Custom SonarQube rules for Unit Tests

I need a new rule

In our project we use (formely Sonar) to manage our code quality. It is a great tool and I recommend everyone to set it up and read its reports.

Recently, we've agreed that it's better to use assertj assertions in our unit tests than JUnit's. So I've decided to write a simple rule that checks if some of JUnit asserts assertTrue, assertFalse, assertNull and others are used. Then, I've discovered it's not so easy to do it with Sonar:

  • only 10 code quality rules are applied to unit tests - they are in special repository PMD Unit Tests (source)
  • these 10 rules are disabled by default, you have to enable them by hand
  • you cannot add new rules to this group

However, it turned out it is doable with a small tricks.

Custom PMD Unit Tests rule tutorial

Create your XPath expression by following this tutorial on how to create custom PMD rule. There is a visual editor to test your rules as you develop them - that's great. My XPath expression to avoid all JUnit assertions looks like this:

//PrimaryPrefix/Name[@Image='assertEquals' or @Image='assertNull' or @Image='assertNotNull' or @Image='assertSame' or @Image='assertNotSame' or @Image='assertArrayEquals' or @Image='assertTrue' or @Image='assertFalse']

Go to your Sonar installation, log in as an Administrator, head to Quality Profiles and select a profile that you use. Search for "xpath" and change Activation to Any. You should see two results like this:

Expand XPath rule template (dont' worry that it says it's deprecated) and then click Copy rule. Fill a form with message and XPath and save it. Then take a look at the bottom - you need an identifier of this rule:

You have created a PMD rule, now you need to move it to PMD Unit Tests group. Connect to Sonar's MySQL database. Search for your rule by key:

mysql> select id, plugin_rule_key, plugin_name, parent_id, status from rules where plugin_rule_key='XPathRule_1385721910';
+-----+----------------------+----------------+-----------+-------------+
| id | plugin_rule_key | plugin_name | parent_id | status |
+-----+----------------------+----------------+-----------+-------------+
| 903 | XPathRule_1385721910 | pmd | NULL | DEPRECATED |
+-----+----------------------+----------------+-----------+-------------+
1 row in set (0.00 sec)

Update plugin_name and status (remember to use appropiate primary key for id column):

mysql> update rules set plugin_name='pmd-unit-tests', status='READY' where id=903;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0

There is one step left. Sonar will change this rule's status to REMOVED on restart due to his boot checks. You need to trick him and change parent_id to other's PMD Unit Tests rule. List all these rules and choose one's identifier.

mysql> select id, plugin_name, status from rules where plugin_name='pmd-unit-tests';
+-----+----------------+---------+
| id | plugin_name | status |
+-----+----------------+---------+
| 775 | pmd-unit-tests | READY |
| 776 | pmd-unit-tests | READY |
| 777 | pmd-unit-tests | READY |
| 778 | pmd-unit-tests | READY |
| 779 | pmd-unit-tests | READY |
| 780 | pmd-unit-tests | READY |
| 781 | pmd-unit-tests | READY |
| 782 | pmd-unit-tests | READY |
| 783 | pmd-unit-tests | READY |
| 784 | pmd-unit-tests | READY |
| 903 | pmd-unit-tests | READY |
+-----+----------------+---------+
11 rows in set (0.00 sec)

Choose any id you like, let's say 775 and apply it as parent_id to your newly created rule:

mysql> update rules set parent_id=775 where id=903;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0

Go to your Quality profile and make sure your rule is active! Check it twice, it's easy to forget that step. It's all set up, enjoy your analysis!

Custom SonarQube rules for Unit Tests

I need a new rule

In our project we use (formely Sonar) to manage our code quality. It is a great tool and I recommend everyone to set it up and read its reports.

Recently, we've agreed that it's better to use assertj assertions in our unit tests than JUnit's. So I've decided to write a simple rule that checks if some of JUnit asserts assertTrue, assertFalse, assertNull and others are used. Then, I've discovered it's not so easy to do it with Sonar:

  • only 10 code quality rules are applied to unit tests - they are in special repository PMD Unit Tests (source)
  • these 10 rules are disabled by default, you have to enable them by hand
  • you cannot add new rules to this group

However, it turned out it is doable with a small tricks.

Custom PMD Unit Tests rule tutorial

Create your XPath expression by following this tutorial on how to create custom PMD rule. There is a visual editor to test your rules as you develop them - that's great. My XPath expression to avoid all JUnit assertions looks like this:

//PrimaryPrefix/Name[@Image='assertEquals' or @Image='assertNull' or @Image='assertNotNull' or @Image='assertSame' or @Image='assertNotSame' or @Image='assertArrayEquals' or @Image='assertTrue' or @Image='assertFalse']

Go to your Sonar installation, log in as an Administrator, head to Quality Profiles and select a profile that you use. Search for "xpath" and change Activation to Any. You should see two results like this:

Expand XPath rule template (dont' worry that it says it's deprecated) and then click Copy rule. Fill a form with message and XPath and save it. Then take a look at the bottom - you need an identifier of this rule:

You have created a PMD rule, now you need to move it to PMD Unit Tests group. Connect to Sonar's MySQL database. Search for your rule by key:

mysql> select id, plugin_rule_key, plugin_name, parent_id, status from rules where plugin_rule_key='XPathRule_1385721910';
+-----+----------------------+----------------+-----------+-------------+
| id | plugin_rule_key | plugin_name | parent_id | status |
+-----+----------------------+----------------+-----------+-------------+
| 903 | XPathRule_1385721910 | pmd | NULL | DEPRECATED |
+-----+----------------------+----------------+-----------+-------------+
1 row in set (0.00 sec)

Update plugin_name and status (remember to use appropiate primary key for id column):

mysql> update rules set plugin_name='pmd-unit-tests', status='READY' where id=903;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0

There is one step left. Sonar will change this rule's status to REMOVED on restart due to his boot checks. You need to trick him and change parent_id to other's PMD Unit Tests rule. List all these rules and choose one's identifier.

mysql> select id, plugin_name, status from rules where plugin_name='pmd-unit-tests';
+-----+----------------+---------+
| id | plugin_name | status |
+-----+----------------+---------+
| 775 | pmd-unit-tests | READY |
| 776 | pmd-unit-tests | READY |
| 777 | pmd-unit-tests | READY |
| 778 | pmd-unit-tests | READY |
| 779 | pmd-unit-tests | READY |
| 780 | pmd-unit-tests | READY |
| 781 | pmd-unit-tests | READY |
| 782 | pmd-unit-tests | READY |
| 783 | pmd-unit-tests | READY |
| 784 | pmd-unit-tests | READY |
| 903 | pmd-unit-tests | READY |
+-----+----------------+---------+
11 rows in set (0.00 sec)

Choose any id you like, let's say 775 and apply it as parent_id to your newly created rule:

mysql> update rules set parent_id=775 where id=903;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0

Go to your Quality profile and make sure your rule is active! Check it twice, it's easy to forget that step. It's all set up, enjoy your analysis!

Grails with Spock unit test + IntelliJ IDEA = No thread-bound request found

During my work with Grails project using Spock test in IntelliJ IDEA I've encountered this error:
 
java.lang.IllegalStateException: No thread-bound request found: Are you referring to request attributes outside of an actual web request, or processing a request outside of the originally receiving thread? If you are actually operating within a web request and still receive this message, your code is probably running outside of DispatcherServlet/DispatcherPortlet: In this case, use RequestContextListener or RequestContextFilter to expose the current request.
 at org.springframework.web.context.request.RequestContextHolder.currentRequestAttributes(RequestContextHolder.java:131)
 at org.codehaus.groovy.grails.plugins.web.api.CommonWebApi.currentRequestAttributes(CommonWebApi.java:205)
 at org.codehaus.groovy.grails.plugins.web.api.CommonWebApi.getParams(CommonWebApi.java:65)
... // and few more lines of stacktrace ;)
 
It occurred when I tried to debug one of test from IDEA level. What is interesting, this error does not happen when I'm running all test using grails test-app for instance.
 
So what was the issue? With little of reading and tip from Tomek Kalkosiński (http://refaktor.blogspot.com/) it turned out that our test was missing @TestFor annotation and adding it solved all problems. This annotation, according to Grails docs (link), indicates Spock what class is being tested and implicitly creates field with given type in test class. It is somehow strange as problematic test had explicitly and "manually" created field with proper controller type. Maybe there is a problem with mocking servlet requests?

Spock basics

Spock (homepage) is like its authors say 'testing and specification framework'. Spock combines very elegant and natural syntax with the powerful capabilities. And what is most important it is easy to use.

One note at the very beginning: I assume that you are already familiar with principles of Test Driven Development and you know how to use testing framework like for example JUnit.

So how can I start?

 
Writing spock specifications is very easy. We need basic configuration of Spock and Groovy dependencies (if you are using mavenized project with Eclipse look to my previous post: Spock, Java and Maven). Once we have everything set up and running smooth we can write our first specs (spec or specification is equivalent for test class in other frameworks like JUnit of TestNG). What is great with Spock is fact that we can use it to test both Groovy projects and pure Java projects or even mixed projects.
 

Let's go!

Every spec class must inherit from spock.lang.Specification class. Only then test runner will recognize it as test class and start tests. We will write few specs for this simple class: User class and few tests not connected with this particular class.
We start with defining our class:
import spock.lang.*

class UserSpec extends Specification {

}
Now we can proceed to defining test fixtures and test methods.
All activites we want to perform before each test method, are to be put in def setup() {...} method and everything we want to be run after each test should be put in def cleanup() {...} method (they are equivalents for JUnit methods with @Before and @After annotations).
It can look like this:
class UserSpec extends Specification {
    User user
    Document document

    def setup() {
        user = new User()
        document = DocumentTestFactory.createDocumentWithTitle("doc1")
    }

    def cleanup() {

    }
}
Of course we can use field initialization for instantiating test objects:
class UserSpec extends Specification {
    User user = new User()
    Document document = DocumentTestFactory.createDocumentWithTitle("doc1")

    def setup() {

    }

    def cleanup() {

    }
}
 
What is more readable or preferred? It is just a matter of taste because according to Spock docs behaviour is the same in these two cases.
It is worth mentioning that JUnit @BeforeClass/@AfterClass are also present in Spock as def setupSpec() {...} and def cleanupSpec() {...}. They will be runned before first test and after last test method.
 

First tests

In Spock every method in specification class, expect setup/cleanup, is treated by runner as a test method (unless you annotate it with @Ignore).
Very interesting feature of Spock and Groovy is ability to name methods with full sentences just like regular strings:
class UserSpec extends Specification {
    // ...

    def "should assign coment to user"() {
        // ...
    }
}
With such naming convention we can write real specification and include details about specified behaviour in method name, what is very convenient when reading test reports and analyzing errors. Test method (also called feature method) is logically divided into few blocks, each with its own purpose. Blocks are defined like labels in Java (but they are transformed with Groovy AST transform features) and some of them must be put in code in specific order. Most basic and common schema for Spock test is:
class UserSpec extends Specification {
    // ...

    def "should assign coment to user"() {
        given:
            // do initialization of test objects
        when:
            // perform actions to be tested
        then:
            // collect and analyze results
    }
}
But there are more blocks like:
  • setup
  • expect
  • where
  • cleanup
In next section I am going to describe each block shortly with little examples.

given block

This block is used to setup test objects and their state. It has to be first block in test and cannot be repeated. Below is little example how can it be used:
class UserSpec extends Specification {
    // ...
    
    def "should add project to user and mark user as project's owner"() {
        given:
            User user = new User()
            Project project = ProjectTestFactory.createProjectWithName("simple project")
        // ...
    }
}
In this code given block contains initialization of test objects and nothing more. We create simple user without any specified attributes and project with given name. In case when some of these objects could be reused in more feature methods, it could be worth putting initialization in setup method.

when and then blocks

When block contains action we want to test (Spock documentation calls it 'stimulus'). This block always occurs in pair with then block, where we are verifying response for satisfying certain conditions. Assume we have this simple test case:
class UserSpec extends Specification {
    // ...
    
    def "should assign user to comment when adding comment to user"() {
        given:
            User user = new User()
            Comment comment = new Comment()
        when:
            user.addComment(comment)
        then:
            comment.getUserWhoCreatedComment().equals(user)
    }

    // ...
}
In when block there is a call of tested method and nothing more. After we are sure our action was performed, we can check for desired conditions in then block. Then block is very well structured and its every line is treated by Spock as boolean statement. That means, Spock expects that we write instructions containing comparisons and expressions returning true or false, so we can create then block with such statements:
user.getName() == "John"
user.getAge() == 40
!user.isEnabled()
Each of lines will be treated as single assertion and will be evaluated by Spock. Sometimes we expect that our method throws an exception under given circumstances. We can write test for it with use of thrown method:
class CommentSpec extends Specification {
    def "should throw exception when adding null document to comment"() {
        given:
            Comment comment = new Comment()
        when:
            comment.setCommentedDocument(null)
        then:
            thrown(RuntimeException)
    }
}
In this test we want to make sure that passing incorrect parameters is correctly handled by tested method and that method throws an exception in response. In case you want to be certain that method does not throw particular exception, simply use notThrown method.

expect block

Expect block is primarily used when we do not want to separate when and then blocks because it is unnatural. It is especially useful for simple test (and according to TDD rules all test should be simple and short) with only one condition to check, like in this example (it is simple but should show the idea):
def "should create user with given name"() {
    given:
        User user = UserTestFactory.createUser("john doe")
    expect:
        user.getName() == "john doe"
}
 

More blocks!

That were very simple tests with standard Spock test layout and canonical divide into given/when/then parts. But Spock offers more possibilities in writing tests and provides more blocks.

setup/cleanup blocks

These two blocks have the very same functionality as the def setup and def cleanup methods in specification. They allow to perform some actions before test and after test. But unlike these methods (which are shared between all tests) blocks work only in methods they are defined in. 

 

where - easy way to create readable parameterized tests

Very often when we create unit tests there is a need to "feed" them with sample data to test various cases and border values. With Spock this task is very easy and straighforward. To provide test data to feature method, we need to use where block. Let's take a look at little the piece of code:
def "should successfully validate emails with valid syntax"() {
    expect:
        emailValidator.validate(email) == true
    where:
        email << [ "test@test.com", "foo@bar.com" ]
}
In this example, Spock creates variable called email which is used when calling method being tested. Internally feature method is called once, but framework iterates over given values and calls expect/when block as many times as there are values (however, if we use @Unroll annotation Spock can create separate run for each of given values, more about it in one of next examples). Now, lets assume that we want our feature method to test both successful and failure validations. To achieve that goal we can create few parameterized variables for both input parameter and expected result. Here is a little example:
def "should perform validation of email addresses"() {
    expect:
        emailValidator.validate(email) == result
    where:
        email << [ "WTF", "@domain", "foo@bar.com" "a@test" 
        result << [ false, false, true, false ]
}
Well, it looks nice, but Spock can do much better. It offers tabular format of defining parameters for test what is much more readable and natural. Lets take a look:
def "should perform validation of email addresses"() {
    expect:
        emailValidator.validate(email) == result
    where:
        email           | result
        "WTF"           | false
        "@domain"       | false
        "foo@bar.com"   | true
        "a@test"        | false
}
In this code, each column of our "table" is treated as a separate variable and rows are values for subsequent test iterations. Another useful feature of Spock during parameterizing test is its ability to "unroll" each parameterized test. Feature method from previous example could be defined as (the body stays the same, so I do not repeat it):
@Unroll("should validate email #email")
def "should perform validation of email addresses"() {
    // ...
}
With that annotation, Spock generate few methods each with its own name and run them separately. We can use symbols from where blocks in @Unroll argument by preceding it with '#' sign what is a signal to Spock to use it in generated method name.

What next?

 
Well, that was just quick and short journey  through Spock and its capabilities. However, with that basic tutorial you are ready to write many unit tests. In one of my future posts I am going to describe more features of Spock focusing especially on its mocking abilities.

Integration tests with Maven and JUnit

There is no doubt that integration tests phase is crucial in modern applications development. We need to test behaviour of our subsystems and how they interact with other modules. Using JUnit and Maven it's quite easy to create integration tests and run them in separate phase than unit test. It is very important, because integration tests tend to take much more time than unit ones because they work with database, network connections, other subsystems etc. Therefore, we want to run them more rarely. With JUnit in version >= 4.8 there are two approaches for creating and running integration test:
  • using naming conventions and specifying separate executions for maven-surefire plugin
  • create marking interface and mark integration tests with @Category annotation and run test from failsafe-plugin (although it is possible to use surefire in both cases)
 

Separate executions

First method needs naming convention like naming all unit tests with "..Test.java" postfix (or "..Spec.groovy" ;) and integration tests with "..IntegrationTest.java". Then we need to change maven surefire configuration:
<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-surefire-plugin</artifactId>
    <version>2.15</version>
    <configuration>
        <skip>true</skip>    
    </configuration>
</plugin>
What I did here is forcing maven to skip default test phase. Instead of that, I will configure two separate executions (just below the <configuration> section):
<executions>
    <execution>
        <id>unit-tests</id>
        <phase>test</phase>
        <goals>
            <goal>test</goal>
        </goals>
        <configuration>
            <skip>false</skip>
            <includes>
                <include>**/*Test.class</include>
                <include>**/*Spec.class</include>
            </includes>
            <excludes>
                <exclude>**/*IntegrationTest.class</exclude>
            </excludes>
        </configuration>
    </execution>
    <execution>
        <id>integration-tests</id>
        <phase>integration-test</phase>
        <goals>
            <goal>test</goal>
        </goals>
        <configuration>
            <skip>false</skip>
            <includes>
                <include>**/*IntegrationTest.class</include>
            </includes>
        </configuration>
    </execution>
</executions>
In unit test execution I include all test that match naming convention for unit tests (both JUnit and spock ones) and exclude files matching integration test pattern and in integration test execution I did something opposite ;)

Annotations

Another method requires defining of marking interface like this:
package info.rnowak.webtex.common.test;

public interface IntegrationTest {

}
Then we can mark our integration test class with:
@Category(IntegrationTest.class)
Next thing is changing of surefire plugin configuration to omit integration test:
<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-surefire-plugin</artifactId>
    <version>2.15</version>
    <configuration>
        <includes>
            <include>**/*Test.class</include>
            <include>**/*Spec.class</include>
        </includes>  
        <excludedGroups>info.rnowak.webtex.common.test.IntegrationTest</excludedGroups> 
    </configuration>
</plugin>
What has changed here is new <excludedGroups> tag with name of interface which marks our integration tests. Next, we need to add and configure maven-failsafe plugin in order to run test from out integration test group:
<plugin><plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-failsafe-plugin</artifactId>
    <version>2.15</version>
    <executions>
        <execution>
            <goals>
                <goal>integration-test</goal>
            </goals>
            <configuration>
                <groups>info.rnowak.webtex.common.test.IntegrationTest</groups>
                <includes>
                    <include>**/*.class</include>
                </includes>
            </configuration>
        </execution>
    </executions>
</plugin>
With this configuration failsafe will run only test marked with @Category(IntegrationTest.class) annotation, no matter what their names are.

What is better?

Well, in my opinion it's just a matter of taste and style. Annotating each integration class may be a little cumbersome but we are not limited to naming classes within specified convention. On the other hand, unit test and integration test usually are named with some convention, so annotations are not a big deal.

How to use mocks in controller tests

Even since I started to write tests for my Grails application I couldn't find many articles on using mocks. Everyone is talking about tests and TDD but if you search for it there isn't many articles.

Today I want to share with you a test with mocks for a simple and complete scenario. I have a simple application that can fetch Twitter tweets and present it to user. I use REST service and I use GET to fetch tweets by id like this: http://api.twitter.com/1/statuses/show/236024636775735296.json. You can copy and paste it into your browser to see a result.

My application uses Grails 2.1 with spock-0.6 for tests. I have TwitterReaderService that fetches tweets by id, then I parse a response into my Tweet class.

TwitterController plays main part here. Users call show action along with id of a tweet. This action is my subject under test. I've implemented some basic functionality. It's easier to focus on it while writing tests.

Let's start writing a test from scratch. Most important thing here is that I use mock for my TwitterReaderService. I do not construct new TwitterReaderService(), because in this test I test only TwitterController. I am not interested in injected service. I know how this service is supposed to work and I am not interested in internals. So before every test I inject a twitterReaderServiceMock into controller:

Now it's time to think what scenarios I need to test. This line from TwitterReaderService is the most important:

You must think of this method like a black box right now. You know nothing of internals from controller's point of view. You're only interested what can be returned for you:

  • a TwitterError can be thrown
  • null can be returned
  • Tweet instance can be returned

This list is your test blueprint. Now answer a simple question for each element: "What do I want my controller to do in this situation?" and you have plan test:

  • show action should redirect to index if TwitterError is thrown and inform about error
  • show action should redirect to index and inform if tweet is not found
  • show action should show found tweet

That was easy and straightforward! And now is the best part: we use twitterReaderServiceMock to mock each of these three scenarios!

In Spock there is a good documentation about interaction with mocks. You declare what methods are called, how many times, what parameters are given and what should be returned. Remember a black box? Mock is your black box with detailed instruction, e.g.: I expect you that if receive exactly one call to readTweet with parameter '1' then you should throw me a TwitterError. Rephrase this sentence out loud and look at this:

This is a valid interaction definition on mock! It's that easy! Here is a complete test that fails for now:

You may notice 0 * _._ notation. It says: I don't want any other mocks or any other methods called. Fail this test if something is called! It's a good practice to ensure that there are no more interactions than you want.

Ok, now I need to implement controller logic to handle TwitterError.

My tests passes! We have two scenarios left. Rule stays the same: TwitterReaderService returns something and we test against it. So this line is the heart of each test, change only returned values after >>:

Here is a complete test for three scenarios and controller that passes it.

The most important thing here is that we've tested controller-service interaction without logic implementation in service! That's why mock technique is so useful. It decouples your dependencies and let you focus on exactly one subject under test. Happy testing!

A Mockito catch

Suppose we have such classes and interfaces

public class AddOrganizationAction implements Action {}
public class AddPersonToOrganizationAction implements Action {}


public interface DispatchAsync {
     void execute( Action action, AsyncCallback callback );
}


We're using the best mocking framework ;) Suppose we want to verify that code under test will call execute() with proper Action - AddOrganizationAction.
I found that many developers (including me!) check such condition with

verify(async).execute(any(AddOrganizationAction.class), any(AsyncCallback.class));

In such case AsyncCallback is not important for us. We just want to ensure that AddOrganizationAction will be passed. We run test and it's green. But suddenly if we put the code below into test it will be green too!

verify(async).execute(any(AddPersonToOrganizationAction .class), any(AsyncCallback.class));

Why? Because any() matcher doesn't check the instance of passed object to be equal to declared class (AddOrganizationAction in this case). Any() checks if passed object conforms to method signature. In this case any Action's child will do. And we have an erroneous test!
The proper matcher we'd like to use is isA() matcher that checks if passed object is instance of declared class (which means instance of class or it's children).

So the proper test should contain

verify(async).execute(isA(AddOrganizationAction.class), any(AsyncCallback.class));

Go now and search for any() usages and think about changing it to isA(). In 1 of 10 cases whenever I change all tests in a testcase to isA() usage, I find an error in implementation of logic under test. Luckily I know the catch and now you do :)

Ok. It's not really a catch but ignorance of all us developers that we don't read entire documentantation :)

Using Eclipse snippets for faster JUnit test creation (with Mockito!)

I'm using this snippet to create a template of new unit test method supporting BDD mockito tests. This is a good example for adding static imports to a class from snippets.
@${testType:newType(org.junit.Test)}
public void should${testname}() {
${staticImport:importStatic('org.mockito.BDDMockito.*', 'org.mockito.Matchers.*', 'org.mockito.Mockito.*', 'org.junit.Assert.*')}// given
// when ${cursor} // then } The result is astonishing ;)
import static org.mockito.BDDMockito.*;
import static org.mockito.Matchers.*;
import static org.mockito.Mockito.*;
import static org.junit.Assert.*;
(...) @Test public void shouldTestSomething() { // given // when CURSOR_LANDS_HERE // then }