使用querydsl模拟数据库查询-可选问题

Question

I've some difficulties to write tests on DB queries for my application, which uses querydsl on top of a mongo. I've found several examples of people who just unit-test the query object itself, but I'd like to go a step further and test how the query performs (like an integration test) BUT without having to start the whole DB process. That is, mocking the DB exclusively with java tools.

I couldn't find anything for that, tools such as DBUnit or DbSetup need an actual connection to DB. So I started to write my own classes, and it almost works. The idea is to use com.mysema.query.collections.CollQuery and mockito to simulate a database that would receive my application's queries, with a wrapper "CollQuery to Query". Basically, it works like this:

public class MyServiceTest {

    private MyService service;
    private final Collection<MyObject> fakeTable = new ArrayList<>();

    @Before
    public void setup() {

        final Persister persister = mock(Persister.class);
        when(persister.query(any(Class.class)))
                // MockedQuery is the wrapper I wrote
                .thenReturn(new MockedQuery<>(QMyObject.myObject, fakeTable));

        service = new MyService(persister);
    }

    @Test
    public void shouldWork() {
        fakeTable.add(new MyObject("one"));
        fakeTable.add(new MyObject("two"));
        fakeTable.add(new MyObject("three"));

        final List<MyObject> result = service.getOne();
        // service.getOne would do something like:
        //  persister.query(QMyObject.myObject).where(QMyObject.myObject.name.eq("one")).list()

        assertThat(result).hasSize(1);
    }
}

... and basically, it seems to work! Except that my code heavily uses guava's Optional, and it seems to be a problem for querydsl. If, instead of a String, MyObject takes an Optional < String > , then I get the error:

com.mysema.codegen.CodegenException: Compilation of public class     Q_01363784216_1275614662_1275614662_1573163836_01698119955_566403833 {

    public static Iterable<xxx.OpenedInterruption> eval(Iterable<xxx.OpenedInterruption> openedInterruption_, xxx.InterruptionType a1, xxx.InterruptionTargetType a2, com.google.common.base.Present a3) {
        java.util.List<xxx.OpenedInterruption> rv = new java.util.ArrayList<xxx.OpenedInterruption>();
        for (xxx.OpenedInterruption openedInterruption : openedInterruption_) {
            try {
                if (com.mysema.query.collections.CollQueryFunctions.equals(com.mysema.query.collections.CollQueryFunctions.<xxx.InterruptionType>get(openedInterruption, "type"), a1) && com.mysema.query.collections.CollQueryFunctions.equals(com.mysema.query.collections.CollQueryFunctions.<xxx.InterruptionTargetType>get(openedInterruption, "targetType"), a2) && com.mysema.query.collections.CollQueryFunctions.equals(com.mysema.query.collections.CollQueryFunctions.<com.google.common.base.Optional>get(openedInterruption, "target"), a3)) {
                    rv.add(openedInterruption);
                }
            } catch (NullPointerException npe) { }
        }
        return rv;    }

}

failed.
        /Q_01363784216_1275614662_1275614662_1573163836_01698119955_566403833.java:3: error: Present is not public in com.google.common.base; cannot be accessed from outside package
public static Iterable<xxx.OpenedInterruption> eval(Iterable<xxx.OpenedInterruption> openedInterruption_, xxx.InterruptionType a1, xxx.InterruptionTargetType a2, com.google.common.base.Present a3) {
        ^
        1 error

        at com.mysema.codegen.JDKEvaluatorFactory.compile(JDKEvaluatorFactory.java:74)
        at com.mysema.codegen.AbstractEvaluatorFactory.createEvaluator(AbstractEvaluatorFactory.java:128)
        at com.mysema.query.collections.DefaultEvaluatorFactory.createEvaluator(DefaultEvaluatorFactory.java:157)
        at com.mysema.query.collections.DefaultQueryEngine.evaluateSingleSource(DefaultQueryEngine.java:176)
        at com.mysema.query.collections.DefaultQueryEngine.list(DefaultQueryEngine.java:91)
        at com.mysema.query.collections.AbstractCollQuery.list(AbstractCollQuery.java:219)
        at xxx.BusinessInterruptionServiceImplTest$MockedQuery.list(BusinessInterruptionServiceImplTest.java:143)
        at xxx.BusinessInterruptionServiceImplTest.setup(BusinessInterruptionServiceImplTest.java:79)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
        at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
        at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
        at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:24)
        at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
        at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
        at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
        at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
        at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
        at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
        at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
        at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
        at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
        at org.junit.runner.JUnitCore.run(JUnitCore.java:160)
        at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:74)
        at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:211)
        at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:67)
        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:134)

So, it looks like mysema tries to instanciate com.google.common.base.Present , but is unable to do so. The weird part is that the same query works perfectly with my production code, so maybe the problem is very specific to the "CollQuery" class I use for mocking.

Any idea about how to solve this?

Or alternatively, if someone can see a different way to mock the DB like I'm trying to do, I would appreciate any help!

Thanks

PS: here's my wrapper "MockedQuery" class (quite straightforward):

public class MockedQuery<T> implements Query<T> {

    private final Path<T> path;
    private final CollQuery collQuery;

    public MockedQuery(final Path<T> path, final Iterable<T> collection) {
        this.path = path;
        collQuery = from(path, collection);
    }

    @Override
    public boolean exists() {
        return collQuery.exists();
    }

    @Override
    public boolean notExists() {
        return !exists();
    }

    @Override
    public CloseableIterator<T> iterate() {
        return collQuery.iterate(path);
    }

    @Override
    public List<T> list() {
        return collQuery.list(path);
    }

    @Nullable
    @Override
    public T singleResult() {
        return collQuery.singleResult(path);
    }

    @Nullable
    @Override
    public T uniqueResult() {
        return collQuery.uniqueResult(path);
    }

    @Override
    public SearchResults<T> listResults() {
        return collQuery.listResults(path);
    }

    @Override
    public long count() {
        return collQuery.count();
    }

    @Override
    public Query<T> limit(final long limit) {
        collQuery.limit(limit);
        return this;
    }

    @Override
    public Query<T> offset(final long offset) {
        collQuery.offset(offset);
        return this;
    }

    @Override
    public Query<T> restrict(final QueryModifiers modifiers) {
        collQuery.restrict(modifiers);
        return this;
    }

    @Override
    public Query<T> orderBy(final OrderSpecifier<?>... o) {
        collQuery.orderBy(o);
        return this;
    }

    @Override
    public <U> Query<T> set(final ParamExpression<U> param, final U value) {
        collQuery.set(param, value);
        return this;
    }

    @Override
    public Query<T> distinct() {
        collQuery.distinct();
        return this;
    }

    @Override
    public Query<T> where(final Predicate... o) {
        collQuery.where(o);
        return this;
    }
}

Answer 1

有关信息，它已在querydsl 3.6.3中修复。