java - 深入 JUnit 参数化测试运行程序 : java. lang.ClassCastException : [Ljava. lang.Object；无法转换为 java.util.List

Question

我正在尝试使用 JUnit 的 ParameterizedTestRunner 构建我的第一个参数化测试。我在 JUnit 的深处遇到了一个奇怪的 ClassCastException，我无法弄清楚。

奇怪的是:Intellij 中的回溯似乎从未触及我的代码。

我的基类叫做 MultiLocaleParserTest，我的子类是 ExpectNoAltTagsInSellerNamesTest。亚马逊抓取，高兴!

/**
 * This is the base class for "multi-locale" tests.  Its children are intended
 * to be used with the JUnit Parameterized Test Runner.
 *
 * Currently, contains only boilerplate of use to child classes.
 *
 * @see <a href="https://github.com/junit-team/junit/wiki/Parameterized-tests">JUnit Parameterized Test Runner docs</a>
 */
public abstract class MultiLocaleParserTest extends BaseParserTest {

    private static ArrayList<ArrayList> fixtureList;
    private static ArrayList<ArrayList> expectedList;

    /**
     * Builds and returns an array that looks like this:
     *
     *  { { String amazonLocale, ArrayList fixtureData, ArrayList expectedData },
     *    { ... },
     *  }
     *
     * TODO: A possible (probable) refactor involves switching the "fixture" and
     *      "expected" data structures to Maps of some type, because it's more reader-
     *      friendly to see e.g. fixture.get("seller_name") than fixture.get(2).
     *
     * @param fixtureList An ArrayList of fixture data for the test the programmer is setting up.
     * @param expectedList An ArrayList of expected results for the test the programmer is setting up.
     * @return A data structure for use with parameterized tests as in class ExpectNoAltTagsInSellerNames.
     */
    protected static Object[] buildLocaleTestDataArray(ArrayList<ArrayList> fixtureList,
                                                       ArrayList<ArrayList> expectedList) throws Exception {
        MultiLocaleParserTest.fixtureList = fixtureList;
        MultiLocaleParserTest.expectedList = expectedList;
        if (fixtureList.size() != expectedList.size()) {
            throw new Exception("Need as many 'expected' entries as 'fixture' entries.");
        }

        int c = 0;
        ArrayList<Object[]> testParamData = new ArrayList<>();
        Iterator fixtureIterator = fixtureList.iterator();
        Iterator expectedIterator = expectedList.iterator();
        while (fixtureIterator.hasNext()) {
            ArrayList myFixtureList = (ArrayList)fixtureIterator.next();
            ArrayList myExpectedList = (ArrayList)expectedIterator.next();

            String fLocale = (String)myFixtureList.remove(0);
            String eLocale = (String)myExpectedList.remove(0);

            if (!fLocale.equals(eLocale)) {
                throw new Exception("List params to this method must be in the same order.");
            }

            ArrayList<Object> testParamList = new ArrayList<>();
            testParamList.add(fLocale);
            testParamList.add(myFixtureList);
            testParamList.add(myExpectedList);

            testParamData.add(testParamList.toArray());
            c++;
        }

        return testParamData.toArray();
    }

    public void smokeTest() throws Exception {
        // @todo derp
    }
}

还有子类，它试图实际使用基类。很抱歉，这是我 6 年没有接触过 Java 并拥有 Python 思维方式和我们现有代码库的混合体。

/**
 * Regression test vs MT-786 (alt="foo visible in MPS seller name fields)
 *
 * This multi-locale test checks that the string "alt=" does not appear in any
 * seller names which are images, rather than text.
 *
 * This is the proof-of-concept use of JUnit Parameterized tests for multiple
 * Amazon locales.
 *
 * @see MultiLocaleParserTest
 * @see <a href="https://github.com/junit-team/junit/wiki/Parameterized-tests">JUnit Parameterized Test Runner docs</a>
 */
@RunWith(Parameterized.class)
public class ExpectNoAltTagsInSellerNamesTest extends MultiLocaleParserTest {

    /**
     * Params that are filled for each localized test by the JUnit parameterized
     * test runner.  These go in order? or type/signature? based on the return
     * signature of data().
     */
    private String locale;
    private ArrayList fixtureData;
    private ArrayList expectedData;

    /**
     * Here is where you, the programmer, set up fixture data and expected results data
     * for each Amazon locale.  You then feed it to MultiLocaleParserTest#buildLocaleTestData
     * to transform it into a data structure for easy use by your actual test code.
     *
     * You must provide both fixture data and expected results for each test's Amazon locale
     * as an ArrayList with the Amazon locale as a String at element 0.
     *
     * Create an ArrayList of these locale-specific ArrayLists, as below, and feed it to
     * MultiLocalParserTest#buildLocaleTestDataArray() for your return value.
     *
     * The JUnit Parameterized Test Runner will then fill the private variables
     * #locale, #fixtureData, and #expectedData with the contents of each array
     * for every locale you define.
     *
     * NOTICE: JUnit 4.11+ should support an argument to the @Parameterized.Parameters()
     * annotiation which makes *which* test blew up when a particular test blows up more
     * understandable.  I was unable to get it to work, possibly due to old versions of
     * JUnit and/or Hamcrest Core.  The thing to paste in the parens is this:
     *
     *   name = "{index}: " + "expectProperHandlingOfImageSellerNames({0}) = {1}"
     *
     * cf. https://github.com/junit-team/junit/wiki/Parameterized-tests#identify-individual-test-cases
     * cf. http://youtrack.jetbrains.com/issue/IDEA-109891#comment=27-560090
     *
     * @return The value is described by MultiLocaleParserTest#buildLocaleTestDataArray()
     * @see MultiLocaleParserTest#buildLocaleTestDataArray(java.util.ArrayList, java.util.ArrayList)
     */
    @Parameterized.Parameters()
    public static Object[] data() throws Exception {
        ArrayList<ArrayList> fixtureList = new ArrayList<>();

        fixtureList.add(new ArrayList(Arrays.asList("UK", "/20130909-B0068ZAPB0-New--MST781.html")));
        fixtureList.add(new ArrayList(Arrays.asList("DE", "/20130909-B004LR5PRQ-New--MST781.html")));
        fixtureList.add(new ArrayList(Arrays.asList("FR", "/20130909-B001VL82J8-New--MST781.html")));

        ArrayList<ArrayList> expectedList = new ArrayList<>();
        expectedList.add(new ArrayList(Arrays.asList("UK", 10)));
        expectedList.add(new ArrayList(Arrays.asList("DE", 10)));
        expectedList.add(new ArrayList(Arrays.asList("FR", 10)));

        return buildLocaleTestDataArray(fixtureList, expectedList);
    }


    public void expectNoAltTagsInSellerNamesTest(String locale, ArrayList<Object> fixtureData, ArrayList<Object> expectedData) {
        this.locale = locale;
        this.fixtureData = fixtureData;
        this.expectedData = expectedData;
    }

    /**
     * Actual test code for this class.  Note the use of 'this.foo' variables,
     * which are stuffed by JUnit's Parameterized Test Runner before execution.
     *
     * There are a number of potential small refactors here.
     *
     * @throws Exception
     */
    @Test  // MST-781
    public void test() throws Exception {
        File htmlPage = named((String) this.fixtureData.get(0));
        assertThat(htmlPage, notNullValue());

        OfferList ol = getOfferList(htmlPage);
        assertThat(ol, notNullValue());

        int testVal = ol.getOffers().size();
        int expectVal = (Integer)this.expectedData.get(0);
        assertThat(testVal, is(expectVal));

        for (IOffer offer : ol.getOffers()) {
            String sellerName = offer.getSellerName();

            // look for seller names that have anything other than
            // \w (word chars), \s (whitespace), and [.,'"()&!-]
            // (in short, 'alt="Seller Name' should trigger this
            // @todo change to checking for "alt="
            Pattern pattern = Pattern.compile("[^\\w\\s.,'\"\\(\\)&!-]");
            Matcher matcher = pattern.matcher(sellerName);
//            System.out.println("Inspecting " + sellerName + ": " + matcher.find());
            assertThat(matcher.find(), is(false));
        }
    }

    public void smokeTest() throws Exception {
        // @todo derp
    }
}

回溯:

java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to java.util.List
at org.junit.runners.Parameterized.getParametersList(Parameterized.java:149)
at org.junit.runners.Parameterized.<init>(Parameterized.java:135)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at org.junit.internal.builders.AnnotatedBuilder.buildRunner(AnnotatedBuilder.java:31)
at org.junit.internal.builders.AnnotatedBuilder.runnerForClass(AnnotatedBuilder.java:24)
at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:57)
at org.junit.internal.builders.AllDefaultPossibilitiesBuilder.runnerForClass(AllDefaultPossibilitiesBuilder.java:29)
at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:57)
at org.junit.internal.requests.ClassRequest.getRunner(ClassRequest.java:24)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:44)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:195)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:63)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120)

进程结束，退出代码为 255

Answer 1

我假设您使用的是 JUnit 4.11。

@Parameters 方法

您必须更改代码的两个部分。首先是方法data()必须返回 Iterable<Object[]> ，但您返回的是 Object[] .这可以通过更改 buildLocaleTestDataArray 的最后一行来轻松解决。 :

Is: return testParamData.toArray();
Should be: return testParamData;

并更改方法的返回类型 buildLocaleTestDataArray和 data()至 Iterable<Object[]> .

分配参数

@Parameterized 不会自动分配参数。您可以使用@Parameter(index) 方法

@Parameter(0)
public String locale;
@Parameter(1)
public ArrayList fixtureData;
@Parameter(2)
public ArrayList expectedData;

或者改变方法expectNoAltTagsInSellerNamesTest进入构造函数

public ExpectNoAltTagsInSellerNamesTest(String locale, ArrayList<Object> fixtureData, ArrayList<Object> expectedData) {
    this.locale = locale;
    this.fixtureData = fixtureData;
    this.expectedData = expectedData;
}