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Groovy example source code file (StubFor.groovy)

This example Groovy source code file (StubFor.groovy) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Groovy tags/keywords

closure, closure, demand, demand, groovy, groovyobject, groovyobject, ignore, looseexpectation, mockinterceptor, mockproxymetaclass, regex, string, stubfor, stubfor

The Groovy StubFor.groovy source code

/*
 * Copyright 2003-2010 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package groovy.mock.interceptor

import java.util.regex.Pattern

/**
 * StubFor supports (typically unit) testing of classes in isolation by allowing
 * a loosely-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 stub objects to help isolate out
 * the logic in the CUT. StubFor allows such stubs to be created using
 * meta-programming. The desired behavior of collaborators is defined as a
 * behavior specification. The behavior can be checked by the user using verify().
 * With StubFor, a stub's expectation is sequence independent and use of verify()
 * is left to the user.
 *
 * Typical usage is as follows:
 * <pre>
 * import groovy.mock.interceptor.StubFor
 *
 * class Person {
 *   String first, last
 * }
 *
 * class Family {
 *   Person mother, father
 *   def nameOfFather() { "$father.first $father.last" }
 * }
 *
 * def stub = new StubFor(Person)
 * stub.demand.with {
 *   getLast{ 'name' }
 *   getFirst{ 'dummy' }
 * }
 * stub.use {
 *   def john = new Person(first:'John', last:'Smith')
 *   def f = new Family(father:john)
 *   assert f.nameOfFather() == 'dummy name'
 * }
 * stub.expect.verify()
 * </pre>
 * Here, <code>Family is our class under test and Person is the collaborator.
 * We are using normal Groovy property semantics here; hence the statement
 * <code>father.first causes a call to father.getFirst() to occur.
 *
 * For a complete list of features, see: {@link MockFor}.
 *
 * @author Dierk Koenig
 * @author Paul King
 */
class StubFor {

    MockProxyMetaClass proxy
    Demand demand
    Ignore ignore
    def expect
    Map instanceExpectations = [:]
    Class clazz

    StubFor(Class clazz, boolean interceptConstruction = false) {
        if (interceptConstruction && !GroovyObject.isAssignableFrom(clazz)) {
            throw new IllegalArgumentException("StubFor with constructor interception enabled is only allowed for Groovy objects but found: " + clazz.name)
        }
        this.clazz = clazz
        proxy = MockProxyMetaClass.make(clazz, interceptConstruction)
        demand = new Demand()
        ignore = new Ignore(parent:this)
        expect = new LooseExpectation(demand)
        proxy.interceptor = new MockInterceptor(expectation: expect)
    }

    /**
     * @See MockFor#use(Closure)
     */
    void use(Closure closure) {
        proxy.use closure
    }

    void use(GroovyObject obj, Closure closure) {
        proxy.use obj, closure
    }

    /**
     * For manual verification
     */
    void verify(GroovyObject obj) {
        instanceExpectations[obj].verify()
    }

    /**
     * Convenience method
     */
    void verify() {
        expect.verify()
    }

    /**
     * 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 <code>filter object is invoked using the normal Groovy isCase() semantics.
     *
     * @See MockFor#ignore(Object, Closure)
     */
    def ignore(Object filter, Closure filterBehavior = null) {
        // if Stubbing Strings, attempt not to also match Strings with filter
        if (clazz.name == 'java.lang.String' && filter instanceof String) {
            filter = Pattern.compile(filter)
        }
        demand.ignore.put(filter, filterBehavior ?: MockProxyMetaClass.FALL_THROUGH_MARKER)
    }

    /**
     * Allows a more traditional instance-style stubbing paradigm. This is the
     * recommended method to call to use the instance-style with Groovy classes.
     *
     * @See MockFor#proxyInstance(Object)
     */
    GroovyObject proxyInstance(args=null) {
        makeProxyInstance(args, false)
    }

    /**
     * Allows a more traditional instance-style stubbing paradigm. This is the
     * recommended method to call to use the instance-style with Java classes.
     *
     * @See MockFor#proxyDelegateInstance(Object)
     */
    GroovyObject proxyDelegateInstance(args=null) {
        makeProxyInstance(args, true)
    }

    GroovyObject makeProxyInstance(args, boolean isDelegate) {
        def instance = MockFor.getInstance(clazz, args)
        def thisproxy = MockProxyMetaClass.make(isDelegate ? instance.getClass() : clazz)
        def thisdemand = new Demand(recorded: new ArrayList(demand.recorded), ignore: new HashMap(demand.ignore))
        def thisexpect = new LooseExpectation(thisdemand)
        thisproxy.interceptor = new MockInterceptor(expectation: thisexpect)
        instance.metaClass = thisproxy
        def wrapped = instance
        if (isDelegate && clazz.isInterface()) {
            wrapped = ProxyGenerator.INSTANCE.instantiateDelegate([clazz], instance)
        }
        instanceExpectations[wrapped] = thisexpect
        return wrapped
    }

}

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