org.meanbean.test

Class HashCodeMethodTester

java.lang.Object

org.meanbean.test.HashCodeMethodTester

public class HashCodeMethodTester
extends Object

Provides a means of testing the correctness of the hashCode logic implemented by a type, based solely on the provision of the type, with respect to:

• the general hashCode contract

The following is tested:

• that logically equivalent objects have the same hashCode
• the consistent item of the hashCode contract - the hashCode of an object should remain consistent across multiple invocations, so long as the object does not change

Use the tests provided by this class (namely, testHashCode()) to test a class that overrides hashCode() and equals().

As an example, to test the hashCode logic implemented by a class called MyClass do the following:

 HashCodeMethodTester tester = new HashCodeMethodTester();
 tester.testHashCodeMethod(MyClass.class);
 

To test the hashCode logic implemented by a class called MyClass without a no-argument constructor do the following:

 HashCodeMethodTester tester = new HashCodeMethodTester();
 tester.testHashCodeMethod(new Factory<MyClass>() {
        @Override
        public MyClass create() {
                MyClass result = new MyClass("TEST_NAME");
                return result;
        }
 });
 

The Factory creates new logically equivalent instances of MyClass. MyClass has overridden equals() and hashCode(). In the above example, there is only one property, name, which is considered by MyClass's hashCode logic.

Author:

Graham Williamson

Constructor Summary

Constructors

Constructor and Description
HashCodeMethodTester() Prefer BeanVerifier

Method Summary

Modifier and Type	Method and Description
FactoryCollection	getFactoryCollection() Get the collection of test data Factories with which you can register new Factories for custom Data Types.
FactoryLookupStrategy	getFactoryLookupStrategy() Get the FactoryLookupStrategy, which provides a means of acquiring Factories.
RandomValueGenerator	getRandomValueGenerator() Get a RandomValueGenerator.
protected void	testHashCodeConsistent(EquivalentFactory<?> factory) Test that the hashCode logic implemented by the type the specified factory creates is consistent with the consistent item of the hashCode contract.
void	testHashCodeMethod(Class<?> clazz) Test that the hashCode logic implemented by the specified type is correct by testing:
void	testHashCodeMethod(EquivalentFactory<?> factory) Test that the hashCode logic implemented by the type the specified factory creates is correct by testing:
protected void	testHashCodesEqual(EquivalentFactory<?> factory) Test that the hashCode logic implemented by the type the specified factory creates returns equal hashCodes for logically equivalent objects.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

HashCodeMethodTester

public HashCodeMethodTester()

Prefer BeanVerifier

Method Detail

testHashCodeMethod

public void testHashCodeMethod(EquivalentFactory<?> factory)
                        throws IllegalArgumentException,
                               AssertionError

Test that the hashCode logic implemented by the type the specified factory creates is correct by testing:

• that logically equivalent objects have the same hashCode
• the consistent item of the hashCode contract - the hashCode of an object should remain consistent across multiple invocations, so long as the object does not change

If the test fails, an AssertionError is thrown.

Parameters:

factory - An EquivalentFactory that creates non-null logically equivalent objects that will be used to test whether the equals logic implemented by the type is correct. The factory must create logically equivalent but different actual instances of the type upon each invocation of create() in order for the test to be meaningful and correct.

Throws:

IllegalArgumentException - If the specified factory is deemed illegal. For example, if it is null, if it creates a null object or if it creates objects that are not logically equivalent.

AssertionError - If the test fails.

testHashCodeMethod

public void testHashCodeMethod(Class<?> clazz)
                        throws IllegalArgumentException,
                               AssertionError

Test that the hashCode logic implemented by the specified type is correct by testing:

• that logically equivalent objects have the same hashCode
• the consistent item of the hashCode contract - the hashCode of an object should remain consistent across multiple invocations, so long as the object does not change

If the test fails, an AssertionError is thrown.

Parameters:

clazz - The type to test the equals logic of.

Throws:

IllegalArgumentException - If the specified clazz is deemed illegal. For example, if it is null.

AssertionError - If the test fails.

testHashCodesEqual

protected void testHashCodesEqual(EquivalentFactory<?> factory)
                           throws IllegalArgumentException,
                                  AssertionError

Test that the hashCode logic implemented by the type the specified factory creates returns equal hashCodes for logically equivalent objects.

If the test fails, an AssertionError is thrown.

Parameters:

factory - An EquivalentFactory that creates non-null logically equivalent objects that will be used to test whether the hashCode logic implemented by the type returns equal hashCodes for logically equivalent objects. The factory must create logically equivalent but different actual instances of the type upon each invocation of create() in order for the test to be meaningful.

Throws:

IllegalArgumentException - If the specified factory is deemed illegal. For example, if it is null, if it creates a null object or if it creates objects that are not logically equivalent.

AssertionError - If the test fails.

testHashCodeConsistent

protected void testHashCodeConsistent(EquivalentFactory<?> factory)
                               throws IllegalArgumentException,
                                      AssertionError

Test that the hashCode logic implemented by the type the specified factory creates is consistent with the consistent item of the hashCode contract.

If the test fails, an AssertionError is thrown.

Parameters:

factory - An EquivalentFactory that creates non-null logically equivalent objects that will be used to test whether the hashCode logic implemented by the type is consistent with the consistent item of the hashCode contract. The factory must create logically equivalent but different actual instances of the type upon each invocation of create() in order for the test to be meaningful.

Throws:

IllegalArgumentException - If the specified factory is deemed illegal. For example, if it is null or if it creates a null object.

AssertionError - If the test fails.

getRandomValueGenerator

public RandomValueGenerator getRandomValueGenerator()

Get a RandomValueGenerator.

Returns:

A RandomValueGenerator.

getFactoryCollection

public FactoryCollection getFactoryCollection()

Get the collection of test data Factories with which you can register new Factories for custom Data Types.

Returns:

The collection of test data Factories.

getFactoryLookupStrategy

public FactoryLookupStrategy getFactoryLookupStrategy()

Get the FactoryLookupStrategy, which provides a means of acquiring Factories.

Returns:

The factory lookup strategy.