Introduce CLI for triggering AOT test context processing

This commit introduces TestAotProcessor which replaces
ProcessTestsAheadOfTimeCommand, removes the dependency on picocli, and
aligns with the implementation of the AotProcessor in Spring Boot.

TestAotProcessor is a command-line application (CLI) that scans the
provided classpath roots for Spring integration test classes and then
generates AOT artifacts for those test classes in the provided output
directories.

This CLI is only intended to be used by build tools.

Closes gh-28825

Author: sbrannen

spring-test/src/main/java/org/springframework/test/context/aot/ProcessTestsAheadOfTimeCommand.java

@@ -0,0 +1,156 @@
+/*
+ * Copyright 2002-2022 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.test.context.aot;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Arrays;
+import java.util.Set;
+import java.util.stream.Stream;
+
+import org.springframework.aot.generate.FileSystemGeneratedFiles;
+import org.springframework.aot.generate.GeneratedFiles;
+import org.springframework.aot.generate.GeneratedFiles.Kind;
+import org.springframework.aot.hint.RuntimeHints;
+import org.springframework.aot.nativex.FileNativeConfigurationWriter;
+import org.springframework.util.Assert;
+import org.springframework.util.FileSystemUtils;
+
+/**
+ * Command-line application that scans the provided classpath roots for Spring
+ * integration test classes and then generates AOT artifacts for those test
+ * classes in the provided output directories.
+ *
+ * <p><strong>For internal use only.</strong>
+ *
+ * @author Sam Brannen
+ * @author Stephane Nicoll
+ * @author Andy Wilkinson
+ * @author Phillip Webb
+ * @since 6.0
+ * @see TestClassScanner
+ * @see TestContextAotGenerator
+ * @see FileNativeConfigurationWriter
+ * @see org.springframework.boot.AotProcessor
+ */
+public class TestAotProcessor {
+
+	private final Path[] classpathRoots;
+
+	private final Path sourceOutput;
+
+	private final Path resourceOutput;
+
+	private final Path classOutput;
+
+	private final String groupId;
+
+	private final String artifactId;
+
+
+	/**
+	 * Create a new processor for the specified test classpath roots and
+	 * general settings.
+	 *
+	 * @param classpathRoots the classpath roots to scan for test classes
+	 * @param sourceOutput the location of generated sources
+	 * @param resourceOutput the location of generated resources
+	 * @param classOutput the location of generated classes
+	 * @param groupId the group ID of the application, used to locate
+	 * {@code native-image.properties}
+	 * @param artifactId the artifact ID of the application, used to locate
+	 * {@code native-image.properties}
+	 */
+	public TestAotProcessor(Path[] classpathRoots, Path sourceOutput, Path resourceOutput, Path classOutput,
+			String groupId, String artifactId) {
+
+		this.classpathRoots = classpathRoots;
+		this.sourceOutput = sourceOutput;
+		this.resourceOutput = resourceOutput;
+		this.classOutput = classOutput;
+		this.groupId = groupId;
+		this.artifactId = artifactId;
+	}
+
+
+	/**
+	 * Trigger processing of the test classes in the configured classpath roots.
+	 */
+	public void process() {
+		deleteExistingOutput();
+		performAotProcessing();
+	}
+
+	private void deleteExistingOutput() {
+		deleteExistingOutput(this.sourceOutput, this.resourceOutput, this.classOutput);
+	}
+
+	private void deleteExistingOutput(Path... paths) {
+		for (Path path : paths) {
+			try {
+				FileSystemUtils.deleteRecursively(path);
+			}
+			catch (IOException ex) {
+				throw new UncheckedIOException("Failed to delete existing output in '%s'".formatted(path), ex);
+			}
+		}
+	}
+
+	private void performAotProcessing() {
+		TestClassScanner scanner = new TestClassScanner(Set.of(this.classpathRoots));
+		Stream<Class<?>> testClasses = scanner.scan();
+
+		GeneratedFiles generatedFiles = new FileSystemGeneratedFiles(this::getRoot);
+		TestContextAotGenerator generator = new TestContextAotGenerator(generatedFiles);
+		generator.processAheadOfTime(testClasses);
+
+		writeHints(generator.getRuntimeHints());
+	}
+
+	private Path getRoot(Kind kind) {
+		return switch (kind) {
+			case SOURCE -> this.sourceOutput;
+			case RESOURCE -> this.resourceOutput;
+			case CLASS -> this.classOutput;
+		};
+	}
+
+	private void writeHints(RuntimeHints hints) {
+		FileNativeConfigurationWriter writer =
+				new FileNativeConfigurationWriter(this.resourceOutput, this.groupId, this.artifactId);
+		writer.write(hints);
+	}
+
+
+	public static void main(String[] args) {
+		int requiredArgs = 6;
+		Assert.isTrue(args.length >= requiredArgs, () ->
+				"Usage: %s <classpathRoots> <sourceOutput> <resourceOutput> <classOutput> <groupId> <artifactId>"
+					.formatted(TestAotProcessor.class.getName()));
+		Path[] classpathRoots = Arrays.stream(args[0].split(File.pathSeparator)).map(Paths::get).toArray(Path[]::new);
+		Path sourceOutput = Paths.get(args[1]);
+		Path resourceOutput = Paths.get(args[2]);
+		Path classOutput = Paths.get(args[3]);
+		String groupId = args[4];
+		String artifactId = args[5];
+		new TestAotProcessor(classpathRoots, sourceOutput, resourceOutput, classOutput, groupId, artifactId).process();
+	}
+
+}

spring-test/src/main/java/org/springframework/test/context/aot/TestAotProcessor.java

@@ -88,4 +88,13 @@ Path classpathRoot() {
 		}
 	}
 
+	Path classpathRoot(Class<?> clazz) {
+		try {
+			return Paths.get(clazz.getProtectionDomain().getCodeSource().getLocation().toURI());
+		}
+		catch (Exception ex) {
+			throw new RuntimeException(ex);
+		}
+	}
+
 }