Issue #3166: STDOUT and STDERR are reset after console test execution

Author: Oyster-zx

documentation/src/docs/asciidoc/release-notes/release-notes-5.12.0-RC2.adoc

@@ -26,7 +26,8 @@ repository on GitHub.
 [[release-notes-5.13.0-M1-junit-platform-new-features-and-improvements]]
 ==== New Features and Improvements
 
-* ❓
+* New optional CLI options `--redirect-stdout` and `--redirect-stderr` to redirect stdout
+and stderr outputs to a file.
 
 
 [[release-notes-5.13.0-M1-junit-jupiter]]

documentation/src/docs/asciidoc/release-notes/release-notes-5.13.0-M1.adoc

@@ -104,12 +104,16 @@ private TestExecutionSummary executeTests(PrintWriter out, Optional<Path> report
 		Launcher launcher = launcherSupplier.get();
 		SummaryGeneratingListener summaryListener = registerListeners(out, reportsDir, launcher);
 
-		redirectStdStreams(outputOptions.getStdoutPath(), outputOptions.getStderrPath());
-
-		LauncherDiscoveryRequestBuilder discoveryRequestBuilder = toDiscoveryRequestBuilder(discoveryOptions);
-		reportsDir.ifPresent(dir -> discoveryRequestBuilder.configurationParameter(OUTPUT_DIR_PROPERTY_NAME,
-			dir.toAbsolutePath().toString()));
-		launcher.execute(discoveryRequestBuilder.build());
+		PrintStream originalOut = System.out;
+		PrintStream originalErr = System.err;
+		try {
+			redirectStdStreams(outputOptions.getStdoutPath(), outputOptions.getStderrPath());
+			launchTests(launcher, reportsDir);
+		}
+		finally {
+			System.setOut(originalOut);
+			System.setErr(originalErr);
+		}
 
 		TestExecutionSummary summary = summaryListener.getSummary();
 		if (summary.getTotalFailureCount() > 0 || outputOptions.getDetails() != Details.NONE) {
@@ -119,6 +123,13 @@ private TestExecutionSummary executeTests(PrintWriter out, Optional<Path> report
 		return summary;
 	}
 
+	private void launchTests(Launcher launcher, Optional<Path> reportsDir) {
+		LauncherDiscoveryRequestBuilder discoveryRequestBuilder = toDiscoveryRequestBuilder(discoveryOptions);
+		reportsDir.ifPresent(dir -> discoveryRequestBuilder.configurationParameter(OUTPUT_DIR_PROPERTY_NAME,
+			dir.toAbsolutePath().toString()));
+		launcher.execute(discoveryRequestBuilder.build());
+	}
+
 	private Optional<ClassLoader> createCustomClassLoader() {
 		List<Path> additionalClasspathEntries = discoveryOptions.getExistingAdditionalClasspathEntries();
 		if (!additionalClasspathEntries.isEmpty()) {

junit-platform-console/src/main/java/org/junit/platform/console/tasks/ConsoleTestExecutor.java

@@ -10,10 +10,16 @@
 
 package org.junit.platform.console;
 
+import static java.nio.file.Files.deleteIfExists;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.jupiter.api.Assertions.assertAll;
 import static org.junit.jupiter.api.Assertions.assertArrayEquals;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
 
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
@@ -92,4 +98,35 @@ void executeScanModules(final String line) {
 		assertEquals(0, new ConsoleLauncherWrapper().execute(args1).getTestsFoundCount());
 	}
 
+	@ParameterizedTest
+	@ValueSource(strings = { "--redirect-stdout", "--redirect-stderr" })
+	void executeWithRedirectedStdStream(String redirectedStream) throws IOException {
+
+		Path outputFile = Path.of("foo.txt");
+		var line = String.format(
+			"execute -e junit-jupiter --select-method org.junit.platform.console.options.StdStreamTest#printTest "
+					+ "%s %s",
+			redirectedStream, outputFile);
+		var args = line.split(" ");
+		new ConsoleLauncherWrapper().execute(args);
+
+		assertTrue(Files.exists(outputFile), "File does not exist.");
+		assertEquals(Files.size(outputFile), 20, "Invalid file size.");
+		deleteIfExists(outputFile);
+	}
+
+	@Test
+	void executeWithRedirectedStdStreamsToSameFile() throws IOException {
+		Path outputFile = Path.of("foo.txt");
+		var line = String.format(
+			"execute -e junit-jupiter --select-method org.junit.platform.console.options.StdStreamTest#printTest "
+					+ "--redirect-stdout %s --redirect-stderr %s",
+			outputFile, outputFile);
+		var args = line.split(" ");
+		new ConsoleLauncherWrapper().execute(args);
+
+		assertTrue(Files.exists(outputFile), "File does not exist.");
+		assertEquals(Files.size(outputFile), 40, "Invalid file size.");
+		deleteIfExists(outputFile);
+	}
 }

platform-tests/src/test/java/org/junit/platform/console/ConsoleLauncherIntegrationTests.java

@@ -0,0 +1,22 @@
+/*
+ * Copyright 2015-2025 the original author or authors.
+ *
+ * All rights reserved. This program and the accompanying materials are
+ * made available under the terms of the Eclipse Public License v2.0 which
+ * accompanies this distribution and is available at
+ *
+ * https://www.eclipse.org/legal/epl-v20.html
+ */
+
+package org.junit.platform.console.options;
+
+import org.junit.jupiter.api.Test;
+
+public class StdStreamTest {
+
+	@Test
+	void printTest() {
+		System.out.print("Writing to STDOUT...");
+		System.err.print("Writing to STDERR...");
+	}
+}