPasteTest.kt

@@ -38,7 +38,8 @@ abstract class AbstractLiteralTextToKotlinCopyPasteTest : AbstractCopyPasteTest(
         myFixture.configureByFiles(testName + ".txt")
         val fileText = myFixture.editor.document.text
 
-        myFixture.editor.selectionModel.setSelection(0, fileText.length)
+        if (!myFixture.editor.selectionModel.hasSelection())
+            myFixture.editor.selectionModel.setSelection(0, fileText.length)
         myFixture.performEditorAction(IdeActions.ACTION_COPY)
 
         configureTargetFile(testName + ".kt")

idea/tests/org/jetbrains/kotlin/idea/editor/TemplateTokenSequenceTest.kt

@@ -44,7 +44,7 @@ class TemplateTokenSequenceTest:UsefulTestCase() {
 
     //last empty line is skipped
     fun `test trailing new lines`(){
-        doTest("literal\n\n", "LITERAL_CHUNK(literal)NEW_LINE()")
+        doTest("literal\n\n", "LITERAL_CHUNK(literal)NEW_LINE()NEW_LINE()")
 
     }