ClassUtilsGetShortClassNameTest.java
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* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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,
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* See the License for the specific language governing permissions and
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package org.apache.commons.lang3;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.junit.jupiter.api.Assumptions.assumeTrue;
import java.io.IOException;
import java.net.URL;
import java.net.URLClassLoader;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Map;
import javax.tools.JavaCompiler;
import javax.tools.ToolProvider;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.io.TempDir;
/**
* {@link ClassUtils#getShortClassName(Class)} can throw {@link NoClassDefFoundError} when the supplied class is an inner class whose enclosing (outer) class
* has been removed from the classpath.
*
* <p>
* The code path lives in the {@code while (x != null)} loop of {@code getShortClassName(Class)}: it calls {@code x.getSimpleName()} and
* {@code x.getDeclaringClass()}. Both of those JDK methods resolve the {@code InnerClasses} attribute of the inner class' bytecode, and when the enclosing
* class is missing the JVM throws {@link NoClassDefFoundError} from inside {@code Class#getDeclaringClass0}/{@code getSimpleBinaryName}.
* </p>
* <p>
* The test compiles two classes ({@code F030Outer} and {@code F030Outer$Inner}) with the in-process {@code javax.tools.JavaCompiler}, deletes the outer class
* file, loads the inner class via a fresh {@link URLClassLoader}, and then invokes {@link ClassUtils#getShortClassName(Class)}.
* </p>
*
* <p>
* At baseline (commit {@code 8538458e7}) the call propagates {@link NoClassDefFoundError}. After the fix the {@code if/else} block around
* {@code isAnonymousClass}/{@code isLocalClass} is wrapped in a {@code try / catch (NoClassDefFoundError)} that falls back to
* {@link ClassUtils#getShortClassName(String)} on the binary name.
* </p>
*/
public class ClassUtilsGetShortClassNameTest {
// @formatter:off
private static final String OUTER_SRC = ""
+ "package f030;\n"
+ "public class F030Outer {\n"
+ " public static class Inner {\n"
+ " public int value;\n"
+ " }\n"
+ "}\n";
// @formatter:on
/**
* Compiles {@code f030.F030Outer} (and its nested {@code Inner}) into the supplied directory using the in-process Java compiler.
*
* @return {@code true} on success, {@code false} if the compiler is not available (running on a JRE rather than a JDK).
*/
private static boolean compileOuterWithInner(final Path classesDir) throws IOException {
final JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
assertNotNull("JDK compiler missing");
final Path srcDir = classesDir.resolve("..").resolve("src").normalize();
Files.createDirectories(srcDir);
final Path outerJava = srcDir.resolve("F030Outer.java");
Files.write(outerJava, OUTER_SRC.getBytes(StandardCharsets.UTF_8));
Files.createDirectories(classesDir);
return compiler.run(null, null, null, "-d", classesDir.toString(), outerJava.toString()) == 0;
}
/**
* Creates a child {@link URLClassLoader} that can resolve only the inner class file, the outer class file is deliberately omitted from the directory it
* points at, simulating a torn deployment / shaded JAR.
*/
private static URLClassLoader innerOnlyLoader(final Path innerOnlyDir) throws IOException {
final URL url = innerOnlyDir.toUri().toURL();
return new URLClassLoader(new URL[] { url }, ClassLoader.getSystemClassLoader().getParent());
}
/**
* Anonymous and local classes follow a separate code path that calls {@code getShortClassName(c.getName())} directly. The compiler-generated ordinal (fpr
* example, {@code $1}) is preserved by the legacy contract, so the short name ends with {@code ".<digits>"}.
*/
@Test
public void testAnonymousAndLocalClassesUseSeparatePath() {
final Runnable anon = new Runnable() {
@Override
public void run() {
/* no-op */
}
};
final String shortName = ClassUtils.getShortClassName(anon.getClass());
assertNotNull(shortName);
assertTrue(shortName.matches(".*\\.[0-9].*"), "Anonymous class short name should preserve the compiler ordinal: " + shortName);
}
@Test
public void testGetShortClassNameDoesNotThrowOnNormalClasses() {
assertEquals("String", ClassUtils.getShortClassName(String.class));
assertEquals("Map.Entry", ClassUtils.getShortClassName(Map.Entry.class));
assertEquals("int[]", ClassUtils.getShortClassName(int[].class));
}
@Test
public void testGetShortClassNameOnInnerClassWithMissingOuter(@TempDir final Path tempDir) throws Exception {
final Path classesDir = tempDir.resolve("classes");
assumeTrue(compileOuterWithInner(classesDir));
final Path outerClass = classesDir.resolve("f030").resolve("F030Outer.class");
final Path innerClass = classesDir.resolve("f030").resolve("F030Outer$Inner.class");
assumeTrue(Files.exists(outerClass) && Files.exists(innerClass), "Expected compiled class files to exist");
final Path innerOnly = tempDir.resolve("inner-only");
Files.createDirectories(innerOnly.resolve("f030"));
Files.copy(innerClass, innerOnly.resolve("f030").resolve("F030Outer$Inner.class"));
try (URLClassLoader cl = innerOnlyLoader(innerOnly)) {
final Class<?> inner = Class.forName("f030.F030Outer$Inner", false, cl);
assertEquals("f030.F030Outer$Inner", inner.getName());
// Sanity: at the JDK layer, both getSimpleName and getDeclaringClass
// throw NoClassDefFoundError for this inner class on the current JVM.
assertThrows(NoClassDefFoundError.class, inner::getSimpleName);
assertThrows(NoClassDefFoundError.class, inner::getDeclaringClass);
// Post-fix: ClassUtils.getShortClassName(Class) catches NoClassDefFoundError
// thrown anywhere inside the if (isAnonymous || isLocal){...} else {...} block
// and falls back to string-parsing the binary name "f030.F030Outer$Inner"
// which yields "F030Outer.Inner" (per the documented contract of
// getShortClassName(String): the '$' separator is replaced with '.').
assertEquals("F030Outer.Inner", ClassUtils.getShortClassName(inner));
}
}
@Test
public void testGetShortClassNameReturnsNonNullForStandardClasses() {
assertNotNull(ClassUtils.getShortClassName(String.class));
assertNotNull(ClassUtils.getShortClassName(Integer.class));
}
}