invert boolean: leave expressions with unused return value untouched (IDEA-56568 )

java/java-impl/src/com/intellij/refactoring/invertBoolean/InvertBooleanProcessor.java

@@ -233,7 +233,9 @@ public class InvertBooleanProcessor extends BaseRefactoringProcessor {
                  ((PsiPrefixExpression)expression.getParent()).getOperationSign().getTokenType() == JavaTokenType.EXCL) {
             expression = (PsiExpression)expression.getParent();
           }
-          expression.replace(CodeInsightServicesUtil.invertCondition(expression));
+          if (!(expression.getParent() instanceof PsiExpressionStatement)) {
+            expression.replace(CodeInsightServicesUtil.invertCondition(expression));
+          }
         }
         catch (IncorrectOperationException e) {
           LOG.error(e);

java/java-tests/testData/refactoring/invertBoolean/unusedReturnValue.java

@@ -0,0 +1,9 @@
+class C {
+  boolean f<caret>oo() {
+    return false;
+  }
+
+  void bar() {
+    foo();
+  }
+}

java/java-tests/testData/refactoring/invertBoolean/unusedReturnValue_after.java

@@ -0,0 +1,9 @@
+class C {
+  boolean fooInverted() {
+    return true;
+  }
+
+  void bar() {
+    fooInverted();
+  }
+}

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

@@ -25,6 +25,7 @@ public class InvertBooleanTest extends LightCodeInsightTestCase {
   public void testParameter() throws Exception { doTest(); } //inverting boolean parameter
 
   public void testParameter1() throws Exception { doTest(); } //inverting boolean parameter more advanced stuff
+  public void testUnusedReturnValue() throws Exception { doTest(); }
 
   private void doTest() throws Exception {
     configureByFile(TEST_ROOT + getTestName(true) + ".java");