Fix problem with appending literal to variable omitting braces #KT-13336 Fixed

idea/src/org/jetbrains/kotlin/idea/intentions/ConvertToStringTemplateIntention.kt

@@ -123,12 +123,19 @@ class ConvertToStringTemplateIntention : SelfTargetingOffsetIndependentIntention
                 else {
                     StringUtil.unquoteString(expressionText)
                 }
-                if (forceBraces && base.endsWith('$')) {
-                    return base.dropLast(1) + "\\$"
-                }
-                else {
-                    return base
+
+                if (forceBraces) {
+                    if (base.endsWith('$')) {
+                        return base.dropLast(1) + "\\$"
+                    }
+                    else {
+                        val lastPart = expression.children.lastOrNull()
+                        if (lastPart is KtSimpleNameStringTemplateEntry) {
+                            return base.dropLast(lastPart.textLength) + "\${" + lastPart.text.drop(1) + "}"
+                        }
+                    }
                 }
+                return base
             }
 
             is KtNameReferenceExpression ->

idea/testData/intentions/convertToStringTemplate/longTemplatePlusStringLiteral.kt

@@ -0,0 +1,4 @@
+fun foo() {
+    val nv1 = 1
+    val nv2 = "prefix $nv1" + <caret>"postfix"
+}

idea/testData/intentions/convertToStringTemplate/longTemplatePlusStringLiteral.kt.after

@@ -0,0 +1,4 @@
+fun foo() {
+    val nv1 = 1
+    val nv2 = "prefix ${nv1}postfix"
+}

idea/testData/intentions/convertToStringTemplate/stringPlusStringLiteral.kt

@@ -0,0 +1,4 @@
+fun foo() {
+    val prefix = "prefix"
+    val nv2 = prefix + <caret>"postfix"
+}

idea/testData/intentions/convertToStringTemplate/stringPlusStringLiteral.kt.after

@@ -0,0 +1,4 @@
+fun foo() {
+    val prefix = "prefix"
+    val nv2 = "${prefix}postfix"
+}

idea/testData/intentions/convertToStringTemplate/templatePlusStringLiteral.kt

@@ -0,0 +1,4 @@
+fun foo() {
+    val nv1 = 1
+    val nv2 = "$nv1" + <caret>"postfix"
+}

idea/testData/intentions/convertToStringTemplate/templatePlusStringLiteral.kt.after

@@ -0,0 +1,4 @@
+fun foo() {
+    val nv1 = 1
+    val nv2 = "${nv1}postfix"
+}

idea/tests/org/jetbrains/kotlin/idea/intentions/IntentionTestGenerated.java

@@ -5254,6 +5254,12 @@ public class IntentionTestGenerated extends AbstractIntentionTest {
             doTest(fileName);
         }
 
+        @TestMetadata("longTemplatePlusStringLiteral.kt")
+        public void testLongTemplatePlusStringLiteral() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/convertToStringTemplate/longTemplatePlusStringLiteral.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("multilineString.kt")
         public void testMultilineString() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/convertToStringTemplate/multilineString.kt");
@@ -5320,6 +5326,18 @@ public class IntentionTestGenerated extends AbstractIntentionTest {
             doTest(fileName);
         }
 
+        @TestMetadata("stringPlusStringLiteral.kt")
+        public void testStringPlusStringLiteral() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/convertToStringTemplate/stringPlusStringLiteral.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("templatePlusStringLiteral.kt")
+        public void testTemplatePlusStringLiteral() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/convertToStringTemplate/templatePlusStringLiteral.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("tricky.kt")
         public void testTricky() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/convertToStringTemplate/tricky.kt");