DDevelopment & Design

Thought static method can’t be easy to mock, stub nor track? Wrong!

No matter why, no matter is it a good idea. Sometimes one just wants to check or it’s necessary to be done. Mock a static method, woot? Impossibru! In pure Java world it is still a struggle. But Groovy allows you to do that really simple. Well, not groovy alone, but with a great support of Spock. Lets move on straight to the example. To catch some context we have an abstract for the example needs. A marketing project with a set of offers. One to many. import spock.lang.Specification class OfferFacadeSpec extends Specification { OfferFacade facade = new OfferFacade() def setup() { GroovyMock(Project, global: true) } def 'delegates an add offer call to the domain with proper params'() { given: Map params = [projId: projectId, name: offerName] when: Offer returnedOffer = facade.add(params) then: 1 * Project.addOffer(projectId, _) >> { projId, offer -> offer } returnedOffer.name == params.name where: projectId | offerName 1 | 'an Offer' 15 | 'whasup!?' 123 | 'doskonała oferta - kup teraz!' } } So we test a facade responsible for handling “add offer to the project” call triggered  somewhere in a GUI. We want to ensure that static method Project.addOffer(long, Offer) will receive correct params when java.util.Map with user form input comes to the facade.add(params). This is unit test, so how Project.addOffer() works is out of scope. Thus we want to stub it. The most important is a GroovyMock(Project, global: true) statement. What it does is modifing Project class to behave like a Spock’s mock. GroovyMock() itself is a method inherited from Specification.  The global flag is necessary to enable mocking static methods. However when one comes to the need of mocking static method, author of Spock Framework advice to consider redesigning of implementation. It’s not a bad advice, I must say. Another important thing are assertions at then: block. First one checks an interaction, if the Project.addOffer() method was called exactly once, with a 1st argument equal to the projectId and some other param (we don’t have an object instance yet to assert anything about it). Right shit operator leads us to the stub which replaces original method implementation by such statement. As a good stub it does nothing. The original method definition has return type Offer. The stub needs to do the same. So an offer passed as the 2nd argument is just returned. Thanks to this we can assert about name property if it’s equal with the value from params. If no return was designed the name could be checked inside the stub Closure, prefixed with an assert keyword. Worth of  mentioning is that if you want to track interactions of original static method implementation without replacing it, then you should try using GroovySpy instead of GroovyMock. Unfortunately static methods declared at Java object can’t be treated in such ways. Though regular mocks and whole goodness of Spock can be used to test pure Java code, which is awesome anyway :)No matter why, no matter is it a good idea. Sometimes one just wants to check or it’s necessary to be done. Mock a static method, woot? Impossibru! In pure Java world it is still a struggle. But Groovy allows you to do that really simple. Well, not groovy alone, but with a great support of Spock. Lets move on straight to the example. To catch some context we have an abstract for the example needs. A marketing project with a set of offers. One to many. import spock.lang.Specification class OfferFacadeSpec extends Specification { OfferFacade facade = new OfferFacade() def setup() { GroovyMock(Project, global: true) } def 'delegates an add offer call to the domain with proper params'() { given: Map params = [projId: projectId, name: offerName] when: Offer returnedOffer = facade.add(params) then: 1 * Project.addOffer(projectId, _) >> { projId, offer -> offer } returnedOffer.name == params.name where: projectId | offerName 1 | 'an Offer' 15 | 'whasup!?' 123 | 'doskonała oferta - kup teraz!' } } So we test a facade responsible for handling “add offer to the project” call triggered  somewhere in a GUI. We want to ensure that static method Project.addOffer(long, Offer) will receive correct params when java.util.Map with user form input comes to the facade.add(params). This is unit test, so how Project.addOffer() works is out of scope. Thus we want to stub it. The most important is a GroovyMock(Project, global: true) statement. What it does is modifing Project class to behave like a Spock’s mock. GroovyMock() itself is a method inherited from Specification.  The global flag is necessary to enable mocking static methods. However when one comes to the need of mocking static method, author of Spock Framework advice to consider redesigning of implementation. It’s not a bad advice, I must say. Another important thing are assertions at then: block. First one checks an interaction, if the Project.addOffer() method was called exactly once, with a 1st argument equal to the projectId and some other param (we don’t have an object instance yet to assert anything about it). Right shit operator leads us to the stub which replaces original method implementation by such statement. As a good stub it does nothing. The original method definition has return type Offer. The stub needs to do the same. So an offer passed as the 2nd argument is just returned. Thanks to this we can assert about name property if it’s equal with the value from params. If no return was designed the name could be checked inside the stub Closure, prefixed with an assert keyword. Worth of  mentioning is that if you want to track interactions of original static method implementation without replacing it, then you should try using GroovySpy instead of GroovyMock. Unfortunately static methods declared at Java object can’t be treated in such ways. Though regular mocks and whole goodness of Spock can be used to test pure Java code, which is awesome anyway :)

No matter why, no matter is it a good idea. Sometimes one just wants to check or it’s necessary to be done. Mock a static method, woot? Impossibru!

In pure Java world it is still a struggle. But Groovy allows you to do that really simple. Well, not groovy alone, but with a great support of Spock.

Lets move on straight to the example. To catch some context we have an abstract for the example needs. A marketing project with a set of offers. One to many.

pipeline {
  agent any
  stages {
    stage('Unit Test') {
      steps {
        sh 'mvn clean test'
      }
    }
    stage('Deploy Standalone') {
      steps {
        sh 'mvn deploy -P standalone'
      }
    }
    stage('Deploy AnyPoint') {
      environment {
        ANYPOINT_CREDENTIALS = credentials('anypoint.credentials')
      }
      steps {
        sh 'mvn deploy -P arm -Darm.target.name=local-4.0.0-ee -Danypoint.username=${ANYPOINT_CREDENTIALS_USR}  -Danypoint.password=${ANYPOINT_CREDENTIALS_PSW}'
      }
    }
    stage('Deploy CloudHub') {
      environment {
        ANYPOINT_CREDENTIALS = credentials('anypoint.credentials')
      }
      steps {
        sh 'mvn deploy -P cloudhub -Dmule.version=4.0.0 -Danypoint.username=${ANYPOINT_CREDENTIALS_USR} -Danypoint.password=${ANYPOINT_CREDENTIALS_PSW}'
      }
    }
  }
}

 

So we test a

facade responsible for handling “add offer to the project” call triggered  somewhere in a GUI.
We want to ensure that static method Project.addOffer(long, Offer) will receive correct params when java.util.Map with user form input comes to the facade.add(params).
This is unit test, so how Project.addOffer() works is out of scope. Thus we want to stub it.

The most important is a GroovyMock(Project, global: true) statement.
What it does is modifing Project class to behave like a Spock’s mock.
GroovyMock() itself is a method inherited from Specification.  *The global flag is necessary to enable mocking static methods.*
However when one comes to the need of mocking static method, author of Spock Framework advice to consider redesigning of implementation. It’s not a bad advice, I must say.

Another important thing are assertions at then: block. First one checks an interaction, if the Project.addOffer() method was called exactly once, with a 1st argument equal to the projectId and some other param (we don’t have an object instance yet to assert anything about it).
Right shit operator leads us to the stub which replaces original method implementation by such statement.
As a good stub it does nothing. The original method definition has return type Offer. The stub needs to do the same. So an offer passed as the 2nd argument is just returned.
Thanks to this we can assert about name property if it’s equal with the value from params. If no return was designed the name could be checked inside the stub Closure, prefixed with an assert keyword.

Worth of  mentioning is that if you want to track interactions of original static method implementation without replacing it, then you should try using GroovySpy instead of GroovyMock.

Unfortunately static methods declared at Java object can’t be treated in such ways. Though regular mocks and whole goodness of Spock can be used to test pure Java code, which is awesome anyway :)

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DDevelopment & Design

Using WsLite in practice

TL;DR

There is a example working GitHub project which covers unit testing and request/response logging when using WsLite.

Why Groovy WsLite ?

I’m a huge fan of Groovy WsLite project for calling SOAP web services. Yes, in a real world you have to deal with those - big companies have huge amount of “legacy” code and are crazy about homogeneous architecture - only SOAP, Java, Oracle, AIX…

But I also never been comfortable with XFire/CXF approach of web service client code generation. I wrote a bit about other posibilites in this post. With JAXB you can also experience some freaky classloading errors - as Tomek described on his blog. In a large commercial project the “the less code the better” principle is significant. And the code generated from XSD could look kinda ugly - especially more complicated structures like sequences, choices, anys etc.

Using WsLite with native Groovy concepts like XmlSlurper could be a great choice. But since it’s a dynamic approach you have to be really careful - write good unit tests and log requests. Below are my few hints for using WsLite in practice.

Unit testing

Suppose you have some invocation of WsLite SOAPClient (original WsLite example):

def getMothersDay(long _year) {
    def response = client.send(SOAPAction: action) {
       body {
           GetMothersDay('xmlns':'http://www.27seconds.com/Holidays/US/Dates/') {
              year(_year)
           }
       }
    }
    response.GetMothersDayResponse.GetMothersDayResult.text()
}

How can the unit test like? My suggestion is to mock SOAPClient and write a simple helper to test that builded XML is correct. Example using great SpockFramework: 

void setup() {
   client = Mock(SOAPClient)
   service.client = client
}

def "should pass year to GetMothersDay and return date"() {
  given:
      def year = 2013
  when:
      def date = service.getMothersDay(year)
  then:
      1 * client.send(_, _) >> { Map params, Closure requestBuilder ->
            Document doc = buildAndParseXml(requestBuilder)
            assertXpathEvaluatesTo("$year", '//ns:GetMothersDay/ns:year', doc)
            return mockResponse(Responses.mothersDay)
      }
      date == "2013-05-12T00:00:00"
}

This uses a real cool feature of Spock - even when you mock the invocation with “any mark” (_), you are able to get actual arguments. So we can build XML that would be passed to SOAPClient's send method and check that specific XPaths are correct:

void setup() {
    engine = XMLUnit.newXpathEngine()
    engine.setNamespaceContext(new SimpleNamespaceContext(namespaces()))
}

protected Document buildAndParseXml(Closure xmlBuilder) {
    def writer = new StringWriter()
    def builder = new MarkupBuilder(writer)
    builder.xml(xmlBuilder)
    return XMLUnit.buildControlDocument(writer.toString())
}

protected void assertXpathEvaluatesTo(String expectedValue,
                                      String xpathExpression, Document doc) throws XpathException {
    Assert.assertEquals(expectedValue,
            engine.evaluate(xpathExpression, doc))
}

protected Map namespaces() {
    return [ns: 'http://www.27seconds.com/Holidays/US/Dates/']
}

The XMLUnit library is used just for XpathEngine, but it is much more powerful for comparing XML documents. The NamespaceContext is needed to use correct prefixes (e.g. ns:GetMothersDay) in your Xpath expressions.

Finally - the mock returns SOAPResponse instance filled with envelope parsed from some constant XML:

protected SOAPResponse mockResponse(String resp) {
    def envelope = new XmlSlurper().parseText(resp)
    new SOAPResponse(envelope: envelope)
}

Request and response logging

The WsLite itself doesn’t use any logging framework. We usually handle it by adding own sendWithLogging method:

private SOAPResponse sendWithLogging(String action, Closure cl) {
    SOAPResponse response = client.send(SOAPAction: action, cl)
    log(response?.httpRequest, response?.httpResponse)
    return response
}

private void log(HTTPRequest request, HTTPResponse response) {
    log.debug("HTTPRequest $request with content:\n${request?.contentAsString}")
    log.debug("HTTPResponse $response with content:\n${response?.contentAsString}")
}

This logs the actual request and response send through SOAPClient. But it logs only when invocation is successful and errors are much more interesting… So here goes withExceptionHandler method:

private SOAPResponse withExceptionHandler(Closure cl) {
    try {
        cl.call()
    } catch (SOAPFaultException soapEx) {
        log(soapEx.httpRequest, soapEx.httpResponse)
        def message = soapEx.hasFault() ? soapEx.fault.text() : soapEx.message
        throw new InfrastructureException(message)
    } catch (HTTPClientException httpEx) {
        log(httpEx.request, httpEx.response)
        throw new InfrastructureException(httpEx.message)
    }
}
def send(String action, Closure cl) {
    withExceptionHandler {
        sendWithLogging(action, cl)
    }
}

XmlSlurper gotchas

Working with XML document with XmlSlurper is generally great fun, but is some cases could introduce some problems. A trivial example is parsing an id with a number to Long value:

def id = Long.valueOf(edit.'@id' as String)

The Attribute class (which edit.'@id' evaluates to) can be converted to String using as operator, but converting to Long requires using valueOf.

The second example is a bit more complicated. Consider following XML fragment:

<edit id="3">
   <params>
      <param value="label1" name="label"/>
      <param value="2" name="param2"/>
   </params>
   <value>123</value>
</edit>
<edit id="6">
   <params>
      <param value="label2" name="label"/>
      <param value="2" name="param2"/>
   </params>
   <value>456</value>
</edit>

We want to find id of edit whose label is label1. The simplest solution seems to be:

def param = doc.edit.params.param.find { it['@value'] == 'label1' }
def edit = params.parent().parent()

But it doesn’t work! The parent method returns multiple edits, not only the one that is parent of given param…

Here’s the correct solution:

doc.edit.find { edit ->
    edit.params.param.find { it['@value'] == 'label1' }
}

Example

The example working project covering those hints could be found on GitHub.