Archive for the ‘Tools’ Category

Stubbing methods returning java.util.Optional with Spock is more tricky that you would probably expect. Get know how to do it efficiently.

by Infrogmation, Wikimedia Commons, public domain

Introduction

One of the nice features of the mocking framework in Spock is an ability to return sensible default values for unstubbed method calls made on stubs. Empty list for a method returning List, 0 for long, etc. Very handy if you don’t care about returned value in a particular test, but for example would like to prevent NullPointerException later in the flow. Unfortunately Spock 1.0 and 1.1-rc-2 (still compatible with Java 6) is completely not aware of types added in Java 8 (such as Optional or CompletableFutures). You may say “no problem” null is acceptable in many cases, but with Optional the situation is even worst.

Issue

Imaging the following code – method returning Optional and a try to use it in a test:

interface Repository<T> {
    Optional<T> getMaybeById(long id)
}

@Ignore("Broken")
def "should not fail on unstubbed call with Optional return type"() {
    given:
        Dao<Order> dao = Stub()
    when:
        dao.getMaybeById(5)
    then:
        noExceptionThrown()
}

You may think – null will be returned on the getMaybeById() call, but it’s not.

Expected no exception to be thrown, but got 'org.spockframework.mock.CannotCreateMockException'

    at spock.lang.Specification.noExceptionThrown(Specification.java:119)
    at info.solidsoft.blog.spock10.other.CustomDefaultResponseSpec.should not fail on unstubbed call with Optional return type(CustomDefaultResponseSpec.groovy:19)
Caused by: org.spockframework.mock.CannotCreateMockException: Cannot create mock for class java.util.Optional because Java mocks cannot mock final classes. If the code under test is written in Groovy, use a Groovy mock.
    at org.spockframework.mock.runtime.JavaMockFactory.createInternal(JavaMockFactory.java:49)
    at org.spockframework.mock.runtime.JavaMockFactory.create(JavaMockFactory.java:40)
(...)

The test fails at runtime as Spock is not able to stub java.util.Optional which is a final class:

CannotCreateMockException: Cannot create mock for class java.util.Optional
    because Java mocks cannot mock final classes.

What we can do?

Two workarounds

The EmptyOrDummyResponse factory class (which tries to be smart) is used by default for stubs when an ustubbed method is being called. However, it can be changed on demand during a stub creation:

def "should not fail on unstubbed call with Optional return type - workaround 1"() {
    given:
        Dao<Order> dao = Stub([defaultResponse: ZeroOrNullResponse.INSTANCE])
    when:
        dao.getMaybeById(5)
    then:
        noExceptionThrown()
}

This test will pass (getMaybeById() just returned null), but there is an easiest way to achieve the same result.

Spock uses EmptyOrDummyResponse only for stubs (created with a Stub() method). For mocks (created with a Mock() method) the ZeroOrNullResponse factory is used (which makes sense as mocks should focus on interaction verification not just stubbing). Thanks to that a smart logic trying to return sensible default value is disabled in much simpler way:

def "should not fail on unstubbed call with Optional return type - workaround 2"() {
    given:
        Dao<Order> dao = Mock()
    when:
        dao.getMaybeById(5)
    then:
        noExceptionThrown()
}

However, this workaround is far from being perfect. Firstly, your colleagues may be surprised why a mock is created while only stubbing is performed (by the way, both stubbing and verifying interaction on the same mock is tricky itself in Spock, but this is a topic for an another blog post). Secondly, wouldn’t it be nice to have an empty optional (instead of null) returned by default?

Solution

In addition to an aforementioned way to use predefined factories for default return types Spock provides an ability to write a custom one. Let’s create EmptyOrDummyResponse-life factory which is aware of Java 8 types. In fact, the implementation is very straightforward:

class Java8EmptyOrDummyResponse implements IDefaultResponse {

    public static final Java8EmptyOrDummyResponse INSTANCE = new Java8EmptyOrDummyResponse()

    private Java8EmptyOrDummyResponse() {}

    @Override
    public Object respond(IMockInvocation invocation) {
        if (invocation.getMethod().getReturnType() == Optional) {
            return Optional.empty()
        }
        //possibly CompletableFutures.completedFuture(), dates and maybe others

        return EmptyOrDummyResponse.INSTANCE.respond(invocation)
    }
}

Our class implements an IDefaultResponse interface with one respond() method. Inside, we can apply custom logic for Optional, CompletableFutures and maybe other Java 8 specific types. As a fallback (for “standard” types) we switch to the original EmptyOrDummyResponse. This code works as expected:

@SuppressWarnings("GroovyPointlessBoolean")
def "should return empty Optional for unstubbed calls"() {
    given:
        Dao<Order> dao = Stub([defaultResponse: Java8EmptyOrDummy.INSTANCE])
    when:
        Optional<Order> result = dao.getMaybeById(5)
    then:
        result?.isPresent() == false    //NOT the same as !result?.isPresent()
}

Please pay attention to consider Groovy truth implementation while making assertions with Optional. !result?.isPresent() would be fulfilled also for null returned from a method.

However, maybe it would be good to simplify a Java 8 aware stub creation a little bit? To do that an extra method can be created:

private <T> T Stub8(Class<T> clazz) {
    return Stub([defaultResponse: Java8EmptyOrDummy.INSTANCE], clazz)
}

@SuppressWarnings("GroovyPointlessBoolean")
def "should return empty Optional for unstubbed calls with Stub8"() {
    given:
        Dao<Order> dao = Stub8(Dao)
    when:
        Optional<Order> result = dao.getMaybeById(5)
    then:
        result?.isPresent() == false    //NOT the same as !result?.isPresent()
}

Unfortunately in in that case an enhanced more compact stub creation syntax available in Spock 1.1 cannot be used with our Stub8() method. All because Spock will not be able to determine it’s type looking on he left side on assignment. In the end, however, it is much shorter than setting defaultResponse in an every stub creation.

Please note that due to Spock limitations that method cannot be put in a trait (or a separate class) and has to be defined in the current test or a custom base (super) class for all the tests (extending itself spock.lang.Specification), e.g.:

abstract class Java8AwareSpecification extends Specification {
    protected <T> T Stub8(Class<T> clazz) { ... }
}

class MyFancyTest extends Java8AwareSpecification { ... }

Summary

Thanks to exploring some Spock internals related to a stub and mock creation it was possible to enhance default strategy for smart responses for unstubbed calls to nicely support Java 8 features. This is just one of the topics I covered in my advanced “Interesting nooks and crannies of Spock you (may) have never seen before” presentation gave at Gr8Conf Europe 2016. You may want to see it :-).

Btw, the good news is that upcoming Spock 1.1(-rc-3) will contain native support for returning sensible default values for unstubbed Optional method calls.

Self promotion. Would you like to improve your and your team testing skills and knowledge of Spock quickly and efficiently? I conduct a condensed (unit) testing training which you may find useful.

Learn how to visualize complex input parameters in parameterized tests in the way improving the readability of the test report.

Trimmed Hedge

By Tomwsulcer – CC0, Wikipedia

Introduction

Parameterized tests can simplify the way how the same functionality can be verified with different input parameters. Spock with its where block, data tables and data pipes makes it very easy to use in a very readable way. The input parameters are nicely presented in a test execution report (in IDE, Jenkins or generated HTML). They can be formatted in a desired order and completed with a custom constant message. It usually works flawlessly for simple objects (such as numbers, booleans, enums and strings). However, in the situation where complex objects are used (e.g. bigger value objects or custom classes) the whole output can be hijacked by just one very verbose parameter:

Very long full toString

or meaningless default toString() implementation: foo.bar.Unknown@78ac1102:

Meaningless Default toString in tests

Our sample code base

To present different available approaches I will use a very simplified version of an account & invoice related domain implemented with DDD in one of the projects I worked in.

The main class here is Invoice which represents an invoice :). The object is immutable (here with Groovy AST transformation, but it could be also achieved with Project Lombok or manually) which means that methods modifying a state return a new version of this class.

@Immutable
class Invoice {

    enum Status {
        ISSUED, PAID, OVERDUE, CANCELLED
    }

    Status status
    BigDecimal issuedAmount
    BigDecimal remainingAmount
    LocalDate issueDate
    //some other fields

    //different production methods

    //production toString() with all useful business fields
}

There is also Account class with an amountToPay() method returning amount to pay based in open invoices.

Naive approach (strongly not recommended)

As the first idea one could be tempted to modify toString() method implementation to, for example, display only 2 of the 10 fields in a class. However, it is a bad idea to change production toString() just for the better output in tests. What is more, other tests or error reporting in a production system can prefer to display more information. Luckily in Spock we have two nice techniques to cope with it.

Technique 1 – an extra formatting method

Test/specification names in Spock can be enhanced with #parameterName (not with $ character used internally by Groovy which is not allowed in a method name) placed in a test name or in an @Unroll annotation. In addition there is an ability to use object property value or call a parameterless method.

class AmountToPayInvoiceAccountSpec extends Specification {

    def "paid and cancelled invoices (#invoice.formatForTest()) should be ignored in current amount to pay"() {
        given:
            Account account = AccountTestFixture.createForInvoice(invoice)
        expect:
            account.amountToPay() == 0.0
        where:
            invoice << [paidInvoice, cancelledInvoice]
    }

    (...)
}

//required modifications in production code
class Invoice {

   (...)

   String formatForTest() {
       return "$issuedAmount: $status"
   }

Test specific production method - result

It’s nice to get just two fields from an object, however, in many cases we don’t want to add an artificial formatting method to production code just to be used in tests.

A tip. Don’t forget to enable unrolling of paremterized tests to instruct Spock to create a separate (sub)test for every input parameters set. It can be done manually by placing @Unroll annotation on an every parameterized method or at the class level. Alternatively the spock-global-unroll extension can be used to turn it on automatically in the whole project.

Technique 2 – an extra input parameter

Luckily, as an alternative it is possible to define an another artificial input parameter directly in a test. It looks like a ordinarily variable, but has access to a set of input parameters (for a given iteration) and can operate on they. That extra parameter is treated by Spock equally to others (however usually there is no need to reference to it in a test code – beside a test name).

class AmountToPayInvoiceAccountSpec extends Specification {

    @Shared
    private Invoice first = createOpenForAmount(200)
    @Shared
    private Invoice second = createOpenForAmount(300)

    def "current amount to pay (#expectedToPayAmount) should ignore paid and cancelled invoices (#invoicesDesc)"() {
        given:
            Account account = AccountTestFixture.createForInvoices(invoices)
        expect:
            account.amountToPay() == expectedToPayAmount
        where:
            invoices                   || expectedToPayAmount
            [paid(first), second]      || 300.0
            [first, cancelled(second)] || 200.0
            [first, second]            || 500.0

            invoicesDesc = createInvoicesDesc(invoices)
    }

    (...)
}

Implementation note. Methods createOpenForAmount() as well as paid() and cancelled() are implemented in a test specific InvoiceTestFixture class.

The result looks very nicely:
spock-formatting-input-parameters-test-specified-result

Just from the report it is pretty visible that there is a (regression) issue with handling CANELLED invoices. The assertion error is also helpful:

spock-formatting-input-parameters-test-specified-error-message

It’s worth to notice in this place that this technique can be also mixed with data pipes (in addition to data tables):

    where:
        invoice << [paidInvoice, cancelledInvoice]
        invoiceDesc = createInvoiceDesc(invoice)

A tip. Pay attention that in opposite to regular parameters in Spock the artificial one is created with an = operator not with <<.

Summary

The aforementioned techniques can be used to improve the readability of your test execution report. It’s useful during the development, but what is even more important it becomes indispensable if Spock is used for Behavior Driven Development and reports are read by, so called, Business People (i.e. need to be worded in the specific way).

[OT] The reason to bring up this topic is a fact that recently two colleagues of mine were struggling with that issue in their tests. Unfortunately they overlooked that slide in my advanced Spock presentation at Gr8Conf EU ;). Blessing in disguise, I was in the office to support them immediately. Nevertheless, not so long ago I’ve seen a presentation by Scott Hanselman about productivity. I liked the idea that every good question is worth to be answered on a blog. Replying privately (especially via email) usually can help only just one person. Writing a blog post and sending that person a link in addition can help other people struggling with the same issue.

Self promotion. Would you like to improve your and your team testing skills and knowledge of Spock quickly and efficiently? I conduct a condensed (unit) testing training which you may find useful.

Get know how to create mocks and spies in even more compact way with Spock 1.1

Introduction

Spock heavily leverages operator overloading (and Groovy magic) to provide very compact and highly readable specifications (tests) which wouldn’t be able to achieve in Java. This is very clearly visible among others in the whole mocking framework. However, preparing my Spock training I found a place for further improvements in a way how mocks and spies are created.

Shorter and shorter pencils

The Groovy way

Probably the most common way to create mocks (and spies) among devoted Groovy & Grails users is:

def dao = Mock(Dao)

The type inference in IDE works fine (there is type aware code completion). Nonetheless, this syntax is usually less readable for Java newcomers (people using Spock to tests production code written in Java) and in general for people preferring strong typing (including me).

The Java way

The same mock creation in the Java way would look as above:

Dao dao = Mock(Dao)

The first impression about this code snipped is – very verbose. Well, it is a Java way – why should we expect anything more ;).

The shorter Java way

As I already mentioned Spock leverages Groovy magic and the following construction works perfectly fine:

Dao dao = Mock()

Under the hood Spock uses a type used in the left side of an assignment to determine a type for which a mock should be created. Nominally everything is ok. Unfortunately there is one awkward limitation:

spock-1-0-mock-warning

IDE complains about unsafe type assignment and without getting deeper into the logic used in Spock it is justified. Luckily the situation is not hopeless.

The shorter Java way – Spock 1.1

Preparing practical exercises for my Spock training some time ago gave me an excuse to get into the details of implementation and after a few minutes I was able to improve the code to make it work cleanly in IDE (after a few years of living with that limitation!).

Dao dao = Mock()

spock-1-1-mock-no-warning2

No warning in IDE anymore.

Summary

Multiple times in my career I experienced a well known truth that preparing a presentation is very educational also for the presenter. In a case of a new 3-day long training it is even more noticeable – attendees have much more time to ask you uncomfortable question :). Not for the first time my preparations resulted in a new feature or an enhancement in some popular libraries or frameworks.

The last code snippet requires Spock in version 1.1 (which as a time of writing is available as the release candidate 3 – 1.1-rc-3 to not trigger a warning in IDE. There is a lot of new features in Spock 1.1 – why wouldn’t you give it a try? :)

Picture credits: GDJ from openclipart.org

Would it be useful to unroll all parameterized Spock tests automatically?

I’ve been always frustrated with the need to add @Unroll annotation to every parameterized test/feature (or at least at the class/specification level) to make unrolling works in Spock. It was even worse to deal with the code with already missing @Unroll annotations and cryptic test results. For backward compatibility unrolling will rather not be enabled by default in the foreseeable future, but luckily there is a quick solution.

Unroll

Photo: Christopher Michel, CC BY 2.0

Unroll for all and for free

To enable global unrolling it is only required to add spock-global-unroll.jar to your classpath:

testCompile 'info.solidsoft.spock:spock-global-unroll:0.5.0'

To make it easier to use spock-global-unroll with different Spock versions (like 1.0-groovy-2.0 and 1.0-groovy-2.3) the plugin does not have the compile dependency on Spock and a proper spock-core jar has to be explicitly defined in a build configuration. E.g.:

testCompile 'info.solidsoft.spock:spock-global-unroll:0.5.0'
testCompile 'org.spockframework:spock-core:1.0-groovy-2.4'

That’s all. spock-global-unroll is a global extension which is activated automatically by Spock. All parameterized Spock tests are unrolled without the need to use @Unroll annotation.

Disabling automatic unrolling for a class

Automatic unrolling can be disabled for a particular class by putting @DisableGlobalUnroll on it.

The nice thing is that the @Unroll annotations manually placed at the test (feature) level can be used to unroll particular tests anyway (even if automatic unrolling has been disabled for given class).

@DisableGlobalUnroll
class PeselValidatorSpec extends Specification {

    //one big test for multiple input parameters
    def "should not be unrolled for some reasons PESEL #number"() { ... }

    (...)
}

Overriding default test name

To override default test name expanding (with #placeHolders in a test name) @Unroll annotation with a custom text can be used on the top of feature method or at the specification level.

@DisableGlobalUnroll
class PeselValidatorSpec extends Specification {

    //one big test for multiple input parameters
    def "should not be unrolled for some reasons PESEL #number"() { ... }

    //unrolled anyway
    @Unroll("PESEL '#pesel' should be #description")
    def "should validate PESEL correctness"() { ... }

    (...)
}

Summary

Being able to implement automatic tests unrolling within 15 minutes I decided to share it with the community – maybe there are others who don’t like to write boilerplate code :). The code written to achieve it has just a few lines of production code (of course there are also 3 test classes to verify if the extension works as expected :) ). This shows the power of Spock extensibility.

The complete source code is available from GitHub: https://github.com/szpak/spock-global-unroll

Update 20160521. I added automatic migration scripts in the project README to make a migration easier.

Btw, if you would like to find out more about “Interesting nooks and crannies of Spock” I will be speaking about them in May and June at GeeCON 2016 in Kraków, Gr8Conf 2016 in Copenhagen and Devoxx Poland again in Kraków.

Geecon big paw logo
GR8 Conf 2016 Europe
Devoxx Poland 2016 Speaker Badge

Self promotion. Would you like to improve your and your team testing skills and knowledge of Spock quickly and efficiently? I conduct condensed (unit) testing training which you may find useful.

How to simplify Mockito usage by removing static imports in Java 8 based projects.

Rationale

Mockito API is based on static methods aggregated (mostly) in the (BDD)Mockito class followed by extremely fluent, chained method calls. Mock creation, stubbing and call verification can be initiated with mock/spy/given/then/verify static methods:

@Test
public void shouldVerifyMethodExecution() {
    //given
    TacticalStation tsSpy = BDDMockito.spy(TacticalStation.class);
    BDDMockito.willDoNothing().given(tsSpy).fireTorpedo(2);
    //when
    tsSpy.fireTorpedo(2);
    tsSpy.fireTorpedo(2);
    //then
    BDDMockito.then(tsSpy).should(BDDMockito.times(2)).fireTorpedo(2);
}

Quite verbose, but starting with Java 5 one can use static imports to simplify the code, but at the cost of additional static imports:

import static org.mockito.BDDMockito.then;
import static org.mockito.BDDMockito.willDoNothing;
import static org.mockito.BDDMockito.spy;
import static org.mockito.BDDMockito.times;
(...)

@Test
public void shouldVerifyMethodExecution() {
    //given
    TacticalStation tsSpy = spy(TacticalStation.class);
    willDoNothing().given(tsSpy).fireTorpedo(2);
    //when
    tsSpy.fireTorpedo(2);
    tsSpy.fireTorpedo(2);
    //then
    then(tsSpy).should(times(2)).fireTorpedo(2);
}

Imports can be hidden in IDE and usually do not disturb much. Nevertheless to be able to write just a method name (e.g. mock(TacticalStation.class)) without a class is it required to press ALT-ENTER (in IntelliJ IDEA) to add each static import on the first usage of a given method in a test class. The situation is even worse in Eclipse where it is required to earlier add BDDMockito to “Favorites” in “Content Assist” to make it suggested by IDE. Eclipse guys could say “you have to do it just once”, but as I experienced during my testing/TDD trainings it makes a Mockito learning (usage) curve a little bit steeper.

Of course there are some tricks like using star imports by default for Mockito classes to reduce number of required key strokes, but if you use Java 8 in your project (hopefully a majority of you) there is a simpler way to cope with it.

Static imports free approach

Mockito-Java8 2.0.0 (and its counterpart for Mockito 1.10.x – version 1.0.0) introduces a set of interfaces which provide all methods from Mockito API. By “implement” them in a test class all those methods become automatically directly accessible in written tests:

//no static imports needed!

public class SpaceShipTest implements WithBDDMockito {

    @Test
    public void shouldVerifyMethodExecution() {
        //given
        TacticalStation tsSpy = spy(TacticalStation.class);
        willDoNothing().given(tsSpy).fireTorpedo(2);
        //when
        tsSpy.fireTorpedo(2);
        tsSpy.fireTorpedo(2);
        //then
        then(tsSpy).should(times(2)).fireTorpedo(2);
    }
}

The code looks exactly like in the previous snippet, but there is not need to do any static import (besides a normal import of WithBDDMockito itself).

Under the hood the WithBDDMockito interface implementation is dead simple. All methods are default methods which just delegate to proper static method in BDDMockito class.

default <T> BDDMockito.BDDMyOngoingStubbing<T> given(T methodCall) {
    return BDDMockito.given(methodCall);
}

Flavors of Mockito

Mockito methods are provided by 3 base interfaces, being an entry points for given set of methods:
WithBDDMockito – stubbing/mocking API in BDD style (provides also classic API).
WithMockito – classic stubbing/mocking API
WithAdditionalMatchers – additional Mokcito matchers (basic account are included in With(BDD)Mockito)

Summary

Java 8 has opened the new opportunities how (test) code can be written in more compact and readable way. Static imports free Mockito code can simplify writing tests a little bit, but there is more feature already available in Mockito-Java8 and even more to be included in Mockito 3.0 (those for which Mockito internals have to be modified in a non backward compatible way). Too take more ideas how code/projects can be refactored to benefit from Java 8 you can see my short presentation “Java 8 brings power to testing!” (slides and video).

Mockito-Java8 2.0.0-beta (for Mockito >=2.0.22-beta) and 1.0.0-beta (for Mockito 1.10.x and earlier betas of Mockito 2) is available through Maven Central. The versions should be pretty stable, but I would like to get wider feedback about this new feature, so it is labeled as beta. More details can be found on the project webpage.

Acknowledge. The idea was originally proposed by David Gageot (the guy behind Infinitest) in one of his blog posts.

Mockito logo

Mockito-Java8 is a set of Mockito add-ons leveraging Java 8 and lambda expressions to make mocking with Mockito even more compact.

At the beginning of 2015 I gave my flash talk Java 8 brings power to testing! at GeeCON TDD 2015 and DevConf.cz 2015. In my speech using 4 examples I showed how Java 8 – namely lambda expressions – can simplify testing tools and testing in general. One of those tools was Mokcito. To not let my PoC code die on slides and to make it simply available for others I have released a small project with two, useful in specified case, Java 8 add-ons for Mockito.

Mockito logo

Quick introduction

As a prerequisite, let’s assume we have the following data structure:

@Immutable
class ShipSearchCriteria {
    int minimumRange;
    int numberOfPhasers;
}

The library provides two add-ons:

Lambda matcher – allows to define matcher logic within a lambda expression.

given(ts.findNumberOfShipsInRangeByCriteria(
    argLambda(sc -> sc.getMinimumRange() > 1000))).willReturn(4);

Argument Captor – Java 8 edition – allows to use ArgumentCaptor in a one line (here with AssertJ):

verify(ts).findNumberOfShipsInRangeByCriteria(
    assertArg(sc -> assertThat(sc.getMinimumRange()).isLessThan(2000)));

Lambda matcher

With a help of the static method argLambda a lambda matcher instance is created which can be used to define matcher logic within a lambda expression (here for stubbing). It could be especially useful when working with complex classes pass as an argument.

@Test
public void shouldAllowToUseLambdaInStubbing() {
    //given
    given(ts.findNumberOfShipsInRangeByCriteria(
        argLambda(sc -> sc.getMinimumRange() > 1000))).willReturn(4);
    //expect
    assertThat(ts.findNumberOfShipsInRangeByCriteria(
        new ShipSearchCriteria(1500, 2))).isEqualTo(4);
    //expect
    assertThat(ts.findNumberOfShipsInRangeByCriteria(
        new ShipSearchCriteria(700, 2))).isEqualTo(0);
}

In comparison the same logic implemented with a custom Answer in Java 7:

@Test
public void stubbingWithCustomAsnwerShouldBeLonger() {  //old way
    //given
    given(ts.findNumberOfShipsInRangeByCriteria(any())).willAnswer(new Answer<Integer>() {
        @Override
        public Integer answer(InvocationOnMock invocation) throws Throwable {
            Object[] args = invocation.getArguments();
            ShipSearchCriteria criteria = (ShipSearchCriteria) args[0];
            if (criteria.getMinimumRange() > 1000) {
                return 4;
            } else {
                return 0;
            }
        }
    });
    //expect
    assertThat(ts.findNumberOfShipsInRangeByCriteria(
        new ShipSearchCriteria(1500, 2))).isEqualTo(4);
    //expect
    assertThat(ts.findNumberOfShipsInRangeByCriteria(
        new ShipSearchCriteria(700, 2))).isEqualTo(0);
}

Even Java 8 and less readable constructions don’t help too much:

@Test
public void stubbingWithCustomAsnwerShouldBeLongerEvenAsLambda() {  //old way
    //given
    given(ts.findNumberOfShipsInRangeByCriteria(any())).willAnswer(invocation -> {
        ShipSearchCriteria criteria = (ShipSearchCriteria) invocation.getArguments()[0];
        return criteria.getMinimumRange() > 1000 ? 4 : 0;
    });
    //expect
    assertThat(ts.findNumberOfShipsInRangeByCriteria(
        new ShipSearchCriteria(1500, 2))).isEqualTo(4);
    //expect
    assertThat(ts.findNumberOfShipsInRangeByCriteria(
        new ShipSearchCriteria(700, 2))).isEqualTo(0);
}

Argument Captor – Java 8 edition

A static method assertArg creates an argument matcher which implementation internally uses ArgumentMatcher with an assertion provided in a lambda expression. The example below uses AssertJ to provide meaningful error message, but any assertions (like native from TestNG or JUnit) could be used (if really needed). This allows to have inlined ArgumentCaptor:

@Test
public void shouldAllowToUseAssertionInLambda() {
    //when
    ts.findNumberOfShipsInRangeByCriteria(searchCriteria);
    //then
    verify(ts).findNumberOfShipsInRangeByCriteria(
        assertArg(sc -> assertThat(sc.getMinimumRange()).isLessThan(2000)));
}

In comparison to 3 lines in the classic way:

@Test
public void shouldAllowToUseArgumentCaptorInClassicWay() {  //old way
    //when
    ts.findNumberOfShipsInRangeByCriteria(searchCriteria);
    //then
    ArgumentCaptor<ShipSearchCriteria> captor = 
        ArgumentCaptor.forClass(ShipSearchCriteria.class);
    verify(ts).findNumberOfShipsInRangeByCriteria(captor.capture());
    assertThat(captor.getValue().getMinimumRange()).isLessThan(2000);
}

Summary

The presented add-ons were created as PoC for my conference speech, but should be fully functional and potentially useful in the specific cases. To use it in your project it is enough to use Mockito 1.10.x or 2.0.x-beta, add mockito-java8 as a dependency and of course compile your project with Java 8+.

More details are available on the project webpage: https://github.com/szpak/mockito-java8

Update 20151217. You may be also interested in my new blog post about using Mockito wihtout static imports.

Quick tutorial how to promote/release artifacts in a Gradle project to Maven Central, without clicking in the Nexus GUI with Gradle Nexus Staging Plugin.

Introduction

Maven Central (aka The Central Repository) is (probably) the world’s largest set of open source artifacts used by Java and JVM-based projects. It was founded by the creators of Apache Maven and it has been serving artifacts since 2002. Nowadays there are some alternatives (listed below), but for many users Maven Central is still the primary source of project dependencies (and sometimes the only one whitelisted in the corporations).

The Central Repository logo

Problem

To perform the release to The Central Repository, Maven users can use Nexus Staging Maven Plugin – free, but not fully open source plugin. But with Gradle it was required to login into Nexus GUI and manually invoke two actions (close repository and release/promote repository). Quite boring and in addition highly problematic with the Continuous Delivery approach. Luckily Nexus exposes REST API which with some work allows to do the same. Gradle Nexus Staging Plugin arose to do that job.

Quick start

Important. Please pay attention that the prerequisite is to have an active and configured account in Sonatype OSSRH (OSS Repository Hosting) as well as Gradle project configured to publish release artifacts to staging repository. If you don’t have it already please follow a separate section for Gradle in the official guide.

To setup automatic release/promotion in your project add gradle-nexus-staging-plugin to the buildscript dependencies in your build.gradle file for root project:

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath "io.codearte.gradle.nexus:gradle-nexus-staging-plugin:0.5.1"
    }
}

Apply the plugin:

apply plugin: 'io.codearte.nexus-staging'

Configure it:

nexusStaging {
    packageGroup = "org.mycompany.myproject"
    stagingProfileId = "yourStagingProfileId" //when not defined will be got from server using "packageGroup"
}

After successful archives upload (with maven, maven-publish or nexus plugin) to Sonatype OSSRH call:

./gradlew closeRepository promoteRepository

to close staging repository and promote/release it and its artifacts. If a synchronization with Maven Central was enabled the artifacts should automatically appear into Maven Central within several minutes.

Details

The plugin provides two main task:

  • closeRepository – closes the open repository with uploaded artifacts. There should be just one open repository available in the staging profile (possible old/broken repositories can be dropped with Nexus GUI)
  • promoteRepository – promotes/releases closed repository (required to put artifacts to Maven Central)

And one additional:

  • getStagingProfile – gets and displays staging profile id for a given package group. This is a diagnostic task to get the value and put it into the configuration closure as stagingProfileId. To see the result it is required to call gradle with --info switch.

It has to be mentioned that calling Nexus REST API ends immediately, but the closing operation takes a moment, so to make it possible to call closeRepository promoteRepository together there is a built-in retry mechanism.

The plugin is “upload mechanism agnostic” and can be used together with maven, maven-plugin or nexus plugins.

For more details and configuration parameters see project webpage or the working example in the plugin’s own release configuration.

Alternatives to Maven Central?

There is much younger, but promising alternative – Bintray which also allows to serve artifacts. It is free for open source projects and I personally had used it for some other projects and even created an automatic release mechanism for Bintray, Travis and Gradle. It works ok, but to put artifacts also to Maven Central it is required to store a private key used for singing on their servers and in addition provide Nexus credentials. It increases the risk to have them stolen and in Codearte we prefer to use private Jenkins instance to perform the release directly to Maven Central.

Summary

With Gradle Nexus Staging Plugin the whole release process to Maven Central can be performed with Gradle from a command line and with some additional work completely automatic from a CI server. No more buttons to push in Nexus GUI. In addition to Sonatype OSSRH the plugin can be also used with private Nexus instances with enabled staging repositories.

Btw, there possibly are many things that could be enhancement in the plugin. If you need something or found a bug feel free to use issue tracker to report that.

Thanks to Kuba Kubryński for motivation and help with analyzing the not very well documented Nexus REST API.

When writing integration tests it is sometimes required to set up environment initial conditions/state before/after a given test or the whole specification. Upcoming Spock 1.0 expands the number of available options to do it in the convenient way.

This is the second part of the series about new and noteworthy in (upcoming) Spock 1.0.

New extension @RestoreSystemProperties

System properties provides information about JVM configuration and the environment like JVM vendor and version, operating system, classpath, locale or a time zone. Some of them can impact the way our application works. The following example checks if the protection before running a dangerous program as root works properly on Unix machines. To not affect other tests @RestoreSystemProperties restores the original system properties.

@Stepwise
class RestoreSystemPropertiesSpec extends Specification {

    @RestoreSystemProperties
    def "should deny perform action when running as root"() {
        given:
            System.setProperty("user.name", "root")
        and:
            def sut = new DangerousActionPerformer()
        when:
            sut.squashThemAll()
        then:
            thrown(IllegalStateException)
    }

    def "should perform action when running as 'normal' user"() {
        given:
            def sut = new DangerousActionPerformer()
        when:
            sut.squashThemAll() //current user name was restored
        then:
            noExceptionThrown()
    }

    (...)
}

The extension can be activated using @RestoreSystemProperties annotation. It can be placed on a feature method to be applied right after the given test only or on a class to restore system properties after every test in the specification. The behavior in the second case is identical to placing the annotation on every test method.

Internally Spock makes a copy of a system Properties structure before a test and restores it after.

@ConfineMetaClassChanges (since 0.7)

One of the things which make Groovy language so powerful is metaprogramming – an ability to modify classes (e.g. add/modify new methods) at runtime. That could look like hacking (and that is true), but in some specific cases it is very useful (see Grails and GORM for creating database queries when non existing methods – like findByFirstNameAndSecondName(...) or writing a custom DSL like 6.minutes.ago).

MetaClass operations are usually executed at the class (not instance) level what generally causes that they affect every class instance in given class loader. GORM like changes done in multiple test could interact each other causing tests to fail. For that cases @ConfineMetaClassChanges extension (available already in previous Spock version) was created.

@Stepwise
class ConfineMetaClassChangesSpec extends Specification {

    @ConfineMetaClassChanges(EmptyClass)
    def "should allow to call added method"() {
        given:
            EmptyClass.metaClass.returnFoo = { "foo" }
        when:
            def fooValue = new EmptyClass().returnFoo()
        then:
            fooValue == "foo"

    }

    def "should throw exception on not available method"() {
        when:
            new EmptyClass().returnFoo()
        then:
            thrown(MissingMethodException)
    }
}

class EmptyClass {
}

@ConfineMetaClassChanges annotation can be placed on a feature method to restore MetaClass to the state just before that test or on a class to restore system properties after the last test in the specification to the state before calling the setupSpec method.

Note that @ConfineMetaClassChanges behavior placed on a specification level is different (once after the last test) than @RestoreSystemProperties behavior (every time after every test).

@AutoCleanup (since 0.7)

Another already existing, but rarely known and used extension is @AutoCleanup. Usually external resources are allocated in setup/setupSpec methods and released in cleanup/cleanupSpec methods. But Spock, the same as pure JUnit, support auto initialization instance variables (fields) before every test/feature (which overrides default Java behavior when a field is initialized only once when a class instance is created).

class ManualCleanupSpec extends Specification {

    @Shared
    private DBConnection dbConnection = new H2DBConnection()

    void cleanupSpec() {
        dbConnection.close()    //boilerplate code
    }

    def "should do fancy thing on DB"() {
        ...
    }
}

interface DBConnection {
    void close()
}

To make it easier to release those inlined resources can be annotated with @AutoCleanup to call close method (or any other method defined as a parameter) in the clean up phase.

class AutoCleanupSpec extends Specification {

    @AutoCleanup
    @Shared
    private DBConnection dbConnection = new H2DBConnection()

    def "should do fancy thing on DB"() {
        ...
    }
}

@AutoCleanup supports both instance variables (the method is called after every tests) and static/@Shared fields (the clean up is performed after the last test). All errors during clean up are caught to not interrupt test execution. By default there are logged, which can be disabled using quiet parameter @AutoCleanup(quiet = true).

Where can I find Spock 1.0?

Please notice that blog post is about features available in Git branch planned to become Spock 1.0 sometime in the future. They are currently available only in a 1.0-SNAPSHOT version in a separate repository. As not being released (at the time of writing) they could look different or even (in the extreme case) be not available in the final version. Be aware.

To add Spock 1.0 as a dependency to your project define snapshot repository https://oss.sonatype.org/content/repositories/snapshots/ and the Spock artifact in version 1.0-groovy-2.0-SNAPSHOT. Sample configuration in Gradle:

repositories {
    ...
    maven { url "https://oss.sonatype.org/content/repositories/snapshots/" }
}

dependencies {
    ...
    testCompile ('org.spockframework:spock-core:1.0-groovy-2.0-SNAPSHOT')
}

Summary

Mentioned extensions were designed for integration tests and because of class loader (or system) wide changes it is not safe to execute more than one test in the same time. Therefore it is important to separate pure, very fast and independent, unit tests from integration tests to (inter alia) allow unit tests to run in parallel.

After @Require and @IgnoreIf this is the second post about changes in upcoming Spock 1.0. The examples was written using Spock 1.0-groovy-2.0-SNAPSHOT and they can cloned from GitHub.

May the Spock be with you!

Introduction

Some tests (especially integration tests) should be run only if certain conditions are (or are not) met. Upcoming Spock 1.0 provides new @Requires and improved @IgnoreIf extensions to handle that requirement in a convenient way.

Historical background – waiting for Spock 1.0

The latest stable Spock version (0.7) has been released in October 2012 (~2 years as the time of writing). There have been made hundreds of commits to Git repository since then and many new features and improvements are already available in the current SNAPSHOT version. Unfortunately the “New and Noteworthy” section in the documentation doesn’t cover those changes and the only way (as I know) to get them know is digging into Git commits. As a Spock user I was curious what new is around the corner, so I did that job which resulted in the presentation at Confitura (in Polish). A as bonus I planned a series of blog entries describing those more interesting features and possibly also an update of Spock documentation.

This is just the first part of the changes in (upcoming) Spock 1.0. There is much more to discover and I will be presenting that in future blog posts.

New extension @Requires

@Requires allows to run given test (or the whole specification) only if given criteria are met.

    @Requires({ System.getProperty("os.arch") == "i386" })
    def "should use native libraries on 32-bit JVM"() { ... }

    @Requires({ env.containsKey("ENABLE_CRM_INTEGRATION_TESTS") })
    def "should do complicated things with CRM"() { ... }

It is opposite to already known from Spock 0.7 @Ignore extension which allowed to ignore the given test (or the whole specification) using access to system properties (propertiesSystem.getProperties()), environment variables (envSystem.getenv()) and java version (javaVersionSystem.getProperty("java.version")). In Spock 1.0 branch they both are much more powerful.

Testing my examples in practice I was surprised that a system property “os.arch” returns not a processor architecture taken from an OS, but a JVM version. So, be aware that running a 32-bit JVM on 64-bit system will return “i386”. Hopefully usually that knowledge is not important (unless for example the native libraries are used).

New features in @Requires and @IgnoreIf

In addition to the new @Requires extension it and its twin @IgnoreIf have got new internal abstraction to simplify the way how the operating system information and a JVM version can be accessed.

Operating system

Operating system information can be accessible in Spock 0.7 using os.name and os.version system properties. Unfortunately it can be complicated and error prone in some cases:

    //Run only on Linux and MacOS - in Spock 0.7 style
    @Requires({ System.getProperty("os.name").toLowerCase().contains("mac os") || 
                System.getProperty("os.name").toLowerCase().contains("darwin") || 
                System.getProperty("os.name").toLowerCase().contains("linux")  })
    def "should use fancy text console features"() { ... }

In the meantime Spock has got the new OperatingSystem abstraction which provides methods like:

    String getName() //Linux
    String getVersion() //8.1
    Family getFamily() //SOLARIS (enum)

    boolean isLinux()
    boolean isWindows()
    boolean isMacOs() //also Solaris and Other
    boolean iSolaris()
    boolean isOther()

With their help mentioned example can be simplified to very readable code precisely explaining our intentions:

    @Requires({ os.linux || os.macOs  })    //Spock 1.0 edition
    def "should use fancy text console features"() { ... }

JVM version

In addition to OperatatingSystem there is also Jvm abstraction which provides methods like:

    boolean isJava7() //true only if Java 7
    boolean isJava8Compatible() //true if Java 8+

or more generic:

    String getJavaVersion() //e.g. "1.8.0_05"
    String getJavaSpecificationVersion() //e.g. "1.8"

The original JVM version dependent test cases declaration:

    @IgnoreIf({ javaVersion < 1.8 })
    def "should find at runtime and use CompletableFuture for Java 8+"() { 
        ... 
    }

can be replaced with more verbose:

    @IgnoreIf({ !jvm.java8Compatible })
    def "should find at runtime and use CompletableFuture for Java 8+"() { 
        ... 
    }

Using static methods

@Requires (the same as @IgnoreIf) can also use static methods to define a condition (which is available, but less known in Spock 0.7). Those methods can be declared inside a given class, in an another class or (when using Groovy 2.3+) in a trait.

import static FancyFeatureRequiredIntranetConnectionSpecIT.isUrlAvailable

@Requires({ isUrlAvailable("http://some-host.intranet/") })
class FancyFeatureRequiredIntranetConnectionSpecIT extends Specification {

    //could be also from trait or other class
    static boolean isUrlAvailable(String url) { 
        //...
    }

    def "should do one thing in intranet"() { ... }

    def "should do another thing in intranet"() { ... }

    ...
}

Please pay attention to the static import in this example. Even though that code without an import looks ok and Idea sees the method it will fail at runtime with groovy.lang.MissingMethodException: No signature of method: (...). This is caused by the way how Spock internally tries to resolve references in a Closure. For detailed explanation see the next paragraph.

groovy.lang.MissingMethodException: No signature of method:
FancyFeatureRequiredIntranetConnectionSpecIT$_closure1.isUrlAvailable()
is applicable for argument types: (java.lang.String) values: [http://some-host.intranet/]

How does it internally work (for the curious)?

You may wonder how that code even compile if jvm or os are not known for the Specification class. The key thing is that code inside @Requires (and @IgnoreIf) annotation is wrapped with {} (curly brackets). In Groovy that syntax means “anonymous code block” and it is named Closure. The @Requires annotation accepts a Closure as a parameter:

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE, ElementType.METHOD})
@ExtensionAnnotation(RequiresExtension.class)
public @interface Requires {
  Class<? extends Closure> value(); // <- important line
}

Two important aspects of a Groovy Closure are used in Spock to implement those features:

  • a block of code is executed “at the later point”
  • an execution context can be delegated

The first point causes that Groovy compiler ignores unresolved references. At the compilation time the execution context can be unknown (a Closure can be passed as a parameter far away from the declaration place). The used references will be resolved at runtime and here the second point applies.

By default property references and methods are attempted to be resolved to the owner (an enclosing class or a surrounding Closure) and later to the delegate (by default the same as owner). A delegate can be changed and that is used in RequiresExtension:

    (...)
    condition.setDelegate(new PreconditionContext());
    condition.setResolveStrategy(Closure.DELEGATE_ONLY);
    return condition.call();

PreconditionContext is a delegate class for @Requires and @IgnoreIf providing an execution context. Its getOS() or getJvm() methods are resolved and executed when os or jvm properties are used in the annotation Closure. In addition to set a dedicated delegate, a resolve strategy is changed to not bother with an enclosing class and try resolve unresolved references only using PreconditionContext.

If you are new to Groovy and feel confused with the internals I propose you to take a look at the introduction to Groovy Closure. If you like it there is a lot more things to get know about Groovy Closure and its power.

Where can I find Spock 1.0?

Please notice that blog post is about features available in Git branch planned to become Spock 1.0 sometime in the future. They are currently available only in a 1.0-SNAPSHOT version in a separate repository. As not being released (as the time of writing) they could look different or even (in the extreme case) be not available in the final version. Be aware.

To add Spock 1.0 as a dependency to your project define snapshot repository http://oss.sonatype.org/content/repositories/snapshots/ and the Spock artifact in version 1.0-groovy-2.0-SNAPSHOT. Sample configuration in Gradle:

repositories {
    ...
    maven { url "http://oss.sonatype.org/content/repositories/snapshots/" }
}

dependencies {
    ...
    testCompile 'org.spockframework:spock-core:1.0-groovy-2.0-SNAPSHOT'
}

Summary

New @Requires extension and the enhancements in @IgnoreIf are the first part of the series about new and noteworthy in upcoming Spock 1.0. When will it be released? Citing John Carmack “It’ll be done when it’s done”. If you would like to bring the release closer donate your time and contribute to the project.

Post written using Spock 1.0-groovy-2.0-SNAPSHOT. Examples can be cloned from GitHub.

Test quickly and prosper :).

AssertJ and Awaitility are two of my favorites tools using in automatic code testing. Unfortunately until recently it was not possible to use it together. But then Java 8 entered the game and several dozens lines of code was enough to make it happen in Awaility 1.6.0.

Awaitility logo

AssertJ provides a rich set of assertions with very helpful error messages, all available though the fluent type aware API. Awaitility allows to express expectations of asynchronous calls in a concise and easy to read way leveraging an active wait pattern which shortens the duration of tests (no more sleep(5000)!).

The idea to use it together came into my mind a year ago when I was working on an algo trading project using Complex event processing (CEP) and I didn’t like to learn Hamcrest assertion just for asynchronous tests with Awaitility. I was able to do a working PoC, but it required to make some significant duplication in AssertJ (then FEST Assert) code and I shelved the idea. A month ago I was preparing my presentation about asynchronous code testing for the 4Developers conference and asked myself a question: How Java 8 could simplify the usage of Awaitility?

For the few examples I will use asynchronousMessageQueue which can be used to send ping request and return number of received packets. One of the ways to test it with Awaitility in Java 7 (besides proxy based condition) is to create a Callable class instance:

    @Test
    public void shouldReceivePacketAfterWhileJava7Edition() {
        //when
        asynchronousMessageQueue.sendPing();
        //then
        await().until(receivedPackageCount(), equalTo(1));
    }

    private Callable<Integer> receivedPackageCount() {
        return new Callable<Integer>() {
            @Override
            public Integer call() throws Exception {
                return asynchronousMessageQueue.getNumberOfReceivedPackets();
            }
        };
    }

where equalTo() is a standard Hamcrest matcher.

The first idea to reduce verbosity is to replace Callable with a lambda expression and inline the private method:

    @Test
    public void shouldReceivePacketAfterWhile() {
        //when
        asynchronousMessageQueue.sendPing();
        //then
        await().until(() -> asynchronousMessageQueue.getNumberOfReceivedPackets(), equalTo(1));
    }

Much better. Going forward lambda expression can be replaced with a method reference:

    @Test
    public void shouldReceivePacketAfterWhile() {
        //when
        asynchronousMessageQueue.sendPing();
        //then
        await().until(asynchronousMessageQueue::getNumberOfReceivedPackets, equalTo(1));
    }

Someone could go even further and remove Hamcrest matcher:

    @Test
    public void shouldReceivePacketAfterWhile() {
        //when
        asynchronousMessageQueue.sendPing();
        //then
        await().until(() -> asynchronousMessageQueue.getNumberOfReceivedPackets() == 1);  //poor error message
    }

but while it still works the error message becomes much less meaningful:

ConditionTimeoutException: Condition with lambda expression in
AwaitilityAsynchronousShowCaseTest was not fulfilled within 2 seconds.

instead of very clear:

ConditionTimeoutException: Lambda expression in AwaitilityAsynchronousShowCaseTest
that uses AbstractMessageQueueFacade: expected <1> but was <0> within 2 seconds.>

The solution would be to use AssertJ assertion inside lambda expression:

    @Test
    public void shouldReceivePacketAfterWhileAssertJEdition() {
        //when
        asynchronousMessageQueue.sendPing();
        //then
        await().until(() -> assertThat(asynchronousMessageQueue.getNumberOfReceivedPackets()).isEqualTo(1));
    }

and thanks to the new AssertionCondition initially hacked within a few minutes it became a reality in Awaitility 1.6.0. Of course AssertJ fluent API and meaningful failure messages for different data types are preserved.

As a bonus all assertions that throw AssertionError (so particularly TestNG and JUnit standard assertions) can be used in the lambda expression as well (but I don’t know anyone who came back to “standard” assertion knowing the power of AssertJ).

The nice thing is that the changes itself leverage Runnable class to implement lambdas and AssertJ support and Awaitility 1.6.0 is still Java 5 compatible. Nevertheless for the sake of readability it is only sensible to use the new constructions in Java 8 based projects.

Btw, here are the “slides” from my presentation at 4Developers.

4developers logo