"Replace if with when": Do not remove block braces if block has single lambda expression #KT-26187 Fixed

idea/src/org/jetbrains/kotlin/idea/intentions/branchedTransformations/IfThenUtils.kt

@@ -69,7 +69,9 @@ fun KtExpression.unwrapBlockOrParenthesis(): KtExpression {
     val innerExpression = KtPsiUtil.safeDeparenthesize(this, true)
     if (innerExpression is KtBlockExpression) {
         val statement = innerExpression.statements.singleOrNull() ?: return this
-        return KtPsiUtil.safeDeparenthesize(statement, true)
+        val deparenthesized = KtPsiUtil.safeDeparenthesize(statement, true)
+        if (deparenthesized is KtLambdaExpression) return this
+        return deparenthesized
     }
     return innerExpression
 }

idea/testData/intentions/branched/ifWhen/ifToWhen/lambdaExpression.kt

@@ -0,0 +1,9 @@
+fun test(x: Int) {
+    val f: Function<Int> = <caret>if (x == 0) {
+        { 0 }
+    } else if (x == 1) {
+        { 1 }
+    } else {
+        { 2 }
+    }
+}

idea/testData/intentions/branched/ifWhen/ifToWhen/lambdaExpression.kt.after

@@ -0,0 +1,13 @@
+fun test(x: Int) {
+    val f: Function<Int> = when (x) {
+        0 -> {
+            { 0 }
+        }
+        1 -> {
+            { 1 }
+        }
+        else -> {
+            { 2 }
+        }
+    }
+}

idea/testData/intentions/branched/ifWhen/ifToWhen/lambdaExpression2.kt

@@ -0,0 +1,9 @@
+fun test(x: Int) {
+    val f: Function<Int> = <caret>if (x == 0) {
+        ({ 0 })
+    } else if (x == 1) {
+        (({ 1 }))
+    } else {
+        ((({ 2 })))
+    }
+}

idea/testData/intentions/branched/ifWhen/ifToWhen/lambdaExpression2.kt.after

@@ -0,0 +1,13 @@
+fun test(x: Int) {
+    val f: Function<Int> = when (x) {
+        0 -> {
+            ({ 0 })
+        }
+        1 -> {
+            (({ 1 }))
+        }
+        else -> {
+            ((({ 2 })))
+        }
+    }
+}

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

@@ -2564,6 +2564,16 @@ public class IntentionTestGenerated extends AbstractIntentionTest {
                     runTest("idea/testData/intentions/branched/ifWhen/ifToWhen/ifWithoutElse.kt");
                 }
 
+                @TestMetadata("lambdaExpression.kt")
+                public void testLambdaExpression() throws Exception {
+                    runTest("idea/testData/intentions/branched/ifWhen/ifToWhen/lambdaExpression.kt");
+                }
+
+                @TestMetadata("lambdaExpression2.kt")
+                public void testLambdaExpression2() throws Exception {
+                    runTest("idea/testData/intentions/branched/ifWhen/ifToWhen/lambdaExpression2.kt");
+                }
+
                 @TestMetadata("multipleIfFake.kt")
                 public void testMultipleIfFake() throws Exception {
                     runTest("idea/testData/intentions/branched/ifWhen/ifToWhen/multipleIfFake.kt");