extract method suggester: unique parameter names (IDEA-152334); update output variables when suggester replaces the initial method

java/java-impl/src/com/intellij/refactoring/extractMethod/ExtractMethodProcessor.java

@@ -1728,6 +1728,22 @@ public class ExtractMethodProcessor implements MatchProvider {
         myExtractedMethod = suggester.getExtractedMethod();
         myMethodCall      = suggester.getMethodCall();
         myVariableDatum   = suggester.getVariableData();
+
+        final List<PsiVariable> outputVariables = new ArrayList<>();
+        for (PsiReturnStatement statement : PsiUtil.findReturnStatements(myExtractedMethod)) {
+          final PsiExpression returnValue = statement.getReturnValue();
+          if (returnValue instanceof PsiReferenceExpression) {
+            final PsiElement resolve = ((PsiReferenceExpression)returnValue).resolve();
+            if (resolve instanceof PsiLocalVariable) {
+              outputVariables.add((PsiVariable)resolve);
+            }
+          }
+        }
+
+        if (outputVariables.size() == 1) {
+          myOutputVariable = outputVariables.get(0);
+        }
+
         return null;
       }
     }

java/java-impl/src/com/intellij/refactoring/extractMethod/ExtractMethodSignatureSuggester.java

@@ -334,6 +334,12 @@ public class ExtractMethodSignatureSuggester {
     for (PsiParameter parameter : parameters) {
       uniqueNameGenerator.addExistingName(parameter.getName());
     }
+
+    SyntaxTraverser.psiTraverser().withRoot(myExtractedMethod.getBody())
+      .filter(element -> element instanceof PsiVariable)
+      .forEach(element -> uniqueNameGenerator.addExistingName(((PsiVariable)element).getName()));
+
+    
     final THashMap<PsiExpression, String> unique = new THashMap<PsiExpression, String>(ourEquivalenceStrategy);
     final Map<PsiExpression, String> replacement = new HashMap<PsiExpression, String>();
     for (PsiExpression expr : exprs) {

java/java-tests/testData/refactoring/extractMethod/SuggestChangeSignatureWithOutputVariables.java

@@ -0,0 +1,25 @@
+
+class Test {
+
+  private BigDecimal getRevenue() {
+    <selection>final String query = createNamedQuery("revenues");
+    String revenues = "";
+    final String revenue;
+    revenue = "a";
+    </selection>
+    return revenue;
+  }
+
+  public BigDecimal getExpense() {
+    final String query = createNamedQuery("expenses");
+    String expenses = "";
+    final String expense;
+    expense = "a";
+
+    return expense;
+  }
+
+  private String createNamedQuery(String expenses) {
+    return null;
+  }
+}

java/java-tests/testData/refactoring/extractMethod/SuggestChangeSignatureWithOutputVariables_after.java

@@ -0,0 +1,29 @@
+import org.jetbrains.annotations.NotNull;
+
+class Test {
+
+  private BigDecimal getRevenue() {
+      final String revenue = newMethod("revenues");
+    
+    return revenue;
+  }
+
+    @NotNull
+    private String newMethod(String revenues2) {
+        final String query = createNamedQuery(revenues2);
+        String revenues = "";
+        final String revenue;
+        revenue = "a";
+        return revenue;
+    }
+
+    public BigDecimal getExpense() {
+        final String expense = newMethod("expenses");
+
+    return expense;
+  }
+
+  private String createNamedQuery(String expenses) {
+    return null;
+  }
+}

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

@@ -675,6 +675,10 @@ public class ExtractMethodTest extends LightCodeInsightTestCase {
     doDuplicatesTest();
   }
 
+  public void testSuggestChangeSignatureWithOutputVariables() throws Exception {
+    doDuplicatesTest();
+  }
+
   public void testSuggestChangeSignatureWithChangedParameterName() throws Exception {
     configureByFile(BASE_PATH + getTestName(false) + ".java");
     boolean success = performExtractMethod(true, true, getEditor(), getFile(), getProject(), false, null, false, "p");