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Testing Empty 9-Patch PNG File Handling in Apktool

This test suite validates the handling of empty 9-patch PNG files during APK decoding in the Apktool library. It ensures proper extraction and preservation of zero-byte 9-patch image files, which is a critical edge case in Android resource processing.

Test Coverage Overview

The test suite focuses on verifying the correct handling of empty 9-patch PNG files during APK decoding.

Key areas covered include:

Validation of empty 9-patch file extraction
Verification of file system operations
Preservation of zero-byte file characteristics
Resource directory structure integrity

Implementation Analysis

The implementation utilizes JUnit 4 framework with a structured setup-execute-verify pattern.

Technical implementation features:

ExtFile wrapper usage for APK handling
Resource directory copying via TestUtils
Inheritance from BaseTest for common functionality
Direct file system verification for test assertions

Technical Details

Testing infrastructure includes:

JUnit 4 testing framework
Custom ApkDecoder utility
TestUtils for resource management
ExtFile for enhanced file operations
Temporary directory management through BaseTest

Best Practices Demonstrated

The test exemplifies several testing best practices:

Clear test method naming convention
Proper test setup using @BeforeClass
Resource cleanup through inherited base class
Specific assertions for file existence and properties
Isolated test environment using temporary directories

ibotpeaches/apktool

brut.apktool/apktool-lib/src/test/java/brut/androlib/decode/Empty9PatchTest.java

            
/*
 *  Copyright (C) 2010 Ryszard Wiśniewski <[email protected]>
 *  Copyright (C) 2010 Connor Tumbleson <[email protected]>
 *
 *  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 brut.androlib.decode;

import brut.androlib.ApkDecoder;
import brut.androlib.BaseTest;
import brut.androlib.TestUtils;
import brut.common.BrutException;
import brut.directory.ExtFile;

import java.io.File;

import org.junit.*;
import static org.junit.Assert.*;

public class Empty9PatchTest extends BaseTest {
    private static final String TEST_APK = "empty9patch.apk";

    @BeforeClass
    public static void beforeClass() throws Exception {
        TestUtils.copyResourceDir(Empty9PatchTest.class, "decode/empty9patch", sTmpDir);
    }

    @Test
    public void decodeWithEmpty9PatchFile() throws BrutException {
        ExtFile testApk = new ExtFile(sTmpDir, TEST_APK);
        ExtFile testDir = new ExtFile(testApk + ".out");
        new ApkDecoder(testApk, sConfig).decode(testDir);

        File aPng = new File(testDir, "res/drawable-xhdpi/empty.9.png");
        assertTrue(aPng.isFile());
        assertEquals(0, aPng.length());
    }
}