Unit testing: testing service in 3 different ways (part II)

In part I we got acquainted with unit testing of services based on ExpandoMetaClass approach. In this part we will look on a method based on Groovy Mocks. Groovy has excellent built-in support for a range of mocking alternatives. Let's rewrite test from the previous post in order to use Groovy Mocks.

class DocumentServiceTests extends GroovyTestCase {

   def documentService

   void setUp() {
       
       // Initialize the service class, 
       // there is no dynamic injection. 
       documentService = new DocumentService()
   }

   void testSaveDocumentSuccess() {
       // Create the Mock support 
       // for Document class.
       def documentMocker = new MockFor(Document)

       
       // Demand the validate method exactly once,
       // and programming it to return true.
       documentMocker.demand.validate {
           return true
       }

       
       // Demand the save method exactly once,
       // and programming it to return true.
       documentMocker.demand.save {
           return true
       }
           
       // Start using the Mock.
       documentMocker.use {
           documentService.saveDocument(
               new Document(
                   name: "Document name", 
                   description: "Document description",
                   lastModifiedTime: new Date(), 
                   creationTime: new Date(), 
                   revisionCount: 1L, 
                   owner: new User()))
       }
   }

   void testSaveDocumentFailure() {
       
       // Create the Mock support
       // for Document class.
       def documentMocker = new MockFor(Document)

       
       // Demand the validate method exactly once,
       // and programming it to return false.
       documentMocker.demand.validate {
           return false
       }

       // Start using the Mock.
       documentMocker.use {
           // Validation will fail.
           // Expecting exception to be thrown.
           shouldFail(InvalidDocumentException) {
               documentService.saveDocument(
                   new Document(
                       name: "Document name", 
                       description: "Document description",
                       lastModifiedTime: new Date(), 
                       creationTime: new Date(), 
                       revisionCount: 1L))
           }
       }
   }

   void testRetrieveDocumentByIdAndOwnerSuccess() {
       
       // Create the Mock support
       // for Document class.
       def documentMocker = new MockFor(Document)

       
       // Demand the findByIdAndOwner method exactly once,
       // and programming it to return appropriate document.
       documentMocker.demand.findByIdAndOwner { 
           Long id, User owner ->
           return new Document(
               id: id, 
               name: "Document name", 
               description: "Document description",
               lastModifiedTime: new Date(), 
               creationTime: new Date(), 
               revisionCount: 1L, 
               owner: owner)
       }

       
       // Demand the getName method exactly once,
       // and programming it to return appropriate name.
       // Needed for assertion.
       documentMocker.demand.getName {
           return "Document name"
       }
 
       
       // Demand the getDescription method exactly once,
       // and programming it to return appropriate name.
       // Needed for assertion.
       documentMocker.demand.getDescription {
           return "Document description"
       }

       
       // Demand the getRevisionCount method exactly once,
       // and programming it to return appropriate name.
       // Needed for assertion.
       documentMocker.demand.getRevisionCount {
           return 1L
       }

       // Start using the Mock.
       documentMocker.use {
           def foundDocument = 
                documentService.retrieveDocumentByIdAndOwner(
                    1L, new User())

           assertNotNull foundDocument
           assert "Document name" == foundDocument.name
           assert "Document description" == foundDocument.description
           assert 1 == foundDocument.revisionCount
       }
   }

   void testRetrieveDocumentFailure() {
       
       // Create the Mock support
       // for Document class.
       def documentMocker = new MockFor(Document)

       
       // Demand the findByIdAndOwner method exactly once,
       // and programming it to return NULL.
       documentMocker.demand.findByIdAndOwner { Long id, User owner ->
           return null
       }

       // Start using the Mock.
       documentMocker.use {
           // Document will not be found.
           // Exception will be thrown.
           shouldFail(DocumentNotFoundException) {
               documentService.retrieveDocumentByIdAndOwner(
                   1L, new User())
           }
       }
   }

} 

Groovy Mocks have a lot of powerful features, especially You can mock few calls of service method, You can mock not only a tested service but also an injected service, etc. For more detailed information check resources listed below:

1. Using MockFor and StubFor
2. Mocking Static Methods using Groovy
   

In the next post we will rewrite mentioned test using Testing plugin.