Spock – Team Blog

Groovy, Callable and ExecutorService

Suppose you want submit job to ExecutorService.

The Baroque version

You could create a class that implements Callable:

class MyJob implements Callable<Integer> {
    @Override
    Integer call() throws Exception {
        return 42
    }
}

and give it to the executor service:

def 'submit callable as MyJob object'() {
    expect:
        executorService.submit(new MyJob()).get() == 42
}

The response is, as expected, 42.

Map as Callable version

You want to use this job only in one place so why not inline this class:

def 'submit callable as map'() {
    expect:
        executorService.submit([call: { 42 }] as Callable).get() == 42
}

The response is again 42.

Groovy closure version

Why not use closure instead of map?

def 'submit callable as closure'(){
    expect:
        executorService.submit { 42 }.get() == 42
}

The response is ... null.

Condition not satisfied:
executorService.submit { 42 }.get() == 42
|               |             |     |
|               |             null  false
|               java.util.concurrent.FutureTask@21de60b4
java.util.concurrent.Executors$FinalizableDelegatedExecutorService@1700915

Why? It is because Groovy treats this closure as Runnable, not Callable and Future#get returns null when task is complete.

Groovy closure version with cast

We have to cast our closure before submiting to executor service:

def 'submit callable as closure with cast'() {
    when:
        int result = executorService.submit({ return 42 } as Callable<Integer>).get()
    then:
        result == 42
}

The response is, as expected, again 42.

What interesting, the same test with inlined result variable fails... Strange... It could be Spock framework error.

Source code is available here.

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.

Spock, Java and Maven

Few months ago I've came across Groovy - powerful language for JVM platform which combines the power of Java with abilities typical for scripting languages (dynamic typing, metaprogramming).

Together with Groovy I've discovered spock framework (https://code.google.com/p/spock/) - specification framework for Groovy (of course you can test Java classes too!). But spock is not only test/specification framework - it also contains powerful mocking tools.

Even though spock is dedicated for Groovy there is no problem with using it for Java classes tests. In this post I'm going to describe how to configure Maven project to build and run spock specifications together with traditional JUnit tests.

Firstly, we need to prepare pom.xml and add necessary dependencies and plugins.

Two obligatory libraries are:

<dependency>
    <groupid>org.spockframework</groupId>
    <artifactid>spock-core</artifactId>
    <version>0.7-groovy-2.0</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupid>org.codehaus.groovy</groupId>
    <artifactid>groovy-all</artifactId>
    <version>${groovy.version}</version>
    <scope>test</scope>
</dependency>

Where groovy.version is property defined in pom.xml for more convenient use and easy version change, just like this:

<properties>
    <gmaven-plugin.version>1.4</gmaven-plugin.version>
    <groovy.version>2.1.5</groovy.version>
</properties>

I've added property for gmaven-plugin version for the same reason ;)

Besides these two dependencies, we can use few additional ones providing extra functionality:

cglib - for class mocking
objenesis - enables mocking classes without default constructor

To add them to the project put these lines in <dependencies> section of pom.xml:

<dependency>
    <groupid>cglib</groupId>
    <artifactid>cglib-nodep</artifactId>
    <version>3.0</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupid>org.objenesis</groupId>
    <artifactid>objenesis</artifactId>
    <version>1.3</version>
    <scope>test</scope>
</dependency>

And that's all for dependencies section. Now we will focus on plugins necessary to compile Groovy classes. We need to add gmaven-plugin with gmaven-runtime-2.0 dependency in plugins section:

<plugin>
    <groupid>org.codehaus.gmaven</groupId>
    <artifactid>gmaven-plugin</artifactId>
    <version>${gmaven-plugin.version}</version>
    <configuration>
        <providerselection>2.0</providerSelection>
    </configuration>
    <executions>
        <execution>
            <goals>
                <goal>compile</goal>
                <goal>testCompile</goal>
            </goals>
        </execution>
    </executions>
    <dependencies>
        <dependency>
            <groupid>org.codehaus.gmaven.runtime</groupId>
            <artifactid>gmaven-runtime-2.0</artifactId>
            <version>${gmaven-plugin.version}</version>
            <exclusions>
                <exclusion>
                    <groupid>org.codehaus.groovy</groupId>
                    <artifactid>groovy-all</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupid>org.codehaus.groovy</groupId>
            <artifactid>groovy-all</artifactId>
            <version>${groovy.version}</version>
        </dependency>
    </dependencies>
</plugin>

With these configuration we can use spock and write our first specifications. But there is one issue: default settings for maven-surefire plugin demand that test classes must end with "..Test" postfix, which is ok when we want to use such naming scheme for our spock tests. But if we want to name them like CommentSpec.groovy or whatever with "..Spec" ending (what in my opinion is much more readable) we need to make little change in surefire plugin configuration:

<plugin>
    <groupid>org.apache.maven.plugins</groupId>
    <artifactid>maven-surefire-plugin</artifactId>
    <version>2.15</version>
    <configuration>
        <includes>
            <include>**/*Test.java</include>
            <include>**/*Spec.java</include>
        </includes>
    </configuration>
</plugin>

As you can see there is a little trick ;) We add include directive for standard Java JUnit test ending with "..Test" postfix, but there is also an entry for spock test ending with "..Spec". And there is a trick: we must write "**/*Spec.java", not "**/*Spec.groovy", otherwise Maven will not run spock tests (which is strange and I've spent some time to figure out why Maven can't run my specs). Little update: instead of "*.java" postfix for both types of tests we can write "*.class" what is in my opinion more readable and clean:

<include>**/*Test.class</include>
<include>**/*Spec.class</include>

(thanks to Tomek Pęksa for pointing this out!)

With such configuration, we can write either traditional JUnit test and put them in src/test/java directory or groovy spock specifications and place them in src/test/groovy. And both will work together just fine :) In one of my next posts I'll write something about using spock and its mocking abilities in practice, so stay in tune.

How to keep session in HttpBuilder with cookies

In my real-world scenario I have a REST service for AJAX purposes. It renders data series for graphs. I want to test it with groovy's excellent HttpBuilder. There is a problem though - these requests are only available for already logged in users.

In this post I present a complete solution to maintain a session state between HttpBuilder's requests.

Session in HttpBuilder

First of all a quick reminder about session. Session is a simulation of state for HTTP requests, which are stateless by its nature. Once you log in you receive a unique cookie (one or more) that identifies you for sequential requests. Every time you send request you send this cookie along. This way server recognizes you and matches you to your session, which is kept on server. Cookie gets invlid once you log out or it times out, for example after 20 minutes of inactivity. Next time you visit a page you get a new, unique cookie.

In order to keep session alive in HttpBuilder I need to:

log in to my Grails application
receive a JSESSIONID cookie in response
store that cookie and send it along with every subsenquential request

I've created RestConnector class that wraps up HttpBuilder. It's main improvement is that it keeps received cookie in a list.

package eu.spoonman.connectors.RestConnector

import groovyx.net.http.Method
import groovyx.net.http.ContentType
import groovyx.net.http.HTTPBuilder
import groovyx.net.http.HttpResponseDecorator

class RestConnector {
    private String baseUrl
    private HTTPBuilder httpBuilder
    private List<String> cookies

    RestConnector(String url) {
        this.baseUrl = url
        this.httpBuilder = initializeHttpBuilder()
        this.cookies = []
    }

    public def request(Method method, ContentType contentType, String url, Map<String, Serializable> params) {
        debug("Send $method request to ${this.baseUrl}$url: $params")
        httpBuilder.request(method, contentType) { request ->
            uri.path = url
            uri.query = params
            headers['Cookie'] = cookies.join(';')
        }
    }

    private HTTPBuilder initializeHttpBuilder() {
        def httpBuilder = new HTTPBuilder(baseUrl)

        httpBuilder.handler.success = { HttpResponseDecorator resp, reader ->
            resp.getHeaders('Set-Cookie').each {
                //[Set-Cookie: JSESSIONID=E68D4799D4D6282F0348FDB7E8B88AE9; Path=/frontoffice/; HttpOnly]
                String cookie = it.value.split(';')[0]
                debug("Adding cookie to collection: $cookie")
                cookies.add(cookie)
            }
            debug("Response: ${reader}")
            return reader
        }
        return httpBuilder
    }


    private debug(String message) {
        System.out.println(message) //for Gradle
    }
}

A few things to notice in a class above. Constructor sets base URL and creates HttpBuilder instance that can be reused. Next, there is a handler on successful request that checks if I receive any cookie. It adds received cookies to list. Finally, there is a request method that calls HttpBuilder#request but it adds cookies to HTTP headers so server can recognize me as a logged in user.

Sending cookies with every request is a core component in here. It simulates browser's behavior and maintains session.

How to use it?

I will show you how to use this utility class it in Spock test below. It is fairly simple.

First I login to my application and I ensure that I receive a cookie in return, which is equivalent to being logged in. Then I send a request with that cookie sent in HTTP header. This is a Spock test that implements it:

package eu.spoonman.specs.rest

import eu.spoonman.connectors.RestConnector.RestConnector
import groovyx.net.http.ContentType
import groovyx.net.http.Method
import spock.lang.Shared
import spock.lang.Specification
import spock.lang.Stepwise

@Stepwise
class RestChartSpec extends Specification {
    @Shared
    RestConnector restConnector

    def setupSpec() {
        restConnector = new RestConnector('http://localhost:8080')
    }

    def "should login as test"() {
        given:
            Map params = [j_username: 'test', j_password: 'test']
        when:
            restConnector.request(Method.POST, ContentType.ANY, '/frontoffice/j_spring_security_check', params)
        then:
            !(restConnector.cookies.empty)
    }

    def "should allow access to chart data series"() {
        given:
            Map params = [days: 14]
        when:
            Map result = restConnector.request(Method.POST, ContentType.JSON, "frontoffice/chart/series", params)
        then:
            result != null
            result.series.size() > 0
    }
}

I create a new RestConnector instance in setupSpec with my application's base URL. Please notice that it has @Shared annotation so it's shared between tests.

@Stepwise is crucial annotation for this specification. It means that Spock executes tests exactly in order they're defined. I need to ensure that login is executed first. I also need to assert that I receive a cookie and list is not empty. I could move this step into setupSpec method too, but I prefer it to be a first test in a specification.

Second test is always executed after login thus it sends cookies within request headers. This is exactly what I wanted to achieve.