java - クラス拡張機能に対して InstantiationException がスローされる

Question

次のクラスを作成しました。クラス内の残りのコードは @Overrides です。コードの残りの部分がここに関連しているかどうかをお知らせください。追加します。

public class ListCmd extends LibraryCommand {

    public ListCmd(String argumentInput) {
        super(CommandType.LIST, argumentInput);
    }

...

私のテストが実行されると、InstantiationException がスローされます。

API を見て、このエラーをスローする原因を調べて絞り込もうとしましたが、役に立ちませんでした。エラーの 1 つのログを次に示します。

java.lang.InstantiationException
    at java.base/jdk.internal.reflect.InstantiationExceptionConstructorAccessorImpl.newInstance(InstantiationExceptionConstructorAccessorImpl.java:48)
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490)
    at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java:217)
    at org.junit.runners.BlockJUnit4ClassRunner$1.runReflectiveCall(BlockJUnit4ClassRunner.java:266)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.BlockJUnit4ClassRunner.methodBlock(BlockJUnit4ClassRunner.java:263)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
    at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230)
    at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)

このテストを実行しています

import org.junit.Before;

import java.util.ArrayList;
import java.util.List;

public abstract class ListCmdTest extends CommandTest {

    protected static final String SHORT_ARGUMENT = "short";
    protected static final String LONG_ARGUMENT = "long";

    @Override
    protected CommandType getCmdType() {
        return CommandType.LIST;
    }

    @Before
    public void setup() {
        testCommand = new ListCmd(SHORT_ARGUMENT);

        testLibrary = new LibraryData();
        List<BookEntry> bookData = new ArrayList<>();
        bookData.add(new BookEntry("TitleA", new String[]{"AuthorA"}, 3.2f, "ISBNA", 500));
        bookData.add(new BookEntry("TitleB", new String[]{"AuthorB"}, 4.3f, "ISBNB", 400));
        bookData.add(new BookEntry("TitleC", new String[]{"AuthorC"}, 1.3f, "ISBNC", 300));
        FieldTestUtils.setPrivateField(testLibrary, testLibrary.getClass(), "books", bookData);
    }
}

そして、これらのテストは失敗します

import org.junit.Test;

import static org.junit.Assert.assertEquals;

public abstract class CommandTest {

    protected static final String TITLE_ARGUMENT = "TITLE";
    protected static final String AUTHOR_ARGUMENT = "AUTHOR";

    protected static final String BLANK_ARGUMENT = "";

    protected LibraryCommand testCommand;
    protected LibraryData testLibrary;

    public CommandTest() {
        testCommand = null;
        testLibrary = null;
    }

    protected abstract CommandType getCmdType();

    // ------------------------- initialisation tests --------------------

    @Test
    public void testClassCommandExtension() {
        assertEquals(testCommand.getClass() + " has unexpected superclass.", LibraryCommand.class,
                testCommand.getClass().getSuperclass());
    }

    @Test
    public void testCtorSuperclassCall() {
        CommandTestUtils.checkCtorSuperclassCall(testCommand, getCmdType());
    }

    // ------------------------- parseArguments tests --------------------

    @Test
    public void testIsParseArgumentsOverridden() {
        CommandTestUtils.checkIfParseArgumentsIsOverridden(testCommand);
    }

    // ------------------------- execute tests --------------------

    @Test(expected = NullPointerException.class)
    public void testExecuteLibraryDataNull() {
        testCommand.execute(null);
    }

``