MockFor supports (typically unit) testing of classes in isolation by allowing a strictly ordered expectation of the behavior of collaborators to be defined. A typical test scenario involves a class under test (CUT) and one or more collaborators. In such a scenario it is often desirable to just test the business logic of the CUT. One strategy for doing that is to replace the collaborator instances with simplified mock objects to help isolate out the logic in the CUT. MockFor allows such mocks to be created using meta-programming. The desired behavior of collaborators is defined as a behavior specification. The behavior is enforced and checked automatically. With MockFor, a mock's expectation is always sequence dependent and its use automatically ends with a verify(). Typical usage is as follows:
import groovy.mock.interceptor.MockFor class Person { String first, last } class Family { Person father, mother def nameOfMother() { "$mother.first $mother.last" } } def mock = new MockFor(Person) mock.demand.getFirst{ 'dummy' } mock.demand.getLast{ 'name' } mock.use { def mary = new Person(first:'Mary', last:'Smith') def f = new Family(mother:mary) assert f.nameOfMother() == 'dummy name' }Here,
Family
is our class under test and Person
is the collaborator.
We are using normal Groovy property semantics here; hence the statement
mother.last
causes a call to mother.getLast()
to occur.
The following features are supported:
proxyDelegateInstance()
)
proxyInstance()
and proxyDelegateInstance()
ignore
specification on the mock instead of a demand specification
Type | Name and description |
---|---|
static GroovyObject |
getInstance(Class clazz, def args) |
def |
ignore(Object filter, Closure filterBehavior = null) Allows particular method calls to be ignored and not treated as part of the required behavior specification. |
GroovyObject |
makeProxyInstance(def args, boolean isDelegate) |
GroovyObject |
proxyDelegateInstance(def args = null) Allows a more traditional instance-style mocking paradigm. |
GroovyObject |
proxyInstance(def args = null) Allows a more traditional instance-style mocking paradigm. |
void |
use(Closure closure) Identifies the Closure where the mocked collaborator behavior will be applied and verified. |
void |
use(GroovyObject obj, Closure closure) |
void |
verify(GroovyObject obj) If manual verification is required |
The optional interceptConstruction
flag allows mocking of
constructor calls. These are represented in the demand specification
using the class name as this example shows:
import groovy.mock.interceptor.MockFor class Person { String first, last } def interceptConstructorCalls = true def mock = new MockFor(Person, interceptConstructorCalls) def dummy = new Person(first:'Tom', last:'Jones') mock.demand.with { Person() { dummy } // expect constructor call, return dummy getFirst() {'John'} getLast() {'Doe'} } mock.use { def p = new Person(first:'Mary', last:'Smith') assert p.first == 'John' assert p.last == 'Doe' }
Allows particular method calls to be ignored and not treated as part of
the required behavior specification. If you don't specify a return closure
the method call will fall through to the underlying instance, i.e. half-mock style.
The filter
object is invoked using the normal Groovy isCase()
semantics.
Here are some examples:
import groovy.mock.interceptor.MockFor class Person { String first, last def name() { "$first $last" } def ignoreMe() { 'baz' } def ignoreMeToo() { ignoreMe() } def ignoreMeThree() { ignoreMe() } } def mock = new MockFor(Person) mock.ignore(~'get.*') mock.ignore('ignoreMeToo') { 'boo' } mock.ignore(~'ignoreMe.*') mock.demand.name{ 'John' } mock.use { def p = new Person(first:'Mary', last:'Smith') assert p.first == 'Mary' assert p.last == 'Smith' assert p.name() == 'John' assert p.ignoreMe() == 'baz' assert p.ignoreMeToo() == 'boo' assert p.ignoreMeThree() == 'baz' }There is also a convenience form of ignore that matches the same style as demand. E.g. instead of
mock.ignore('hasNext')
you can use
mock.ignore.hasNext()
. A Closure variation is also provided.
This convenience shorthand only applies to the String
form of ignore
and cannot be used with methods from java.lang.Object
.
Be careful using this feature while mocking some of the fundamental Java
classes like String
or Pattern
. As these are used within the
implementation of the ignore capability, strange behavior may be observed.
Allows a more traditional instance-style mocking paradigm. This is the recommended method to call to use the instance-style with Java classes. When mocking interfaces or abstract classes, a compatible proxy instance will be returned. When mocking Java classes, a compatible Groovy class will be generated and proxy instance returned. A MockProxyMetaClass will be instantiated for the class of the instance (i.e. may be on the generated class not the original class).
Allows a more traditional instance-style mocking paradigm. This is the recommended method to call to use the instance-style with Groovy classes. When mocking interfaces or abstract classes, a compatible proxy instance will be returned. When mocking Java classes, a compatible Groovy class will be generated and proxy instance returned. A MockProxyMetaClass will be instantiated for the original class. Typical example:
import groovy.mock.interceptor.MockFor class Person { String first, last } class Family { Person mother, father String nameOfMother() { fullName(mother) } String nameOfFather() { fullName(father) } private fullName(p) { "$p.first $p.last" } } def mock = new MockFor(Person) mock.demand.with { getFirst{ 'dummy' } getLast{ 'name' } } Person john = mock.proxyInstance() Person mary = mock.proxyInstance() Family f = new Family(father:john, mother:mary) assert f.nameOfFather() == 'dummy name' assert f.nameOfMother() == 'dummy name' [john, mary].each{ mock.verify(it) }Normally for mocks,
verify()
is call automatically at the end of the "use" Closure,
but with this style, no "use" Closure is present, so verify()
must be called manually.
Identifies the Closure where the mocked collaborator behavior will be applied and verified.
If manual verification is required
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