用于连接到数据库的Rest API的Junit测试用例

Question

I have a JAVA rest service that interacts with the database , does some manipulation and returns the data.

I am trying to write test cases for these APIs.

I am trying to use the below link for reference to implement this.

http://www.developer.com/java/other/article.php/10936_3882311_2/Mockito-Java-Unit-Testing-with-Mock-Objects.htm

Here, calls made to the database are suppressed and the dto is mocked with made up values.

Is there an alternate method where we actually get to run the queries w/o talking to the db , (an in-memory db may be? )

Any code sample or reference would be of great help.

Answer 1

HSQLDB is one in memory db i'm familiar with. The examples showed here against HSQLDB used with hibernate and JPA. http://uaihebert.com/tdd-with-hsqldb-jpa-and-hibernate/ .

However i think it'll be useful to ask why you would prefer connecting to an in memory db than mocking the db in your situation? It boils down to what scope of testing unit/integration you are trying to achieve. What are you trying to test the manupilation logic in the rest layer? Where mocking is sufficient. Are you trying to test how the rest handles the data access behavior, such as db error handling etc, than in memory might be slightly better. Is the thing you are testing dependent on data setup/ testing data setup , in which case in memory db might be closer, since you can use the same/similar sql creation to test in inmemory db.

Answer 2

For a pure HashMap solution, something like this would work though then you would loose access to SQL query functionality (unless you mock the query too).

public class MockDatabase<T> {

protected Map<Serializable, T> fakeDatabase = Maps.newHashMap();

private final CustomRepository<T,Serializable> repository;

private Validator validator;

public void setValidator(Validator validator) {
    this.validator = validator;
}

public static <T extends CustomRepository> T mock(Class<T> classToMock, Validator validator) {

    T repository = Mockito.mock(classToMock);
    MockDatabase md = new MockDatabase<T>(repository, validator);

    return repository;
}


public <ID extends Serializable> MockDatabase(CustomRepository<T, ID> repository, Validator validator){
    this.repository = (CustomRepository<T, Serializable>) repository;
    this.validator = validator;


    reset(repository);
    doAnswer(new Answer<Object>() {
        @Override
        public Object answer(InvocationOnMock invocation) throws Throwable {
            fakeDatabase.clear();
            return null;
        }
    }).when(repository).deleteAll();

    when(repository.save((T) anyObject())).thenAnswer(new Answer<T>() {
        @Override
        public T answer(InvocationOnMock invocation) throws Throwable {
            return saveOrSaveAndFlush(invocation);
        }
    });


    when(repository.getReference((ID)anyObject())).thenAnswer(new Answer<T>() {
        @Override
        public T answer(InvocationOnMock invocation) throws Throwable {
            return fakeDatabase.get(invocation.getArguments()[0]);
        }
    });

   when(repository.findOne((ID)anyObject())).thenAnswer(new Answer<T>() {
       @Override
       public T answer(InvocationOnMock invocation) throws Throwable {
           return fakeDatabase.get(invocation.getArguments()[0]);
       }
   });

    doAnswer(new Answer<T>() {
        @Override
        public T answer(InvocationOnMock invocation) throws Throwable {
            return fakeDatabase.remove(ReflectionTestUtils.invokeGetterMethod(invocation.getArguments()[0], "getId"));
        }
    }).when(repository).delete((T)anyObject());


    doAnswer(new Answer<ID>() {
        @Override
        public ID answer(InvocationOnMock invocation) throws Throwable {
           fakeDatabase.remove(((ID)invocation.getArguments()[0]));
            return null;
        }
    }).when(repository).delete((ID)anyObject());


    when(repository.saveAndFlush((T) anyObject())).thenAnswer(new Answer<T>() {
        @Override
        public T answer(InvocationOnMock invocation) throws Throwable {
            return saveOrSaveAndFlush(invocation);
        }


    });

    when(repository.exists((ID)anyObject())).thenAnswer(new Answer<Boolean>() {
        @Override
        public Boolean answer(InvocationOnMock invocation) throws Throwable {
            return fakeDatabase.containsKey(invocation.getArguments()[0]);
        }
    });


    when(repository.merge(anyObject())).thenAnswer(new Answer<T>() {
        @Override
        public T answer(InvocationOnMock invocation) throws Throwable {
            return (T) invocation.getArguments()[0];
        }
    });


    when(repository.findAll()).thenAnswer(new Answer<List<T>>() {
        @Override
        public List<T> answer(InvocationOnMock invocation) throws Throwable {
            return Lists.newLinkedList(fakeDatabase.values());
        }
    });

    customMethods();

}

private T saveOrSaveAndFlush(InvocationOnMock invocation) throws NoSuchMethodException {
    Object[] args = invocation.getArguments();
    Serializable id = (Serializable) ReflectionTestUtils.getField(args[0], "id");
    if (id == null) {
        Class<?> returnType = args[0].getClass().getMethod("getId").getReturnType();

        if (returnType.equals(Long.class)) {
            id = (Long) new Random().nextLong();
        } else if (returnType.equals(Integer.class)) {
            id = (Integer) new Random().nextInt();
        }
        ReflectionTestUtils.setField(args[0], "id", id);
    }

    Set<ConstraintViolation<T>> validations = validator.validate((T)args[0]);
    if (!validations.isEmpty()){
        throw new IllegalStateException("Object failed validations (it would also fail on a db): "+validations);
    }
    for (Method method: args[0].getClass().getDeclaredMethods()){
        if (method.isAnnotationPresent(Basic.class)){
            Annotation a = method.getAnnotation(Basic.class);
            if (!(boolean) AnnotationUtils.getValue(method.getAnnotation(Basic.class), "optional")){
                if (ReflectionTestUtils.invokeGetterMethod(args[0], method.getName()) == null){
                   throw new IllegalStateException(args[0].getClass().getSimpleName()+"."+method.getName() + " returned null, but marked with @Basic(optional=false) - it would also fail on a db: "+validations);

                }
            }
        }
    }
    fakeDatabase.put(id, (T) args[0]);

    return (T) args[0];
}

public void customMethods() {
    // override here if you want
}

}

If you had @Entity annotated POJOs, then with say hibernate library you can ask it to export to HSQLDB script and then use that. Eg you export via:

Configuration configuration = new Configuration();
        try {
            classes().forEach(cl -> {
                configuration.addAnnotatedClass(cl);
            });
            configuration.setProperty("hibernate.dialect", HSQLCustomDialect.class.getName());
            SchemaExport schemaExport = new SchemaExport(configuration);
            schemaExport.setOutputFile("someFileName.sql");
            schemaExport.setFormat(false);
            schemaExport.setDelimiter(";");
            schemaExport.execute(true, false, false, true);

and thereafter you would use spring to insert that SQL script for you:

@ActiveProfiles("test")
@SqlConfig(transactionMode = SqlConfig.TransactionMode.ISOLATED)
 @SqlGroup({
    @Sql(statements = "DROP SCHEMA PUBLIC CASCADE"),
    @Sql(scripts = "classpath:yourGeneratedSQL.sql"),
})

public class DAOIntegrationTest {