jdk-24/test/jdk/tools/launcher/MainClassCantBeLoadedTest.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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/**
 * @test
 * @bug 8174694 8181033
 * @summary improve error message shown when main class can't be loaded
 * @compile MainClassCantBeLoadedTest.java
 * @run main MainClassCantBeLoadedTest
 */

import java.io.*;
import java.util.*;

public class MainClassCantBeLoadedTest extends TestHelper {
    private MainClassCantBeLoadedTest(){}

    @Test
    void testLoadingClassWithMissingSuper() throws Exception {
        if (!isEnglishLocale()) {
            return;
        }

        File cwd = new File(".");
        File srcDir = new File(cwd, "src");
        if (srcDir.exists()) {
            recursiveDelete(srcDir);
        }
        srcDir.mkdirs();

        /* we want to generate two classes A and B, where B is the superclass of A
         * class A has a main method
         */
        ArrayList<String> scratchpad = new ArrayList<>();
        scratchpad.add("public class A extends B {");
        scratchpad.add("    public static void main(String... args) {}");
        scratchpad.add("}");
        createFile(new File(srcDir, "A.java"), scratchpad);

        scratchpad.clear();
        scratchpad.add("class B {}");
        createFile(new File(srcDir, "B.java"), scratchpad);

        // let's compile both
        TestResult trCompilation = doExec(javacCmd,
                "-d", "out",
                new File(srcDir, "A.java").toString(),
                new File(srcDir, "B.java").toString());
        if (!trCompilation.isOK()) {
            System.err.println(trCompilation);
            throw new RuntimeException("Error: compiling");
        }

        // and now B is removed
        File outDir = new File(cwd, "out");
        File bClass = new File(outDir, "B.class");
        bClass.delete();

        // if A is executed
        TestResult trExecution = doExec(javaCmd, "-cp", "out", "A");
        // then this error message should be generated
        trExecution.contains("Error: Could not find or load main class A");
        trExecution.contains("Caused by: java.lang.NoClassDefFoundError: B");
        if (!trExecution.testStatus)
            System.err.println(trExecution);
    }

    public static void main(String[] args) throws Exception {
        MainClassCantBeLoadedTest a = new MainClassCantBeLoadedTest();
        a.run(args);
        if (testExitValue > 0) {
            System.out.println("Total of " + testExitValue + " failed");
            throw new RuntimeException("Test failed");
        } else {
            System.out.println("Test passed");
        }
    }
}