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Add Junit5 OutputCapture Extension
See gh-14738
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‎spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/extension/OutputCapture.java‎

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/*
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* Copyright 2012-2018 the original author or authors.
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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 org.springframework.boot.test.extension;
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import java.io.ByteArrayOutputStream;
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import java.io.IOException;
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import java.io.OutputStream;
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import java.io.PrintStream;
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import java.util.ArrayList;
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import java.util.List;
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import org.hamcrest.Matcher;
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import org.junit.Assert;
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import org.junit.jupiter.api.extension.AfterEachCallback;
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import org.junit.jupiter.api.extension.BeforeAllCallback;
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import org.junit.jupiter.api.extension.BeforeEachCallback;
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import org.junit.jupiter.api.extension.ExtensionContext;
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import org.junit.jupiter.api.extension.ParameterContext;
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import org.junit.jupiter.api.extension.ParameterResolutionException;
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import org.junit.jupiter.api.extension.ParameterResolver;
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import org.springframework.boot.ansi.AnsiOutput;
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import static org.hamcrest.Matchers.allOf;
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/**
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* JUnit5 {@code @Extension} to capture output from System.out and System.err.
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*
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* @author Madhura Bhave
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*/
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public class OutputCapture implements BeforeEachCallback, AfterEachCallback,
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BeforeAllCallback, ParameterResolver, CharSequence {
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private CaptureOutputStream captureOut;
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private CaptureOutputStream captureErr;
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private ByteArrayOutputStream methodLevelCopy;
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private ByteArrayOutputStream classLevelCopy;
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private List<Matcher<? super String>> matchers = new ArrayList<>();
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@Override
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public void afterEach(ExtensionContext context) {
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try {
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if (!this.matchers.isEmpty()) {
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String output = this.toString();
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Assert.assertThat(output, allOf(this.matchers));
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}
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}
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finally {
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releaseOutput();
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}
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}
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@Override
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public void beforeEach(ExtensionContext context) {
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releaseOutput();
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this.methodLevelCopy = new ByteArrayOutputStream();
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captureOutput(this.methodLevelCopy);
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}
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private void captureOutput(ByteArrayOutputStream copy) {
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AnsiOutputControl.get().disableAnsiOutput();
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this.captureOut = new CaptureOutputStream(System.out, copy);
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this.captureErr = new CaptureOutputStream(System.err, copy);
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System.setOut(new PrintStream(this.captureOut));
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System.setErr(new PrintStream(this.captureErr));
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}
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private void releaseOutput() {
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AnsiOutputControl.get().enabledAnsiOutput();
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System.setOut(this.captureOut.getOriginal());
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System.setErr(this.captureErr.getOriginal());
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this.methodLevelCopy = null;
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}
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private void flush() {
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try {
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this.captureOut.flush();
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this.captureErr.flush();
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}
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catch (IOException ex) {
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// ignore
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}
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}
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@Override
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public int length() {
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return this.toString().length();
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}
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@Override
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public char charAt(int index) {
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return this.toString().charAt(index);
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}
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@Override
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public CharSequence subSequence(int start, int end) {
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return this.toString().subSequence(start, end);
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}
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@Override
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public String toString() {
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flush();
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if (this.classLevelCopy == null && this.methodLevelCopy == null) {
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return "";
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}
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StringBuilder builder = new StringBuilder();
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if (this.classLevelCopy != null) {
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builder.append(this.classLevelCopy.toString());
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}
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builder.append(this.methodLevelCopy.toString());
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return builder.toString();
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}
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@Override
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public void beforeAll(ExtensionContext context) {
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this.classLevelCopy = new ByteArrayOutputStream();
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captureOutput(this.classLevelCopy);
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}
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@Override
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public boolean supportsParameter(ParameterContext parameterContext,
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ExtensionContext extensionContext) throws ParameterResolutionException {
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return OutputCapture.class.equals(parameterContext.getParameter().getType());
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}
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@Override
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public Object resolveParameter(ParameterContext parameterContext,
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ExtensionContext extensionContext) throws ParameterResolutionException {
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return this;
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}
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private static class CaptureOutputStream extends OutputStream {
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private final PrintStream original;
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private final OutputStream copy;
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CaptureOutputStream(PrintStream original, OutputStream copy) {
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this.original = original;
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this.copy = copy;
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}
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@Override
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public void write(int b) throws IOException {
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this.copy.write(b);
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this.original.write(b);
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this.original.flush();
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}
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@Override
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public void write(byte[] b) throws IOException {
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write(b, 0, b.length);
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}
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@Override
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public void write(byte[] b, int off, int len) throws IOException {
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this.copy.write(b, off, len);
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this.original.write(b, off, len);
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}
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public PrintStream getOriginal() {
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return this.original;
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}
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@Override
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public void flush() throws IOException {
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this.copy.flush();
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this.original.flush();
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}
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}
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/**
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* Allow AnsiOutput to not be on the test classpath.
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*/
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private static class AnsiOutputControl {
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public void disableAnsiOutput() {
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}
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public void enabledAnsiOutput() {
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}
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public static AnsiOutputControl get() {
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try {
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Class.forName("org.springframework.boot.ansi.AnsiOutput");
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return new AnsiPresentOutputControl();
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}
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catch (ClassNotFoundException ex) {
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return new AnsiOutputControl();
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}
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}
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}
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private static class AnsiPresentOutputControl extends AnsiOutputControl {
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@Override
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public void disableAnsiOutput() {
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AnsiOutput.setEnabled(AnsiOutput.Enabled.NEVER);
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}
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@Override
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public void enabledAnsiOutput() {
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AnsiOutput.setEnabled(AnsiOutput.Enabled.DETECT);
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}
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}
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}

‎spring-boot-project/spring-boot-test/src/test/java/org/springframework/boot/test/extension/OutputCaptureExtendWithTests.java‎

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/*
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* Copyright 2012-2018 the original author or authors.
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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 org.springframework.boot.test.extension;
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import org.junit.jupiter.api.Test;
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import org.junit.jupiter.api.extension.BeforeAllCallback;
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import org.junit.jupiter.api.extension.ExtendWith;
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import org.junit.jupiter.api.extension.ExtensionContext;
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import static org.assertj.core.api.Assertions.assertThat;
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/**
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* Tests for {@link OutputCapture} when used via {@link ExtendWith}.
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*
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* @author Madhura Bhave
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*/
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@ExtendWith(OutputCapture.class)
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@ExtendWith(OutputCaptureExtendWithTests.BeforeAllExtension.class)
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public class OutputCaptureExtendWithTests {
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@Test
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void captureShouldReturnOutputCapturedBeforeTestMethod(OutputCapture output) {
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assertThat(output).contains("Before all");
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assertThat(output).doesNotContain("Hello");
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}
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@Test
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void captureShouldReturnAllCapturedOutput(OutputCapture output) {
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System.out.println("Hello World");
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System.err.println("Error!!!");
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assertThat(output).contains("Before all");
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assertThat(output).contains("Hello World");
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assertThat(output).contains("Error!!!");
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}
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static class BeforeAllExtension implements BeforeAllCallback {
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@Override
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public void beforeAll(ExtensionContext context) {
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System.out.println("Before all");
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}
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}
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}

‎spring-boot-project/spring-boot-test/src/test/java/org/springframework/boot/test/extension/OutputCaptureRegisterExtensionTests.java‎

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/*
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* Copyright 2012-2018 the original author or authors.
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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 org.springframework.boot.test.extension;
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import org.junit.jupiter.api.Test;
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import org.junit.jupiter.api.extension.RegisterExtension;
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import static org.assertj.core.api.Assertions.assertThat;
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/**
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* Tests for {@link OutputCapture} when used via {@link RegisterExtension}.
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*
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* @author Madhura Bhave
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*/
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public class OutputCaptureRegisterExtensionTests {
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@RegisterExtension
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OutputCapture output = new OutputCapture();
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@Test
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void captureShouldReturnAllCapturedOutput() {
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System.out.println("Hello World");
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System.err.println("Error!!!");
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assertThat(this.output).contains("Hello World");
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assertThat(this.output).contains("Error!!!");
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}
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}

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