[extract method] allow to extract a lambda expression with an assignment inside (IDEA-347866)

GitOrigin-RevId: 4258330bf27d70e942dc84d53c62842ac682fba4

java/java-impl-refactorings/src/com/intellij/refactoring/extractMethod/newImpl/ExtractSelector.kt

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+// Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.intellij.refactoring.extractMethod.newImpl
 
 import com.intellij.codeInsight.CodeInsightUtil
@@ -90,7 +90,14 @@ class ExtractSelector {
   }
 
   private fun hasAssignmentInside(expression: PsiExpression): Boolean {
-    return PsiTreeUtil.findChildOfType(expression, PsiAssignmentExpression::class.java, false) != null
+    val assignment = PsiTreeUtil.findChildOfType(expression, PsiAssignmentExpression::class.java, false)
+    if (assignment == null) return false
+    val lhs = assignment.lExpression
+    if (lhs is PsiReferenceExpression) {
+      val target = lhs.resolve()
+      return target != null && !expression.textRange.contains(target.textRange)
+    }
+    return false
   }
 
   private fun alignStatements(statements: List<PsiElement>): List<PsiElement> {

java/java-tests/testData/refactoring/extractMethodNew/AssignmentInsideLambda.java

@@ -0,0 +1,23 @@
+class AssignmentInsideLamda {
+
+  private final List<Comparator<String>> comparators = new ArrayList<>();
+
+  public void test(String[] args) {
+    Arrays.sort(args, <selection>(o1, o2) -> {
+      int result = compareForNull(o1, o2);
+      if (result == 0) {
+        for (Comparator<String> comparator : comparators) {
+          result = comparator.compare(o1, o2);
+          if (result != 0) {
+            return result;
+          }
+        }
+      }
+      return result;
+    }</selection>);
+  }
+
+  private int compareForNull(String o1, String o2) {
+    return 0;
+  }
+}

java/java-tests/testData/refactoring/extractMethodNew/AssignmentInsideLambda_after.java

@@ -0,0 +1,29 @@
+import org.jetbrains.annotations.NotNull;
+
+class AssignmentInsideLamda {
+
+  private final List<Comparator<String>> comparators = new ArrayList<>();
+
+  public void test(String[] args) {
+    Arrays.sort(args, newMethod());
+  }
+
+    private @NotNull Object newMethod() {
+        return (o1, o2) -> {
+            int result = compareForNull(o1, o2);
+            if (result == 0) {
+                for (Comparator<String> comparator : comparators) {
+                    result = comparator.compare(o1, o2);
+                    if (result != 0) {
+                        return result;
+                    }
+                }
+            }
+            return result;
+        };
+    }
+
+    private int compareForNull(String o1, String o2) {
+    return 0;
+  }
+}

java/java-tests/testSrc/com/intellij/java/refactoring/ExtractMethodNewTest.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2021 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.intellij.java.refactoring;
 
 import com.intellij.JavaTestUtil;
@@ -285,6 +285,10 @@ public class ExtractMethodNewTest extends LightJavaCodeInsightTestCase {
     }
   }
 
+  public void testAssignmentInsideLambda() throws Exception {
+    doTest();
+  }
+
   public void testExtractFromTryFinally2() throws Exception {
     doTest();
   }