Polish "Add module to support testing of generated code"

See gh-28120

Co-authored-by: Andy Wilkinson <wilkinsona@vmware.com>

spring-core-test/spring-core-test.gradle

@@ -1,5 +1,3 @@
-import com.github.jengelman.gradle.plugins.shadow.tasks.ShadowJar
-
 description = "Spring Core Test"
 
 dependencies {

spring-core-test/src/main/java/org/springframework/aot/test/generator/compile/Compiled.java

@@ -25,6 +25,7 @@ import org.springframework.aot.test.generator.file.ResourceFile;
 import org.springframework.aot.test.generator.file.ResourceFiles;
 import org.springframework.aot.test.generator.file.SourceFile;
 import org.springframework.aot.test.generator.file.SourceFiles;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -42,6 +43,7 @@ public class Compiled {
 
 	private final ResourceFiles resourceFiles;
 
+	@Nullable
 	private List<Class<?>> compiledClasses;
 
 
@@ -107,8 +109,7 @@ public class Compiled {
 	 * @throws IllegalStateException if no instance can be found or instantiated
 	 */
 	public <T> T getInstance(Class<T> type) {
-		List<Class<?>> matching = getAllCompiledClasses().stream().filter(
-				candidate -> type.isAssignableFrom(candidate)).toList();
+		List<Class<?>> matching = getAllCompiledClasses().stream().filter(type::isAssignableFrom).toList();
 		Assert.state(!matching.isEmpty(), () -> "No instance found of type " + type.getName());
 		Assert.state(matching.size() == 1, () -> "Multiple instances found of type " + type.getName());
 		return newInstance(matching.get(0));

spring-core-test/src/main/java/org/springframework/aot/test/generator/compile/DynamicClassFileObject.java

@@ -17,7 +17,6 @@
 package org.springframework.aot.test.generator.compile;
 
 import java.io.ByteArrayOutputStream;
-import java.io.IOException;
 import java.io.OutputStream;
 import java.net.URI;
 
@@ -32,7 +31,7 @@ import javax.tools.SimpleJavaFileObject;
  */
 class DynamicClassFileObject extends SimpleJavaFileObject {
 
-	private volatile byte[] bytes;
+	private volatile byte[] bytes = new byte[0];
 
 
 	DynamicClassFileObject(String className) {
@@ -42,7 +41,7 @@ class DynamicClassFileObject extends SimpleJavaFileObject {
 
 
 	@Override
-	public OutputStream openOutputStream() throws IOException {
+	public OutputStream openOutputStream() {
 		return new JavaClassOutputStream();
 	}
 
@@ -54,7 +53,7 @@ class DynamicClassFileObject extends SimpleJavaFileObject {
 	class JavaClassOutputStream extends ByteArrayOutputStream {
 
 		@Override
-		public void close() throws IOException {
+		public void close() {
 			DynamicClassFileObject.this.bytes = toByteArray();
 		}
 

spring-core-test/src/main/java/org/springframework/aot/test/generator/compile/DynamicClassLoader.java

@@ -23,6 +23,7 @@ import java.lang.System.Logger;
 import java.lang.System.Logger.Level;
 import java.lang.invoke.MethodHandles;
 import java.lang.invoke.MethodHandles.Lookup;
+import java.lang.reflect.Modifier;
 import java.net.MalformedURLException;
 import java.net.URL;
 import java.net.URLConnection;
@@ -35,17 +36,18 @@ import org.springframework.aot.test.generator.file.ResourceFile;
 import org.springframework.aot.test.generator.file.ResourceFiles;
 import org.springframework.aot.test.generator.file.SourceFile;
 import org.springframework.aot.test.generator.file.SourceFiles;
+import org.springframework.lang.Nullable;
 
 /**
  * {@link ClassLoader} used to expose dynamically generated content.
  *
  * @author Phillip Webb
+ * @author Andy Wilkinson
  * @since 6.0
  */
 public class DynamicClassLoader extends ClassLoader {
 
-	private static final Logger logger = System.getLogger(
-			DynamicClassLoader.class.getName());
+	private static final Logger logger = System.getLogger(DynamicClassLoader.class.getName());
 
 
 	private final SourceFiles sourceFiles;
@@ -54,10 +56,13 @@ public class DynamicClassLoader extends ClassLoader {
 
 	private final Map<String, DynamicClassFileObject> classFiles;
 
+	private final ClassLoader sourceLoader;
 
-	public DynamicClassLoader(ClassLoader parent, SourceFiles sourceFiles,
+
+	public DynamicClassLoader(ClassLoader sourceLoader, SourceFiles sourceFiles,
 			ResourceFiles resourceFiles, Map<String, DynamicClassFileObject> classFiles) {
-		super(parent);
+		super(sourceLoader.getParent());
+		this.sourceLoader = sourceLoader;
 		this.sourceFiles = sourceFiles;
 		this.resourceFiles = resourceFiles;
 		this.classFiles = classFiles;
@@ -70,7 +75,22 @@ public class DynamicClassLoader extends ClassLoader {
 		if (classFile != null) {
 			return defineClass(name, classFile);
 		}
-		return super.findClass(name);
+		try {
+			Class<?> fromSourceLoader = this.sourceLoader.loadClass(name);
+			if (Modifier.isPublic(fromSourceLoader.getModifiers())) {
+				return fromSourceLoader;
+			}
+		}
+		catch (Exception ex) {
+			// Continue
+		}
+		try (InputStream classStream = this.sourceLoader.getResourceAsStream(name.replace(".", "/") + ".class")) {
+			byte[] bytes = classStream.readAllBytes();
+			return defineClass(name, bytes, 0, bytes.length, null);
+		}
+		catch (IOException ex) {
+			throw new ClassNotFoundException(name);
+		}
 	}
 
 	private Class<?> defineClass(String name, DynamicClassFileObject classFile) {
@@ -101,6 +121,7 @@ public class DynamicClassLoader extends ClassLoader {
 	}
 
 	@Override
+	@Nullable
 	protected URL findResource(String name) {
 		ResourceFile file = this.resourceFiles.get(name);
 		if (file != null) {
@@ -118,10 +139,11 @@ public class DynamicClassLoader extends ClassLoader {
 
 	private static class SingletonEnumeration<E> implements Enumeration<E> {
 
+		@Nullable
 		private E element;
 
 
-		SingletonEnumeration(E element) {
+		SingletonEnumeration(@Nullable E element) {
 			this.element = element;
 		}
 
@@ -132,6 +154,7 @@ public class DynamicClassLoader extends ClassLoader {
 		}
 
 		@Override
+		@Nullable
 		public E nextElement() {
 			E next = this.element;
 			this.element = null;

spring-core-test/src/main/java/org/springframework/aot/test/generator/compile/DynamicJavaFileManager.java

@@ -42,7 +42,6 @@ class DynamicJavaFileManager extends ForwardingJavaFileManager<JavaFileManager>
 			new LinkedHashMap<>());
 
 
-
 	DynamicJavaFileManager(JavaFileManager fileManager, ClassLoader classLoader) {
 		super(fileManager);
 		this.classLoader = classLoader;

spring-core-test/src/main/java/org/springframework/aot/test/generator/compile/DynamicJavaFileObject.java

@@ -16,7 +16,6 @@
 
 package org.springframework.aot.test.generator.compile;
 
-import java.io.IOException;
 import java.net.URI;
 
 import javax.tools.JavaFileObject;
@@ -43,7 +42,7 @@ class DynamicJavaFileObject extends SimpleJavaFileObject {
 
 
 	@Override
-	public CharSequence getCharContent(boolean ignoreEncodingErrors) throws IOException {
+	public CharSequence getCharContent(boolean ignoreEncodingErrors) {
 		return this.sourceFile.getContent();
 	}
 

spring-core-test/src/main/java/org/springframework/aot/test/generator/compile/TestCompiler.java

@@ -33,6 +33,7 @@ import org.springframework.aot.test.generator.file.ResourceFiles;
 import org.springframework.aot.test.generator.file.SourceFile;
 import org.springframework.aot.test.generator.file.SourceFiles;
 import org.springframework.aot.test.generator.file.WritableContent;
+import org.springframework.lang.Nullable;
 
 /**
  * Utility that can be used to dynamically compile and test Java source code.
@@ -43,6 +44,7 @@ import org.springframework.aot.test.generator.file.WritableContent;
  */
 public final class TestCompiler {
 
+	@Nullable
 	private final ClassLoader classLoader;
 
 	private final JavaCompiler compiler;
@@ -52,7 +54,7 @@ public final class TestCompiler {
 	private final ResourceFiles resourceFiles;
 
 
-	private TestCompiler(ClassLoader classLoader, JavaCompiler compiler,
+	private TestCompiler(@Nullable ClassLoader classLoader, JavaCompiler compiler,
 			SourceFiles sourceFiles, ResourceFiles resourceFiles) {
 		this.classLoader = classLoader;
 		this.compiler = compiler;
@@ -186,14 +188,14 @@ public final class TestCompiler {
 	}
 
 	private DynamicClassLoader compile() {
-		ClassLoader classLoader = (this.classLoader != null) ? this.classLoader
+		ClassLoader classLoaderToUse = (this.classLoader != null) ? this.classLoader
 				: Thread.currentThread().getContextClassLoader();
 		List<DynamicJavaFileObject> compilationUnits = this.sourceFiles.stream().map(
 				DynamicJavaFileObject::new).toList();
 		StandardJavaFileManager standardFileManager = this.compiler.getStandardFileManager(
 				null, null, null);
 		DynamicJavaFileManager fileManager = new DynamicJavaFileManager(
-				standardFileManager, classLoader);
+				standardFileManager, classLoaderToUse);
 		if (!this.sourceFiles.isEmpty()) {
 			Errors errors = new Errors();
 			CompilationTask task = this.compiler.getTask(null, fileManager, errors, null,
@@ -203,7 +205,7 @@ public final class TestCompiler {
 				throw new CompilationException("Unable to compile source" + errors);
 			}
 		}
-		return new DynamicClassLoader(this.classLoader, this.sourceFiles,
+		return new DynamicClassLoader(classLoaderToUse, this.sourceFiles,
 				this.resourceFiles, fileManager.getClassFiles());
 	}
 
@@ -223,8 +225,8 @@ public final class TestCompiler {
 				this.message.append(" ");
 				this.message.append(diagnostic.getSource().getName());
 				this.message.append(" ");
-				this.message.append(
-						diagnostic.getLineNumber() + ":" + diagnostic.getColumnNumber());
+				this.message.append(diagnostic.getLineNumber()).append(":")
+						.append(diagnostic.getColumnNumber());
 			}
 		}
 

spring-core-test/src/main/java/org/springframework/aot/test/generator/compile/package-info.java

@@ -0,0 +1,9 @@
+/**
+ * Support classes for compiling and testing generated code.
+ */
+@NonNullApi
+@NonNullFields
+package org.springframework.aot.test.generator.compile;
+
+import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;

spring-core-test/src/main/java/org/springframework/aot/test/generator/file/DynamicFile.java

@@ -19,7 +19,7 @@ package org.springframework.aot.test.generator.file;
 import java.io.IOException;
 import java.util.Objects;
 
-import org.assertj.core.util.Strings;
+import org.springframework.util.Assert;
 
 /**
  * Abstract base class for dynamically generated files.
@@ -29,7 +29,7 @@ import org.assertj.core.util.Strings;
  * @see SourceFile
  * @see ResourceFile
  */
-public abstract sealed class DynamicFile permits SourceFile,ResourceFile {
+public abstract sealed class DynamicFile permits SourceFile, ResourceFile {
 
 
 	private final String path;
@@ -38,21 +38,14 @@ public abstract sealed class DynamicFile permits SourceFile,ResourceFile {
 
 
 	protected DynamicFile(String path, String content) {
-		if (Strings.isNullOrEmpty(content)) {
-			throw new IllegalArgumentException("'path' must not to be empty");
-		}
-		if (Strings.isNullOrEmpty(content)) {
-			throw new IllegalArgumentException("'content' must not to be empty");
-		}
+		Assert.hasText(path, "Path must not be empty");
+		Assert.hasText(content, "Content must not be empty");
 		this.path = path;
 		this.content = content;
 	}
 
 
 	protected static String toString(WritableContent writableContent) {
-		if (writableContent == null) {
-			throw new IllegalArgumentException("'writableContent' must not to be empty");
-		}
 		try {
 			StringBuilder stringBuilder = new StringBuilder();
 			writableContent.writeTo(stringBuilder);

spring-core-test/src/main/java/org/springframework/aot/test/generator/file/DynamicFileAssert.java

@@ -18,6 +18,8 @@ package org.springframework.aot.test.generator.file;
 
 import org.assertj.core.api.AbstractAssert;
 
+import org.springframework.lang.Nullable;
+
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
@@ -42,7 +44,7 @@ public class DynamicFileAssert<A extends DynamicFileAssert<A, F>, F extends Dyna
 		return this.myself;
 	}
 
-	public A isEqualTo(Object expected) {
+	public A isEqualTo(@Nullable Object expected) {
 		if (expected instanceof DynamicFile) {
 			return super.isEqualTo(expected);
 		}

spring-core-test/src/main/java/org/springframework/aot/test/generator/file/SourceFileAssert.java

@@ -27,6 +27,8 @@ import com.thoughtworks.qdox.model.JavaType;
 import org.assertj.core.error.BasicErrorMessageFactory;
 import org.assertj.core.internal.Failures;
 
+import org.springframework.lang.Nullable;
+
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
@@ -43,11 +45,11 @@ public class SourceFileAssert extends DynamicFileAssert<SourceFileAssert, Source
 	}
 
 
-	public SourceFileAssert implementsInterface(Class<?> type) {
-		return implementsInterface((type != null) ? type.getName() : (String) null);
+	public SourceFileAssert implementsInterface(@Nullable Class<?> type) {
+		return implementsInterface((type != null ? type.getName() : null));
 	}
 
-	public SourceFileAssert implementsInterface(String name) {
+	public SourceFileAssert implementsInterface(@Nullable String name) {
 		JavaClass javaClass = getJavaClass();
 		assertThat(javaClass.getImplements()).as("implements").map(
 				JavaType::getFullyQualifiedName).contains(name);

spring-core-test/src/main/java/org/springframework/aot/test/generator/file/package-info.java

@@ -0,0 +1,11 @@
+/**
+ * Support classes for running assertions on generated files.
+ *
+ * @author Stephane Nicoll
+ */
+@NonNullApi
+@NonNullFields
+package org.springframework.aot.test.generator.file;
+
+import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;

spring-core-test/src/test/java/com/example/PackagePrivate.java

@@ -0,0 +1,26 @@
+/*
+ * 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 com.example;
+
+
+class PackagePrivate {
+
+	String perform() {
+		return "Hello from PackagePrivate";
+	}
+
+}

spring-core-test/src/test/java/com/example/PublicInterface.java

@@ -0,0 +1,23 @@
+/*
+ * 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 com.example;
+
+public interface PublicInterface {
+
+	String perform();
+
+}

spring-core-test/src/test/java/org/springframework/aot/test/generator/compile/TestCompilerTests.java

@@ -18,6 +18,7 @@ package org.springframework.aot.test.generator.compile;
 
 import java.util.function.Supplier;
 
+import com.example.PublicInterface;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.aot.test.generator.file.ResourceFile;
@@ -33,6 +34,7 @@ import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
  * Tests for {@link TestCompiler}.
  *
  * @author Phillip Webb
+ * @author Andy Wilkinson
  */
 class TestCompilerTests {
 
@@ -106,7 +108,7 @@ class TestCompilerTests {
 		assertThatExceptionOfType(CompilationException.class).isThrownBy(
 				() -> TestCompiler.forSystem().withSources(
 						SourceFile.of(HELLO_BAD)).compile(compiled -> {
-						}));
+				}));
 	}
 
 	@Test
@@ -167,6 +169,24 @@ class TestCompilerTests {
 		});
 	}
 
+	@Test
+	void compiledCodeCanAccessExistingPackagePrivateClass() {
+		SourceFiles sourceFiles = SourceFiles.of(SourceFile.of("""
+				package com.example;
+
+				public class Test implements PublicInterface {
+
+					public String perform() {
+						return new PackagePrivate().perform();
+					}
+
+				}
+				"""));
+		TestCompiler.forSystem().compile(sourceFiles, compiled -> assertThat(
+				compiled.getInstance(PublicInterface.class, "com.example.Test").perform())
+				.isEqualTo("Hello from PackagePrivate"));
+	}
+
 	private void assertSuppliesHelloWorld(Compiled compiled) {
 		assertThat(compiled.getInstance(Supplier.class).get()).isEqualTo("Hello World!");
 	}

spring-core-test/src/test/java/org/springframework/aot/test/generator/file/SourceFileTests.java

@@ -22,7 +22,6 @@ import com.thoughtworks.qdox.model.JavaSource;
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
 
 /**
@@ -42,13 +41,6 @@ class SourceFileTests {
 			}
 			""";
 
-	@Test
-	void ofWhenContentIsNullThrowsException() {
-		assertThatIllegalArgumentException().isThrownBy(
-				() -> SourceFile.of((WritableContent) null)).withMessage(
-						"'writableContent' must not to be empty");
-	}
-
 	@Test
 	void ofWhenContentIsEmptyThrowsException() {
 		assertThatIllegalStateException().isThrownBy(() -> SourceFile.of("")).withMessage(