...

To achieve this we mock DatabaseManager and we replace the connector to point to our in-memory database. In this class we also initialise the replica with the proper data.

Structure

Due to the Dspace Maven structure discussed in previous sections, all the tests belonging to any module (dspace-api, dspace-xmlui-api, etc) must be stored in the module dspace-test. This module enables us to apply common configuration, required by all tests, in a single area thus avoiding duplication of code. Related to this point is the requirement for Dspace to run using a database and a certain file system structure. We have created a base class that initializes this structure via a in-memory database (using H2) and a temporary copy of the required file system.

...

To build a new Unit Test, create the corresponding class in the project dspace-test, under the test folder, in the package where the original class belongs. Tests for all the projects (dspcedspace-api, dspace-jspui-api, etc) are stored in this project, to avoid duplication of code. Name the class following the format <OriginalClass>Test.java.

There are some common imports and structure, you can use the following code as a template:

package org.dspace.content;//Add DSpace licensing here at the top!
package org.dspace.content;

import java.sql.SQLException;
import org.dspace.core.Context;
import org.junit.*;
import static org.junit.Assert.* ;
import static org.hamcrest.CoreMatchers.*;
import mockit.*;
import org.apache.log4j.Logger;
import org.dspace.core.Constants;

/**
 * Unit Tests for class <OriginalClass>Test
 * @author you name
 */
public class <OriginalClass>Test extends AbstractUnitTest
{

    /** log4j category */
    private static final Logger log = Logger.getLogger(<OriginalClass>Test.class);

    /**
     * <OriginalClass> instance for the tests
     */
    private <OriginalClass> c;

    /**
     * This method will be run before every test as per @Before. It will
     * initialize resources required for the tests.
     *
     * Other methods can be annotated with @Before here or in subclasses
     * but no execution order is guaranteed
     */
    @Before
    @Override
    public void init()
    {
        super.init();
        try
        {
            //we have to create a new community in the database
            context.turnOffAuthorisationSystem();
            this.c = <OriginalClass>.create(null, context);


            //we need to commit the changes so we don't block the table for testing
            context.restoreAuthSystemState();
            context.commit();
        }
        catch (AuthorizeException ex)
        {
            log.error("Authorization Error in init", ex);
            fail("Authorization Error in init");
        }
        catch (SQLException ex)
        {
            log.error("SQL Error in init", ex);
            fail("SQL Error in init");
        }
    }

    /**
     * This method will be run after every test as per @After. It will
     * clean resources initialized by the @Before methods.
     *
     * Other methods can be annotated with @After here or in subclasses
     * but no execution order is guaranteed
     */
    @After
    @Override
    public void destroy()
    {
        c = null;
        super.destroy();
    }

    /**
     * Test of XXXX method, of class <OriginalClass>
     */
    @Test
    public void testXXXX() throws Exception
    {
        int id = c.getID();
        <OriginalClass> found =  <OriginalClass>.find(context, id);
        assertThat("testXXXX 0", found, notNullValue());
        assertThat("testXXXX 1", found.getID(), equalTo(id));
        assertThat("testXXXX 2", found.getName(), equalTo(""));
    }

   [... more tests ...]
}

...

mvn package  //builds DSpace and runs tests
  or
mvn test     //just runs the tests

Be aware that this command will launch both unit and integration tests.

Integration Tests

These tests work at the API level and test the interaction of components within the system. Some examples , are placing an item into a collection , or creating a new metadata schema and adding some fields. Primarily these tests operate at the API level ignoring the interface components above it.

...

The integration tests also make use of ContiPerf to evaluate the performance of the system. We believe it doesn't make sense to add this layer to the unit tests, as they are tested in isolation and we care about performance not on individual calls but on certain tasks that can only be emulated by integration testing.

Structure

Integration tests use the same structure as Unit tests. A class has been created, called AbstractIntegrationTest, that inherits from AbstractUnitTest. This provides the integration tests with the same temporal file system and in-memory database as the unit tests. The class AbstractIntegrationTest is created just in case we may need some extra scaffolding for these tests. All integration tests should inherit from it to both distinguish themselves from unit tests and in case we require specific changes for them.

Classes that contain teh the code for Integration Tests are named <class>IntegrationTest.java.

Events Concurrency Issues

We have detected an issue with the integration tests, related to the Context class. In this class, the List of events was implemented as an ArrayList<Event>. The issue here is that ArrayList is not a safe class for concurrency. Although this would not be a problem while running the application in a JEE container, as there will be a unique thread per request (at least in normal conditions), we can't be sure of the kind of calls users may do to the API while extending DSpace.

To avoid the issue we have to wrap the List into a synchronized stated via Collections.synchronizedList . This, along a synchronized block, will ensure the code behaves as expected.

We have detected the following classes affected by this behavior:

• BasicDispatcher.java

In fact any class that calls Context.getEvents() may be affected by this. A comment has been added in the javadoc of this class (alongside a TODO tag) to warn about the issue.

Context Concurrency Issues

There is another related issue in the Context class. Context establishes locks in the tables when doing some modifications, locks that are not lifted until the context is committed or completed. The consequence is that some methods can't be run in parallel or some executions will fail due to table locks. This can be solved, in some cases, by running context.commit() after a method that modifies the database, but this doesn't work in all cases. For example, in the CommunityCollection Integration Test, the creation of a community can mean the modification of 2 rows (parent and new community). This causes this kind of locks, but as it occurs during the execution of the method create() it can't be solved by context.commit().

The only difference right now between Unit Tests and Integration Tests is that the later include configuration settings for ContiPerf. These is a performance testing suite that allows us to reuse the same methods we use for integration testing as performance checks. Due to limitations mentioned in the following section we can't make use of all the capabilities of ContiPerf (namely, multiple threads to run the tests) but they can be still be useful.

Limitations

Tests structure

These limitations are shared with the unit tests.

The solution to copy the file system is not a very elegant one, so we appreciate any insight that can help us to replicate the required files appropriately.

The fact that we load the tests configuration from a dspace-test.cfg file means we are only testing the classes against a specific set of configurations. We probably would like to have tests that runs with multiple settings for the specific piece of code we are testing. This will require some extra classes to modify the configuration system and the way this is accessed by DSpace.

Events Concurrency Issues

We have detected an issue with the integration tests, related to the Context class. In this class, the List of events was implemented as an ArrayList<Event>. The issue here is that ArrayList is not a safe class for concurrency. Although this would not be a problem while running the application in a JEE container, as there will be a unique thread per request (at least in normal conditions), we can't be sure of the kind of calls users may do to the API while extending DSpace.

To avoid the issue we have to wrap the List into a synchronized stated via Collections.synchronizedList . This, along a synchronized block, will ensure the code behaves as expected.

We have detected the following classes affected by this behavior:

• BasicDispatcher.java

In fact any class that calls Context.getEvents() may be affected by this. A comment has been added in the javadoc of this class (alongside a TODO tag) to warn about the issue.

Context Concurrency Issues

There is another related issue in the Context class. Context establishes locks in the tables when doing some modifications, locks that are not lifted until the context is committed or completed. The consequence is that some methods can't be run in parallel or some executions will fail due to table locks. This can be solved, in some cases, by running context.commit() after a method that modifies the database, but this doesn't work in all cases. For example, in the CommunityCollection Integration Test, the creation of a community can mean the modification of 2 rows (parent and new community). This causes this kind of locks, but as it occurs during the execution of the method create() it can't be solved by context.commit().

Due to these concurrency issues, ContiPerf can only be run with one thread. This slows the process considerably, but until the concurrency issue is solved this can't be avoided.

How to build new tests

To build a new Integration Test, create the corresponding class in the project dspace-test, under the test folder, in the package where the original class belongs. Tests for all the projects (dspace-api, dspace-jspui-api, etc) are stored in this project, to avoid duplication of code. Name the class following the format <RelatedClasses>IntegrationTest.java.

There are some common imports and structure, you can use the following code as a template:

//Add DSpace licensing here at the top!
package org.dspace.content;

import java.sql.SQLException;
import org.dspace.core.Context;
import org.junit.*;
import static org.junit.Assert.* ;
import static org.hamcrest.CoreMatchers.*;
import mockit.*;
import org.apache.log4j.Logger;
import org.dspace.core.Constants;
/**
 * This is an integration test to validate the metadata classes
 * @author pvillega
 */
public class MetadataIntegrationTest  extends AbstractIntegrationTest
{
    /** log4j category */
    private static final Logger log = Logger.getLogger(MetadataIntegrationTest.class);


    /**
     * This method will be run before every test as per @Before. It will
     * initialize resources required for the tests.
     *
     * Other methods can be annotated with @Before here or in subclasses
     * but no execution order is guaranteed
     */
    @Before
    @Override
    public void init()
    {
        super.init();
    }

    /**
     * This method will be run after every test as per @After. It will
     * clean resources initialized by the @Before methods.
     *
     * Other methods can be annotated with @After here or in subclasses
     * but no execution order is guaranteed
     */
    @After
    @Override
    public void destroy()
    {
        super.destroy();
    }

    /**
     * Tests the creation of a new metadata schema with some values
     */
    @Test
    @PerfTest(invocations = 50, threads = 1)
    @Required(percentile95 = 500, average= 200)
    public void testCreateSchema() throws SQLException, AuthorizeException, NonUniqueMetadataException, IOException
    {
        String schemaName = "integration";

        //we create the structure
        context.turnOffAuthorisationSystem();
        Item it = Item.create(context);

        MetadataSchema schema = new MetadataSchema("htpp://test/schema/", schemaName);
        schema.create(context);
        [...]
        
        //commit to free locks on tables
        context.commit();

        //verify it works as expected
        assertThat("testCreateSchema 0", schema.getName(), equalTo(schemaName));
        assertThat("testCreateSchema 1", field1.getSchemaID(), equalTo(schema.getSchemaID()));
        assertThat("testCreateSchema 2", field2.getSchemaID(), equalTo(schema.getSchemaID()));              [...]
        //clean database
        value1.delete(context);
        [...]

        context.restoreAuthSystemState();
        context.commit();
    }

}

The sample code contains common imports for the tests and common structure (init and destroy methods as well as the log). You should add any initialization required for the test in the init method, and free the resources in the destroy method. 

The sample test shows the usage of the assertThat clause. This clause (more information in JUnit help) allows you to check for condition that, if not true, will cause the test to fail. We name every condition via a simple schema (method name plus an integer indicating order) as the first parameter. This allows you to identify which specific assert if failing whenever a test returns an error.

Please be aware methods init and destroy will run once per test, which means that if you create a new instance every time you run init, you may end up with several instances in the database. This can be confusing when implementing tests, specially when using methods like findAll.

If you want to add code that it's executed once per test class, edit the parent AbstractUnitTest and its methods initOnce and destroyOnce. Be aware these methods contain code used to recreate the structure needed to run DSpace tests, so be careful when adding or removing code there. Our suggestion is to add code at the end of initOnce and at the beginning of destroyOnce, to minimize the risk of interferences between components.

How to run the tests

The tests can be activated using the commands

mvn package -Dmaven.test.skip=false  //builds DSpace and runs tests
  or
mvn test -Dmaven.test.skip=false     //just runs the tests

or by changing the property "activeByDefault" at the profile (skiptests) in the main pom.xml file, at the root of the project and then running

mvn package  //builds DSpace and runs tests  
 or
mvn test     //just runs the tests

Be aware that this command will launch both unit and integration testsDue to these concurrency issues, ContiPerf can only be run with one thread. This slows the process considerably, but until the concurrency issue is solved this can't be avoided.

Code Analysis Tools

Due to comments in the GSoC meetings, some static analysis tools have been added to the project. The tools are just a complement, a platform like Sonar should be used as it integrates better with the structure of DSpace and we could have the reports linked to Jira.

...