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java-team-github-botError Prone Team
java-team-github-bot
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Error Prone Team
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Discourage public Foo stream() where Foo does _not_ end with "Stream"
PiperOrigin-RevId: 390684609
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‎core/src/main/java/com/google/errorprone/bugpatterns/PublicApiNamedStreamShouldReturnStream.java‎

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/*
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* Copyright 2021 Google Inc. All Rights Reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.errorprone.bugpatterns;
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import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
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import static com.google.errorprone.matchers.Matchers.allOf;
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import static com.google.errorprone.matchers.Matchers.methodHasVisibility;
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import static com.google.errorprone.matchers.Matchers.methodIsNamed;
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import com.google.errorprone.BugPattern;
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import com.google.errorprone.VisitorState;
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import com.google.errorprone.bugpatterns.BugChecker.MethodTreeMatcher;
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import com.google.errorprone.matchers.Description;
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import com.google.errorprone.matchers.Matcher;
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import com.google.errorprone.matchers.MethodVisibility;
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import com.google.errorprone.util.ASTHelpers;
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import com.sun.source.tree.MethodTree;
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import com.sun.tools.javac.code.Type;
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/**
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* Checks if public APIs named "stream" returns a type whose name ends with Stream.
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*
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* @author sauravtiwary@google.com (Saurav Tiwary)
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*/
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@BugPattern(
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name = "PublicApiNamedStreamShouldReturnStream",
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summary =
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"Public methods named stream() are generally expected to return a type whose name ends with"
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+ " Stream. Consider choosing a different method name instead.",
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severity = SUGGESTION)
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public class PublicApiNamedStreamShouldReturnStream extends BugChecker
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implements MethodTreeMatcher {
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private static final String STREAM = "stream";
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private static final Matcher<MethodTree> CONFUSING_PUBLIC_API_STREAM_MATCHER =
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allOf(
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methodIsNamed(STREAM),
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methodHasVisibility(MethodVisibility.Visibility.PUBLIC),
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PublicApiNamedStreamShouldReturnStream::returnTypeDoesNotEndsWithStream);
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private static boolean returnTypeDoesNotEndsWithStream(
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MethodTree methodTree, VisitorState state) {
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Type returnType = ASTHelpers.getSymbol(methodTree).getReturnType();
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// Constructors have no return type.
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return returnType != null && !returnType.tsym.getSimpleName().toString().endsWith("Stream");
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}
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@Override
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public Description matchMethod(MethodTree tree, VisitorState state) {
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if (!CONFUSING_PUBLIC_API_STREAM_MATCHER.matches(tree, state)) {
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return Description.NO_MATCH;
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}
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return describeMatch(tree);
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}
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}

‎core/src/main/java/com/google/errorprone/scanner/BuiltInCheckerSuppliers.java‎

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import com.google.errorprone.bugpatterns.ProtoTruthMixedDescriptors;
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import com.google.errorprone.bugpatterns.ProtocolBufferOrdinal;
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import com.google.errorprone.bugpatterns.ProtosAsKeyOfSetOrMap;
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import com.google.errorprone.bugpatterns.PublicApiNamedStreamShouldReturnStream;
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import com.google.errorprone.bugpatterns.PublicConstructorForAbstractClass;
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import com.google.errorprone.bugpatterns.RandomCast;
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import com.google.errorprone.bugpatterns.RandomModInteger;
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PrivateConstructorForNoninstantiableModule.class,
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PrivateConstructorForUtilityClass.class,
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ProtosAsKeyOfSetOrMap.class,
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PublicApiNamedStreamShouldReturnStream.class,
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PublicConstructorForAbstractClass.class,
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QualifierWithTypeUse.class,
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RedundantCondition.class,

‎core/src/test/java/com/google/errorprone/bugpatterns/PublicApiNamedStreamShouldReturnStreamTest.java‎

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/*
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* Copyright 2021 Google Inc. All Rights Reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.errorprone.bugpatterns;
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import com.google.errorprone.CompilationTestHelper;
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import org.junit.Before;
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import org.junit.Test;
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import org.junit.runner.RunWith;
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import org.junit.runners.JUnit4;
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/** Unit tests for {@link PublicApiNamedStreamShouldReturnStream}. */
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@RunWith(JUnit4.class)
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public class PublicApiNamedStreamShouldReturnStreamTest {
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private CompilationTestHelper compilationHelper;
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@Before
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public void setup() {
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compilationHelper =
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CompilationTestHelper.newInstance(PublicApiNamedStreamShouldReturnStream.class, getClass());
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}
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@Test
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public void abstractMethodPositiveCase() {
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compilationHelper
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.addSourceLines(
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"in/Test.java",
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"public abstract class Test {",
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" // BUG: Diagnostic contains: PublicApiNamedStreamShouldReturnStream",
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" public abstract int stream();",
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"}")
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.doTest();
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}
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@Test
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public void regularMethodPositiveCase() {
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compilationHelper
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.addSourceLines(
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"in/Test.java",
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"public class Test {",
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" // BUG: Diagnostic contains: PublicApiNamedStreamShouldReturnStream",
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" public String stream() { return \"hello\";}",
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"}")
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.doTest();
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}
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@Test
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public void compliantNegativeCase() {
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compilationHelper
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.addSourceLines(
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"in/Test.java",
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"import java.util.stream.Stream;",
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"public abstract class Test {",
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" public abstract Stream<Integer> stream();",
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"}")
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.doTest();
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}
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@Test
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public void differentNameNegativeCase() {
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compilationHelper
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.addSourceLines(
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"in/Test.java",
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"public class Test {",
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" public int differentMethodName() { return 0; }",
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"}")
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.doTest();
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}
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@Test
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public void privateMethodNegativeCase() {
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compilationHelper
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.addSourceLines(
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"in/Test.java",
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"public class Test {",
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" private String stream() { return \"hello\"; }",
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"}")
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.doTest();
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}
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@Test
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public void returnTypeEndingWithStreamNegativeCase() {
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compilationHelper
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.addSourceLines(
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"in/Test.java",
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"public class Test {",
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" private static class TestStream {}",
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" public TestStream stream() { return new TestStream(); }",
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"}")
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.doTest();
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}
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@Test
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public void returnTypeNotEndingWithStreamPositiveCase() {
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compilationHelper
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.addSourceLines(
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"in/Test.java",
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"public class Test {",
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" private static class TestStreamRandomSuffix {}",
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" // BUG: Diagnostic contains: PublicApiNamedStreamShouldReturnStream",
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" public TestStreamRandomSuffix stream() { return new TestStreamRandomSuffix(); }",
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"}")
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.doTest();
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}
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}

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