(Quick Reference)

9. Testing - Reference Documentation

Authors: Graeme Rocher, Peter Ledbrook, Marc Palmer, Jeff Brown, Luke Daley, Burt Beckwith

Version: 1.4.0.M1

9. Testing

Automated testing is seen as a key part of Grails. Hence, Grails provides many ways to making testing easier from low level unit testing to high level functional tests. This section details the different capabilities that Grails offers in terms of testing.

Grails 1.3.x and below used the grails.test.GrailsUnitTestCase class hierarchy for testing in a JUnit 3 style. Grails 1.4.x and above deprecates these test harnesses in favour of mixins that can be applied to a range of different kinds of tests (JUnit 3, Junit 4, Spock etc.)

The first thing to be aware of is that all of the create-* commands actually end up creating unit tests automatically for you. For example say you run the create-controller command as follows:

grails create-controller com.acme.app.simple

Not only will Grails create a controller at grails-app/controllers/com/acme/app/SimpleController.groovy, but also a unit test at test/unit/com/acme/app/SimpleControllerTests.groovy. What Grails won't do however is populate the logic inside the test! That is left up to you.

As of Grails 1.2.2,the suffix of Test is also supported for test cases.

Running Tests

Test are run with the test-app command:

grails test-app

Note that you will be able to run unit tests much quicker if you use an IDE or if you use the grails interactive command to start-up Grails in interactive mode, thus preventing the need to stop the JVM:

grails interactive

The test-app command will produce output such as:

Running Unit Tests…
Running test FooTests...FAILURE
Unit Tests Completed in 464ms …

Tests failed: 0 errors, 1 failures

Whilst reports will have been written out the target/test-reports directory.

You can force a clean before running tests by passing -clean to the test-app command.

Targeting Tests

You can selectively target the test(s) to be run in different ways. To run all tests for a controller named SimpleController you would run:

grails test-app SimpleController

This will run any tests for the class named SimpleController. Wildcards can be used...

grails test-app *Controller

This will test all classes ending in Controller. Package names can optionally be specified...

grails test-app some.org.*Controller

or to run all tests in a package...

grails test-app some.org.*

or to run all tests in a package including subpackages...

grails test-app some.org.**.*

You can also target particular test methods...

grails test-app SimpleController.testLogin

This will run the testLogin test in the SimpleController tests. You can specify as many patterns in combination as you like...

grails test-app some.org.* SimpleController.testLogin BookController

Targeting Test Types and/or Phases

In addition to targeting certain tests, you can also target test types and/or phases by using the phase:type syntax.

Grails organises tests by phase and by type. A test phase relates to the state of the Grails application during the tests, and the type relates to the testing mechanism.

Grails comes with support for 4 test phases (unit, integration, functional and other) and JUnit test types for the unit and integration phases. These test types have the same name as the phase.

Testing plugins may provide new test phases or new test types for existing phases. Refer to the plugin documentation.

To execute the JUnit integration tests you can run:

grails test-app integration:integration

Both phase and type are optional. Their absence acts as a wildcard. The following command will run all test types in the unit phase:

grails test-app unit:

The Grails Spock Plugin is one plugin that adds new test types to Grails. It adds a spock test type to the unit, integration and functional phases. To run all spock tests in all phases you would run the following:

grails test-app :spock

To run the all of the spock tests in the functional phase you would run...

grails test-app functional:spock

More than one pattern can be specified...

grails test-app unit:spock integration:spock

Targeting Tests in Types and/or Phases

Test and type/phase targetting can be applied at the same time:

grails test-app integration: unit: some.org.**.*

This would run all tests in the integration and unit phases that are in the page some.org or a subpackage of.

9.1 Unit Testing

Unit testing are tests at the "unit" level. In other words you are testing individual methods or blocks of code without consideration for surrounding infrastructure. Unit tests are typically run without the presence of physical resources that involve I/O such databases, socket connections or files. This is to ensure they run as quick as possible since quick feedback is important.

Since Grails 1.4, a collection of unit testing mixins is provided by Grails that allows you to enhance the behavior of a typical JUnit 3, JUnit 4 or Spock test. The following sections cover the usage of these mixins.

The previous JUnit 3-style GrailsUnitTestCase class hierarchy is still present in Grails for backwards compatibility, but is now considered as deprecated. The previous documentation on the subject can be found in the Grails 1.3.x documentation

9.1.1 Unit Testing Controllers

The Basics

To unit test controllers you use the grails.test.mixin.TestFor annotation to target a particular controller. Using TestFor in this manner activates the grails.test.mixin.web.ControllerUnitTestMixin and its associated API. For example:

import grails.test.mixin.*

@TestFor(SimpleController) class SimpleControllerTests { void testSomething() {

} }

By defining the TestFor annotation for a controller a new controller field is automatically created for the controller under test.

The TestFor annotation will also automatically annotate any public methods starting with "test" with JUnit 4's @Test annotation. If your test method doesn't start with "test" you will need to add this manually

To test the simplest "Hello World"-style example you can do the following:

// Test class
class SimpleController {
    def hello() {
        render "hello"

void testHello() { controller.hello()

assert response.text == 'hello' }

The response object is an instance of GrailsMockHttpServletResponse (in the package org.codehaus.groovy.grails.plugins.testing) which extends Spring's org.springframework.mock.web.MockHttpServletResponse and has a number of useful methods for inspecting the state of the response.

For example to test a redirect you can use the redirectUrl property:

// Test class
class SimpleController {
    def index() {
        redirect action:'hello'

void testIndex() { controller.index()

assert response.redirectedUrl == '/simple/hello' }

Testing View Rendering

To test view rendering you can inspect the state of the controller's modelAndView property which is an instance of org.springframework.web.servlet.ModelAndView or you can use the view and model properties provided by the mixin:

// Test class
class SimpleController {
    def home() {
        render view:"homePage", model:[title:"Hello World"]

void testIndex() { controller.home()

assert view == "/simple/homePage" assert model.title == "Hello World" }

Testing Template Rendering

Unlike view rendering, template rendering will actually attempt to write the template directly to response rather than returning a ModelAndView hence it requires a different approach to testing.

Consider the following controller action:

class SimpleController {
    def display() {
        render template:"snippet"

In this example the controller will look for a template in grails-app/views/simple/_snippet.gsp. You can test this as follows:

void testDisplay() {
    assert response.text == 'contents of template'

However, you may not want to render the real template, but merely test that is was rendered. In this case you can provide mock Groovy Pages:

void testDisplay() {
    views['/simple/_snippet.gsp'] = 'mock contents'
    assert response.text == 'mock contents'

Testing XML and JSON Responses

XML and JSON response are also written directly to the response. Grails' mocking capabilities provide some conveniences for testing XML and JSON response. For example consider the following action:

def renderXml() {
    render(contentType:"text/xml") {

This can be tested using the xml property of the response:

void testRenderXml() {
    assert "<book title='Great'/>" == response.text
    assert "Great" == response.xml.@title.text()

The xml property is a parsed result from Groovy's XmlSlurper class which is very convenient for parsing XML.

Testing JSON responses is pretty similar, instead you use the json property:

// controller action
def renderJson() {
    render(contentType:"text/json") {
        book = "Great"

// test void testRenderJson() {


assert '{"book":"Great"}' == controller.response.text assert "Great" == response.json.book }

The json property is an instance of org.codehaus.groovy.grails.web.json.JSONElement which is a map-like structure that is useful for parsing JSON responses.

Testing Spring Beans

When using TestFor only a subset of the Spring beans available to a running Grails application are available. If you wish to make additional beans available you can do so with the defineBeans method of GrailsUnitTestMixin:

class SimpleController {
    SimpleService simpleService
    def hello() {
        render simpleService.sayHello()

void testBeanWiring() { defineBeans { simpleService(SimpleService) }


assert response.text == "Hello World" }

The controller is auto-wired via Spring just like in a running Grails application. Autowiring even occurs if you instantiate subsequent instances of the controller:

void testAutowiringViaNew() {
    defineBeans {

def controller1 = new SimpleController() def controller2 = new SimpleController()

assert controller1.simpleService != null assert controller2.simpleService != null }

Testing Mime Type Handling

You can test mime type handling and the withFormat method quite simply by setting the request's format attribute:

// controller action
def sayHello() {
    def data = [Hello:"World"]
    withFormat {
        xml { render data as XML }
        html data

// test void testSayHello() { request.format = 'xml' controller.sayHello()

assert '<?xml version="1.0" encoding="UTF-8"?><map><entry key="Hello">World</entry></map>' == response.text }

Testing Duplicate Form Submissions

Testing duplicate form submissions is a little bit more involved. Say for example you have an action that handles a form such as:

def handleForm() {
    withForm {
        render "Good"
    }.invalidToken {
        render "Bad"

You want to verify the logic that is executed on a good form submission and the logic that is executed on a duplicate submission. Testing the bad submission is simple. Just invoke the controller:

void testDuplicateFormSubmission() {
    assert "Bad" == response.text	

Testing the successful submission requires providing an appropriate SynchronizerTokenHolder:

import org.codehaus.groovy.grails.web.servlet.mvc.SynchronizerTokenHolder

void testValidFormSubmission() { def holder = SynchronizerTokensHolder.store(session) def token = holder.generateToken('/test') params[SynchronizerTokensHolder.TOKEN_URI] = '/test' params[SynchronizerTokensHolder.TOKEN_KEY] = token

controller.handleForm() assert "Good" == response.text }

If you wish to test both the valid and the invalid request in the same test you will need to reset the response between executions of the controller:

controller.handleForm() // first execution
controller.handleForm() // second execution

Testing File Upload

To test file uploads you need to use the GrailsMockMultipartFile class. For example consider the following controller action:

def uploadFile() {
    MultipartFile file = request.getFile("myFile")
    file.transferTo(new File("/local/disk/myFile"))

To test this action you can register a GrailsMockMultipartFile with the request:

void testFileUpload() {
    final file = new GrailsMockMultipartFile("myFile", "foo".bytes)

assert file.targetFileLocation.path == "/local/disk/myFile" }

The GrailsMockMultipartFile takes the name of the file and the contents of the file as arguments to the constructor. It has a mock implementation of the transferTo method that simply records the targetFileLocation and doesn't write to disk.

Testing Command Objects

Special support exists for testing command object handling via the mockCommandObject method. For example consider the following action:

def handleCommand = { SimpleCommand simple ->
     if(simple.hasErrors()) {
         render "Bad"
     else {
         render "Good"

To test this you need to mock the command object, populate it and then validate it as follows:

void testInvalidCommand() {
    def cmd = mockCommandObject(SimpleCommand)
    cmd.name = '' // doesn't allow blank names

cmd.validate() controller.handleCommand(cmd)

assert response.text == 'Bad' }

Testing Calling Tag Libraries

You can test calling tag libraries using ControllerUnitTestMixin, although the mechanism for testing the tag called varies from tag to tag. For example to test a call to the message tag you need to add a message to the messageSource. For example consider the following action:

def showMessage() {
    render g.message(code:"foo.bar")

This can be tested as follows:

void testRenderBasicTemplateWithTags() {
    messageSource.addMessage("foo.bar", request.locale, "World")


assert response.text == "Hello World" }

9.1.2 Unit Testing Tag Libraries

The Basics

Tag libraries and GSP pages can be tested with the grails.test.mixin.web.GroovyPageUnitTestMixin test mixin. To use the mixin declare which tag library is under test with the TestFor annotation:

class SimpleTagLibTests {


Note that if you are testing invocation of a custom tag from a controller you can combine the ControllerUnitTestMixin and the GroovyPageUnitTestMixin using the Mock annotation:

class GroovyPageUnitTestMixinTests {


Testing Custom Tags

The core Grails tags don't need to be enabled during testing, however custom tag libraries do. The GroovyPageUnitTestMixin class provides a mockTagLib(Class) method that you can use to mock a custom tag library. For example consider the following tag library:

class SimpleTagLib {
    static namespace = 's'

def hello = { attrs, body -> out << "Hello ${attrs.name ?: 'World'}" } }

You can test this tag library by using TestFor and supplying the name of the tag library:

class SimpleTagLibTests {
    void testHelloTag() {
        assert applyTemplate('<s:hello />')	== 'Hello World'
        assert applyTemplate('<s:hello name="Fred" />') == 'Hello Fred'

Alternatively, you can use the TestMixin annotation and mock multiple tag libraries via the mockTagLib(Class) method:

class MultipleTagLibraryTests {

@Test void testMuliple() { mockTagLib(FirstTagLib) mockTagLib(SecondTagLib)

… } }

Testing View and Template Rendering

You can test rendering of views and templates in grails-app/views via the render(Map) method provided by GroovyPageUnitTestMixin :

def result = render(template:"/simple/hello")
assert result == "Hello World"

This will attempt to render a template found at the location grails-app/views/simple/_hello.gsp. Note that if the template depends on any custom tag libraries you will need to call mockTagLib as described in the previous section.

9.1.3 Unit Testing Domains


Domain class interaction can be tested without involving a database connection using the DomainClassUnitTestMixin. This implementation mimics the behavior of GORM against an in-memory ConcurrentHashMap implementation. Note that it contains limitations in comparison to a real GORM implementation. The following features of GORM for Hibernate can only be tested within an integration test:

  • String-based HQL queries
  • Composite Identifiers
  • Dirty Checking Methods
  • Any Direct Interaction with Hibernate

However, a large, commonly-used portion of the GORM API can be mocked via DomainClassUnitTestMixin including:

  • Simple persistence methods like save(), delete() etc.
  • Dynamic Finders
  • Named Queries
  • Query-by-example
  • GORM Events

If something isn't supported then GrailsUnitTestMixin's mockFor method can come in handy to mock the missing pieces. Alternatively you can write an integration test which bootstraps the complete Grails environment at a cost of test execution time.

The Basics

DomainClassUnitTestMixin is typically used in combination with testing either a controller, service of tag library where the domain is a mock collaborator defined via the Mock annotation:

import grails.test.mixin.*

@TestFor(SimpleController) @Mock(Simple) class SimpleControllerTests {


The example above tests the SimpleController class and mocks the behavior of the Simple domain class as well. For example consider a typical scaffolded save controller action:

class BookController {
    def save = {
        def book = new Book(params)
        if (book.save(flush: true)) {
            flash.message = message(
                    code: 'default.created.message',
                    args: [message(code: 'book.label', default: 'Book'), book.id])}"
            redirect(action: "show", id: book.id)
        else {
            render(view: "create", model: [bookInstance: book])

Tests for this action can be written as follows:

import grails.test.mixin.*

@TestFor(BookController) @Mock(Book) class BookControllerTests { void testSaveInvalidBook() { controller.save()

assert model.bookInstance != null assert view == '/book/create' } void testSaveValidBook() { params.title = "The Stand" params.pages = "500"


assert response.redirectedUrl == '/book/show/1' assert flash.message != null assert Book.count() == 1

} }

If you have more than one domain to mock the Mock annotation takes a list of mock collaborators:

@Mock([Book, Author])
class BookControllerTests {

Alternatively you can also use the DomainClassUnitTestMixin directly via the TestMixin annotation:

class BookControllerTests {

And then call the mockDomain method to mock domains during your test:

void testSave() {

The mockDomain method also includes an additional parameter that allows you to pass a map of maps to setup an domain, which is useful for fixture-like data:

void testSave() {
    mockDomain(Book, [
            [title:"The Stand", pages:"1000"],
            [title:"The Shining", pages:400],
            [title:"Along Came a Spider", pages:300] ])

Testing Constraints

Your constraints contain logic and that logic is highly susceptible to bugs - the kind of bugs that can be tricky to track down (particularly as save() doesn't throw an exception when it fails). If your answer is that it's too hard or fiddly, that is no longer an excuse. Enter the mockForConstraintsTests() method.

This method is like a much reduced version of the mockDomain() method that simply adds a validate() method to a given domain class. All you have to do is mock the class, create an instance with field values, and then call validate(). You can then access the errors property on your domain instance to find out whether the validation failed or not. So if all we are doing is mocking the validate() method, why the optional list of test instances? That is so that we can test unique constraints as you will soon see.

So, suppose we have a simple domain class like so:

class Book {
    String title
    String author
    static constraints = {
        title(blank: false, unique: true)
        author(blank: false, minSize: 5)

Don't worry about whether the constraints are sensible or not (they're not!), they are for demonstration only. To test these constraints we can do the following:

class BookTests  {
    void testConstraints() {

def existingBook = new Book( title: "Misery", author: "Stephen King")

mockForConstraintsTests(Book, [ existingBook ])

// Validation should fail if both properties are null. def book = new Book()

assert !book.validate() assert "nullable" == book.errors["title"] assert "nullable" == book.errors["author"]

// So let's demonstrate the unique and minSize constraints.

book = new Book(title: "Misery", author: "JK") assert !book.validate() assert "unique" == book.errors["title"]

assert "minSize" == book.errors["author"]

// Validation should pass! book = new Book(title: "The Shining", author: "Stephen King") assert book.validate() } }

You can probably look at that code and work out what's happening without any further explanation. The one thing we will explain is the way the errors property is used. First, it does return a real Spring Errors instance, so you can access all the properties and methods you would normally expect. Second, this particular Errors object also has map/property access as shown. Simply specify the name of the field you are interested in and the map/property access will return the name of the constraint that was violated. Note that it is the constraint name , not the message code (as you might expect).

That's it for testing constraints. One final thing we would like to say is that testing the constraints in this way catches a common error: typos in the "constraints" property! It is currently one of the hardest bugs to track down normally, and yet a unit test for your constraints will highlight the problem straight away.

9.1.4 Unit Testing Filters

Unit testing filters is typically a matter of testing a controller where a filter is a mock collaborator. For example consider the following filters class:

class CancellingFilters {
    def filters = {
        all(controller:"simple", action:"list") {
            before = {
                return false

This filter interceptors the list action of the simple controller and redirects to the book controller. To test this filter you start off with a test that targets the SimpleController class and add the CancellingFilters as a mock collaborator:

class SimpleControllerTests {


You can then implement a test that uses the withFilters method to wrap the call to an action in filter execution:

void testInvocationOfListActionIsFiltered() {
    withFilters(action:"list") {
    assert response.redirectedUrl == '/book'


Note that the action parameter is required because it is unknown what the action to invoke is until the action is actually called. The controller parameter is optional and taken from the controller under test. If it is a another controller you are testing then you can specify it:

withFilters(controller:"book",action:"list") {

9.1.5 Unit Testing URL Mappings

The Basics

Testing URL mappings can be done via the TestFor annotation testing a particular URL mappings class. For example to test the default URL mappings you can do the following:

class UrlMappingsTests {


Note that since the default UrlMappings class is in the default package your test will need to be in the default package too

With that done there are a number of useful methods that are defined by the grails.test.mixin.web.UrlMappingsUnitTestMixin for testing URL mappings. These include:

  • assertUrlMapping - Asserts a URL mappings is valid for the given URL. This combines the assertForwardUrlMapping and assertReverseUrlMapping assertions
  • assertForwardUrlMapping - Asserts a URL mapping is forwarded for the given controller class (note that controller will need to be defined as a mock collaborate for this to work)
  • assertReverseUrlMapping - Asserts that the given URL is produced when reverse mapping a link to a given controller and action

Asserting Forward URL Mappings

If you simply want to assert that a given URL maps to a given controller then assertForwardUrlMapping can help. For example, take the following URL mappings:

static mappings = {
    "/action1"(controller: "simple", action: "action1")
    "/action2"(controller: "simple", action: "action2")

The following test can be written to assert these URL mappings:

void testUrlMappings() {
    assertForwardUrlMapping("/action1", controller:'simple', action: "action1")
    assertForwardUrlMapping("/action2", controller:'simple', action: "action2")
    shouldFail {
        assertForwardUrlMapping("/action2", controller:'simple', action: "action1")

Assert Reverse URL Mappings

If you want to check that the right links are produced for your URL mapping when using the link tag in GSP views then assertReverseUrlMapping can be used. An example test is largely identical to the previous listing except you use assertReverseUrlMapping instead of assertForwardUrlMapping. Note that you can combine these 2 assertions with assertUrlMapping.

Simulating Controller Mapping

In addition to the assertions to assert the validity of URL mappings you can also simulate mapping to a controller by using your UrlMappings as a mock collaborator and the mapURI method. For example:

class SimpleControllerTests {
    void testControllerMapping() {
        SimpleController controller = mapURI('/simple/list')

assert controller != null def model = controller.list()

assert model != null } }

9.1.6 Mocking Collaborators

Beyond the specific targeted mocking APIs there is also a all-purpose mockFor() method that is available whenever using the TestFor annotation. The signature of the mockFor is:

mockFor(class, loose = false)

General purpose mocking that allows you to set up either strict or loose demands on a class.

This method is surprisingly intuitive to use. By default it will create a strict mock control object (one for which the order in which methods are called is important) that you can use to specify demands:

def strictControl = mockFor(MyService)
strictControl.demand.someMethod(0..2) { String arg1, int arg2 -> … }
strictControl.demand.static.aStaticMethod {-> … }

Notice that you can mock static methods as well as instance ones simply by using the "static" property after "demand". You then specify the name of the method that you want to mock with an optional range as its argument. This range determines how many times you expect the method to be called, so if the number of invocations falls outside of that range (either too few or too many) then an assertion error will be thrown. If no range is specified, a default of "1..1" is assumed, i.e. that the method must be called exactly once.

The last part of a demand is a closure representing the implementation of the mock method. The closure arguments should match the number and types of the mocked method, but otherwise you are free to add whatever you want in the body.

As we mentioned before, if you want an actual mock instance of the class that you are mocking, then you need to call mockControl.createMock(). In fact, you can call this as many times as you like to create as many mock instances as you need. And once you have executed the test method, you can call mockControl.verify() to check whether the expected methods were actually called or not.

Lastly, the call:

def looseControl = mockFor(MyService, true)

will create a mock control object that has only loose expectations, i.e. the order that methods are invoked does not matter.

9.2 Integration Testing

Integration tests differ from unit tests in that you have full access to the Grails environment within the test. Grails will use an in-memory HSQLDB database for integration tests and clear out all the data from the database in between each test.

One thing to bear in mind is that logging is enabled for your application classes, but that is different from logging in tests. So if you have something like this:

class MyServiceTests extends GroovyTestCase {
    void testSomething() {
        log.info "Starting tests"

the "starting tests" message is logged using a different system to the one used by the application. Basically the log property in the example above is an instance of java.util.logging.Logger, which doesn't have exactly the same methods as the log property injected into your application artifacts. For example, it doesn't have debug() or trace() methods, and the equivalent of warn() is in fact warning().


The integration tests run inside a database transaction by default, which is then rolled back at the end of the tests. This means that data saved during the tests is not persisted to the database. If you actually want to check transactional behaviour of your services and controllers, then you can disable a test's transaction by adding a transactional property to your test case:

class MyServiceTests extends GroovyTestCase {
    static transactional = false

void testMyTransactionalServiceMethod() { … } }

Testing Controllers

To test controllers you first have to understand the Spring Mock Library.

Essentially Grails automatically configures each test with a MockHttpServletRequest, MockHttpServletResponse, and MockHttpSession which you can then use to perform your tests. For example consider the following controller:

class FooController {

def text = { render "bar" }

def someRedirect = { redirect(action:"bar") } }

The tests for this would be:

class FooControllerTests extends GroovyTestCase {

void testText() { def fc = new FooController() fc.text() assertEquals "bar", fc.response.contentAsString }

void testSomeRedirect() {

def fc = new FooController() fc.someRedirect() assertEquals "/foo/bar", fc.response.redirectedUrl } }

In the above case the response is an instance of MockHttpServletResponse which we can use to obtain the contentAsString (when writing to the response) or the URL redirected to for example. These mocked versions of the Servlet API are, unlike the real versions, all completely mutable and hence you can set properties on the request such as the contextPath and so on.

Grails does not invoke interceptors or servlet filters automatically when calling actions during integration testing. You should test interceptors and filters in isolation, and via functional testing if necessary.

Testing Controllers with Services

If your controller references a service (or other Spring beans), you have to explicitly initialise the service from your test.

Given a controller using a service:

class FilmStarsController {
    def popularityService

def update = { // do something with popularityService } }

The test for this would be:

class FilmStarsTests extends GroovyTestCase {
    def popularityService

void testInjectedServiceInController () { def fsc = new FilmStarsController() fsc.popularityService = popularityService fsc.update() } }

Testing Controller Command Objects

With command objects you just supply parameters to the request and it will automatically do the command object work for you when you call your action with no parameters:

Given a controller using a command object:

class AuthenticationController {
    def signup = { SignupForm form ->

You can then test it like this:

def controller = new AuthenticationController()
controller.params.login = "marcpalmer"
controller.params.password = "secret"
controller.params.passwordConfirm = "secret"

Grails auto-magically sees your call to signup() as a call to the action and populates the command object from the mocked request parameters. During controller testing, the params are mutable with a mocked request supplied by Grails.

Testing Controllers and the render Method

The render method allows you to render a custom view at any point within the body of an action. For instance, consider the example below:

def save = {
    def book = Book(params)
    if (book.save()) {
        // handle
    else {
        render(view:"create", model:[book:book])

In the above example the result of the model of the action is not available as the return value, but instead is stored within the modelAndView property of the controller. The modelAndView property is an instance of Spring MVC's ModelAndView class and you can use it to the test the result of an action:

def bookController = new BookController()
def model = bookController.modelAndView.model.book

Simulating Request Data

If you're testing an action that requires request data such as a REST web service you can use the Spring MockHttpServletRequest object to do so. For example consider this action which performs data binding from an incoming request:

def create = {
    [book: new Book(params['book']) ]

If you wish the simulate the 'book' parameter as an XML request you could do something like the following:

void testCreateWithXML() {
    def controller = new BookController()
    controller.request.contentType = 'text/xml'
    controller.request.content = '''\
            <?xml version="1.0" encoding="ISO-8859-1"?>
                <title>The Stand</title>
            '''.stripIndent().getBytes() // note we need the bytes

def model = controller.create() assert model.book assertEquals "The Stand", model.book.title }

The same can be achieved with a JSON request:

void testCreateWithJSON() {
    def controller = new BookController()
    controller.request.contentType = "text/json"
    controller.request.content =
            '{"id":1,"class":"Book","title":"The Stand"}'.getBytes()

def model = controller.create() assert model.book assertEquals "The Stand", model.book.title }

With JSON don't forget the class property to specify the name the target type to bind too. In the XML this is implicit within the name of the <book> node, but with JSON you need this property as part of the JSON packet.

For more information on the subject of REST web services see the section on REST.

Testing Web Flows

Testing Web Flows requires a special test harness called grails.test.WebFlowTestCase which sub classes Spring Web Flow's AbstractFlowExecutionTests class.

Subclasses of WebFlowTestCase must be integration tests

For example given this trivial flow:

class ExampleController {
    def exampleFlow = {
        start {
            on("go") {
                flow.hello = "world"
            }.to "next"
        next {
            on("back").to "start"
            on("go").to "subber"
        subber {
            subflow(action: "sub")

def subFlow = { subSubflowState { subflow(controller: "other", action: "otherSub") on("next").to("next") } … } }

You need to tell the test harness what to use for the "flow definition". This is done via overriding the abstract getFlow method:

class ExampleFlowTests extends grails.test.WebFlowTestCase {
    def getFlow() { new ExampleController().exampleFlow }

If you need to specify the flow id you can do so by overriding the getFlowId method otherwise the default is test:

class ExampleFlowTests extends grails.test.WebFlowTestCase {
    String getFlowId() { "example" }

If the flow under test calls any subflows, these (or mocks) need to be registered before the calling flow :

protected void setUp() {
    registerFlow("other/otherSub") { // register a simplified mock
        start {

// register the original subflow registerFlow("example/sub", new ExampleController().subFlow) }

Once this is done in your test you need to kick off the flow with the startFlow method:

void testExampleFlow() {
    def viewSelection = startFlow()

To trigger and event you need to use the signalEvent method:

void testExampleFlow() {
    assert "next" == flowExecution.activeSession.state.id
    assert "world" == flowScope.hello

Here we have signaled to the flow to execute the event "go" this causes a transition to the "next" state. In the example a transition action placed a hello variable into the flow scope.

Testing Tag Libraries

Testing tag libraries is actually pretty trivial because when a tag is invoked as a method it returns its result as a string. So for example if you have a tag library like this:

class FooTagLib {
   def bar =  { attrs, body ->
          out << "<p>Hello World!</p>"

def bodyTag = { attrs, body -> out << "<${attrs.name}>" out << body() out << "</${attrs.name}>" } }

The tests would look like:

class FooTagLibTests extends GroovyTestCase {

void testBarTag() { assertEquals "<p>Hello World!</p>", new FooTagLib().bar(null,null).toString() }

void testBodyTag() { assertEquals "<p>Hello World!</p>", new FooTagLib().bodyTag(name:"p") { "Hello World!" }.toString() } }

Notice that for the second example, testBodyTag, we pass a block that returns the body of the tag. This is handy for representing the body as a String.

Testing Tag Libraries with GroovyPagesTestCase

In addition to doing simply testing of tag libraries like the above you can also use the grails.test.GroovyPagesTestCase class to test tag libraries.

The GroovyPagesTestCase class is a sub class of the regular GroovyTestCase class and provides utility methods for testing the output of a GSP rendering.

GroovyPagesTestCase can only be used in an integration test.

As an example given a date formatting tag library such as the one below:

class FormatTagLib {
    def dateFormat = { attrs, body ->
        out << new java.text.SimpleDateFormat(attrs.format) << attrs.date

This can be easily tested as follows:

class FormatTagLibTests extends GroovyPagesTestCase {
    void testDateFormat() {
        def template =
                '<g:dateFormat format="dd-MM-yyyy" date="${myDate}" />'

def testDate = … // create the date assertOutputEquals( '01-01-2008', template, [myDate:testDate] ) } }

You can also obtain the result of a GSP using the applyTemplate method of the GroovyPagesTestCase class:

class FormatTagLibTests extends GroovyPagesTestCase {
    void testDateFormat() {
        def template =
                '<g:dateFormat format="dd-MM-yyyy" date="${myDate}" />'

def testDate = … // create the date def result = applyTemplate( template, [myDate:testDate] )

assertEquals '01-01-2008', result } }

Testing Domain Classes

Testing domain classes is typically a simple matter of using the GORM API, however there are some things to be aware of. Firstly, if you are testing queries you will often need to "flush" in order to ensure the correct state has been persisted to the database. For example take the following example:

void testQuery() {
    def books = [
            new Book(title:"The Stand"),
            new Book(title:"The Shining")]

assertEquals 2, Book.list().size() }

This test will actually fail, because calling save does not actually persist the Book instances when called. Calling save merely indicates to Hibernate that at some point in the future these instances should be persisted. If you wish to commit changes immediately you need to "flush" them:

void testQuery() {
    def books = [
            new Book(title:"The Stand"),
            new Book(title:"The Shining")]

assertEquals 2, Book.list().size() }

In this case since we're passing the argument flush with a value of true the updates will be persisted immediately and hence will be available to the query later on.

9.3 Functional Testing

Functional tests involve making HTTP requests against the running application and verifying the resultant behaviour. Grails does not ship with any support for writing functional tests directly, but there are several plugins available for this.

Consult the documentation for each plugin for it's capabilities.

Common Options

There are options that are common to all plugins that control how the Grails application is launched, if at all.


The -inline option specifies that the grails application should be started inline (i.e. like run-app).

This option is implicitly set unless the baseUrl or war options are set


The -war option specifies that the grails application should be packaged as a war and started. This is useful as it tests your application in a production like state, but it has a longer startup time than the -inline option. It also runs the war in a forked JVM, meaning that you cannot access any internal application objects.

grails test-app functional: -war

Note that the same build/config options for the run-war command apply to functional testing against the WAR.


The -https option results in the application being able to receive https requests as well as http requests. It is compatible with both the -inline and -war options.

grails test-app functional: -https

Note that this does not change the test base url to be https, it will still be http unless the -httpsBaseUrl option is also given.


The -httpsBaseUrl causes the implicit base url to be used for tests to be a https url.

grails test-app functional: -httpsBaseUrl

This option is ignored if the -baseUrl option is given.


The baseUrl option allows the base url for tests to be specified.

grails test-app functional: -baseUrl=http://mycompany.com/grailsapp

This option will prevent the local grails application being started unless -inline or -war are given as well. If you want to use a custom base url, but still want to test against the local Grails application you must specify one of either the -inline or -war options.