src/test/java/org/apache/bcel/util/LruCacheClassPathRepositoryTest.java

/*
 * 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, 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.apache.bcel.util;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertNull;
import static org.junit.jupiter.api.Assertions.assertThrows;

import java.io.IOException;

import org.apache.bcel.classfile.JavaClass;
import org.junit.jupiter.api.Test;

/**
 * Tests {@link LruCacheClassPathRepository}.
 */
class LruCacheClassPathRepositoryTest {

    @Test
    void testCacheEviction() throws ClassNotFoundException, IOException {
        try (ClassPath classPath = new ClassPath("")) {
            final LruCacheClassPathRepository repository = new LruCacheClassPathRepository(classPath, 2);
            final JavaClass class1 = repository.loadClass("java.lang.String");
            assertNotNull(class1);
            final JavaClass class2 = repository.loadClass("java.lang.Long");
            assertNotNull(class2);
            final JavaClass class3 = repository.loadClass("java.lang.Integer"); // Evicts class1
            assertNotNull(class3);

            assertNull(repository.findClass("java.lang.String"));
            final JavaClass cachedClass2 = repository.findClass("java.lang.Long");
            assertEquals(class2, cachedClass2);
        }
    }

    @Test
    void testLeastRecentlyUsedEviction() throws ClassNotFoundException, IOException {
        try (ClassPath classPath = new ClassPath("")) {
            final LruCacheClassPathRepository repository = new LruCacheClassPathRepository(classPath, 2);
            final JavaClass class1 = repository.loadClass("java.lang.String");
            assertNotNull(class1);
            final JavaClass class2 = repository.loadClass("java.lang.Long");
            assertNotNull(class2);
            repository.findClass("java.lang.String"); // Uses class1
            final JavaClass class3 = repository.loadClass("java.lang.Integer"); // Evicts class2
            assertNotNull(class3);

            assertNull(repository.findClass("java.lang.Long"));
            final JavaClass cachedClass1 = repository.findClass("java.lang.String");
            assertEquals(class1, cachedClass1);
        }
    }

    @Test
    void testZeroCacheSize() throws IOException {
        try (ClassPath classPath = new ClassPath("")) {
            assertThrows(IllegalArgumentException.class, () -> new LruCacheClassPathRepository(classPath, 0));
        }
    }
}