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Alex Soto discovered Java during second year of his studies in computer science and wrote his Master's Thesis on Emergent Intelligence applied to Data Mining, winning the second prize of Hermano Salvador González contest. During his 11 years of software development, Alex has worked in several companies as technical consultant, and currently is working as technical analyst at a major international pharmaceutical company developing in-vitro medical software meeting FDA standards, where performance and safety is "a must". Alex also works as tutor at Open University of Catalonia (UOC), teaching Compilers course. He spends his free time to write in his blog (http://www.lordofthejars.com) where some posts are published in sites like dzone, theserverside and springsource. Alex has spoken at Devoxx 2011 and Linuxtag 2012. Currently is developing NoSQLUnit, a JUnit extension for testing NoSQL systems. Alex is a DZone MVB and is not an employee of DZone and has posted 32 posts at DZone. You can read more from them at their website. View Full User Profile

Testing Spring Data MongoDB Apps with NoSQL Unit

01.01.2013
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Spring Data MongoDB

Spring Data MongoDB is the project within Spring Data project which provides an extension to the Spring programming model for writing applications that uses MongoDB as database. To write tests using NoSQLUnit for Spring Data MongoDB applications, you do need nothing special apart from considering that Spring Data MongoDB uses a special property called _class for storing type information alongside the document. _class property stores the fully qualified classname inside the document for the top-level document as well as for every value if it is a complex type.
Note Type mapping
MappingMongoConverter is used as default type mapping implementation but you can customize even more using @TypeAlias or implementing TypeInformationMapper interface.

Application

Starfleet has asked us to develop an application for storing all logs of starship crew members into their systems. To implement this requirement we are going to use MongoDB database as backend system and Spring Data MongoDB at persistence layer. Log documents have next json format:
Example of Log Document

{
        "_class" : "com.lordofthejars.nosqlunit.springdata.mongodb.log.Log" ,
        "_id" : 1 ,
        "owner" : "Captain" ,
        "stardate" : {
                "century" : 4 ,
                "season" : 3 ,
                "sequence" : 125 ,
                "day" : 8
        } ,
        "messages" : [
                        "We have entered a spectacular binary star system in the Kavis Alpha sector on a most critical mission of astrophysical research. Our eminent guest, Dr. Paul Stubbs, will attempt to study the decay of neutronium expelled at relativistic speeds from a massive stellar explosion which will occur here in a matter of hours." ,
                        "Our computer core has clearly been tampered with and yet there is no sign of a breach of security on board. We have engines back and will attempt to complete our mission. But without a reliable computer, Dr. Stubbs' experiment is in serious jeopardy."
        ]
}

This document is modelized into two Java classes, one for whole document and another one for stardate part.

Stardate class

@Document
public class Stardate {

        private int century;
        private int season;
        private int sequence;
        private int day;

        public static final Stardate createStardate(int century, int season, int sequence, int day) {

                Stardate stardate = new Stardate();

                stardate.setCentury(century);
                stardate.setSeason(season);
                stardate.setSequence(sequence);
                stardate.setDay(day);

                return stardate;

        }

        //Getters and Setters
}


@Document
public class Stardate {

        private int century;
        private int season;
        private int sequence;
        private int day;

        public static final Stardate createStardate(int century, int season, int sequence, int day) {

                Stardate stardate = new Stardate();

                stardate.setCentury(century);
                stardate.setSeason(season);
                stardate.setSequence(sequence);
                stardate.setDay(day);

                return stardate;

        }

        //Getters and Setters
}
Log class

@Document
public class Log {

        @Id
        private int logId;

        private String owner;
        private Stardate stardate;

        private List<String> messages = new ArrayList<String>();

        //Getters and Setters
}

Apart from model classes, we also need a DAO class for implementing CRUD operations, and spring application context file. MongoLogManager class

@Repository
public class MongoLogManager implements LogManager {

        private MongoTemplate mongoTemplate;

        public void create(Log log) {
                this.mongoTemplate.insert(log);
        }

        public List<Log> findAll() {
                return this.mongoTemplate.findAll(Log.class);
        }

        @Autowired
        public void setMongoTemplate(MongoTemplate mongoTemplate) {
                this.mongoTemplate = mongoTemplate;
        }

}


@Repository
public class MongoLogManager implements LogManager {

        private MongoTemplate mongoTemplate;

        public void create(Log log) {
                this.mongoTemplate.insert(log);
        }

        public List<Log> findAll() {
                return this.mongoTemplate.findAll(Log.class);
        }

        @Autowired
        public void setMongoTemplate(MongoTemplate mongoTemplate) {
                this.mongoTemplate = mongoTemplate;
        }

}
application-context file

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context-3.1.xsd">

     <context:component-scan base-package="com.lordofthejars.nosqlunit.springdata.mongodb"/>
     <context:annotation-config/>

</beans>

Tip For this example we have used MongoTemplate class for accessing to MongoDB to not create an overcomplicated example, but in a bigger project I recommend use Spring Data Repository approach by implementing CrudRepository interface on manager classes.

Testing

As has been told previously, you don’t have to do anything special beyond using class property correctly. Let’s see the dataset used to test the findAll method by seeding _log collection of logs database.
all-logs file

{
        "log":[
                {
                        "_class" : "com.lordofthejars.nosqlunit.springdata.mongodb.log.Log" ,
                        "_id" : 1 ,
                        "owner" : "Captain" ,
                        "stardate" : {
                                "century" : 4 ,
                                "season" : 3 ,
                                "sequence" : 125 ,
                                "day" : 8
                        } ,
                        "messages" : [
                                "We have entered a spectacular binary star system in the Kavis Alpha sector on a most critical mission of astrophysical research. Our eminent guest, Dr. Paul Stubbs, will attempt to study the decay of neutronium expelled at relativistic speeds from a massive stellar explosion which will occur here in a matter of hours." ,
                                "Our computer core has clearly been tampered with and yet there is no sign of a breach of security on board. We have engines back and will attempt to complete our mission. But without a reliable computer, Dr. Stubbs' experiment is in serious jeopardy."
                        ]
                }
                ,
                {
                        "_class" : "com.lordofthejars.nosqlunit.springdata.mongodb.log.Log" ,
                        "_id" : 2 ,
                        "owner" : "Captain" ,
                        "stardate" : {
                                "century" : 4 ,
                                "season" : 3 ,
                                "sequence" : 152 ,
                                "day" : 4
                        } ,
                        "messages" : [
                                "We are cautiously entering the Delta Rana star system three days after receiving a distress call from the Federation colony on its fourth planet. The garbled transmission reported the colony under attack from an unidentified spacecraft. Our mission is one of rescue and, if necessary, confrontation with a hostile force."
                        ]
                }
                ...
}

See that _class property is set to full qualified name of Log class. Next step is configuring MongoTemplate for test execution.
LocalhostMongoAppConfig
@Configuration
@Profile("test")
public class LocalhostMongoAppConfig {

        private static final String DATABASE_NAME = "logs";

        public @Bean Mongo mongo() throws UnknownHostException, MongoException {
                Mongo mongo = new Mongo("localhost");
                return mongo;
        }

        public @Bean MongoTemplate mongoTemplate() throws UnknownHostException, MongoException {
                MongoTemplate mongoTemplate = new MongoTemplate(mongo(), DATABASE_NAME);
                return mongoTemplate;
        }

}

Notice that this MongoTemplate object will be instantiated only when test profile is active. And now we can write the JUnit test case: WhenAlmiralWantsToReadLogs
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:com/lordofthejars/nosqlunit/springdata/mongodb/log/application-context-test.xml")
@ActiveProfiles("test")
@UsingDataSet(locations = "all-logs.json", loadStrategy = LoadStrategyEnum.CLEAN_INSERT)
public class WhenAlmiralWantsToReadLogs {

        @ClassRule
        public static ManagedMongoDb managedMongoDb = newManagedMongoDbRule()
                        .mongodPath(
                                        "/Users/alexsotobueno/Applications/mongodb-osx-x86_64-2.0.5")
                        .build();

        @Rule
        public MongoDbRule mongoDbRule = newMongoDbRule().defaultManagedMongoDb("logs");

        @Autowired
        private LogManager logManager;

        @Test
        public void all_entries_should_be_loaded() {

                List<Log> allLogs = logManager.findAll();
                assertThat(allLogs, hasSize(3));

        }

}

There are some important points in the previous class to take a look:
  1. Because NoSQLUnit uses JUnit Rules you can use @RunWith(SpringJUnit4ClassRunner) freely.
  2. Using @ActiveProfiles we are loading the test configuration instead of the production ones.
  3. You can use Spring annotations like @Autowired without any problem.

Conclusions

There is not much difference between writing tests for none Spring Data MongoDB and applications that use it. Only keep in mind to define correctly the _class property.

We keep learning,
Alex.
Els astronautes volen baix, Els núvols passen com qui no diu res. Amb les butxaques a les mans, Caminarem els passos d’altres peus. (Pa amb Oli i Sal - Blaumut)

Published at DZone with permission of Alex Soto, author and DZone MVB. (source)

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