org.apache.commons.collections.collection

Class AbstractTestCollection

public abstract class AbstractTestCollection extends AbstractTestObject

Abstract test class for {@link java.util.Collection} methods and contracts.

You should create a concrete subclass of this class to test any custom {@link Collection} implementation. At minimum, you'll have to implement the {@link #makeCollection()} method. You might want to override some of the additional public methods as well:

Element Population Methods

Override these if your collection restricts what kind of elements are allowed (for instance, if null is not permitted):

Supported Operation Methods

Override these if your collection doesn't support certain operations:

Fixture Methods

Fixtures are used to verify that the the operation results in correct state for the collection. Basically, the operation is performed against your collection implementation, and an identical operation is performed against a confirmed collection implementation. A confirmed collection implementation is something like java.util.ArrayList, which is known to conform exactly to its collection interface's contract. After the operation takes place on both your collection implementation and the confirmed collection implementation, the two collections are compared to see if their state is identical. The comparison is usually much more involved than a simple equals test. This verification is used to ensure proper modifications are made along with ensuring that the collection does not change when read-only modifications are made.

The {@link #collection} field holds an instance of your collection implementation; the {@link #confirmed} field holds an instance of the confirmed collection implementation. The {@link #resetEmpty()} and {@link #resetFull()} methods set these fields to empty or full collections, so that tests can proceed from a known state.

After a modification operation to both {@link #collection} and {@link #confirmed}, the {@link #verify()} method is invoked to compare the results. You may want to override {@link #verify()} to perform additional verifications. For instance, when testing the collection views of a map, {@link AbstractTestMap} would override {@link #verify()} to make sure the map is changed after the collection view is changed.

If you're extending this class directly, you will have to provide implementations for the following:

Those methods should provide a confirmed collection implementation that's compatible with your collection implementation.

If you're extending {@link AbstractTestList}, {@link AbstractTestSet}, or {@link AbstractTestBag}, you probably don't have to worry about the above methods, because those three classes already override the methods to provide standard JDK confirmed collections.

Other notes

If your {@link Collection} fails one of these tests by design, you may still use this base set of cases. Simply override the test case (method) your {@link Collection} fails.

Field Summary
Collectioncollection
A collection instance that will be used for testing.
Collectionconfirmed
Confirmed collection.
Constructor Summary
AbstractTestCollection(String testName)
JUnit constructor.
Method Summary
booleanareEqualElementsDistinguishable()
Specifies whether equal elements in the collection are, in fact, distinguishable with information not readily available.
EntrycloneMapEntry(Entry entry)
Creates a new Map Entry that is independent of the first and the map.
Object[]getFullElements()
Returns an array of objects that are contained in a collection produced by {@link #makeFullCollection()}.
Object[]getFullNonNullElements()
Returns a list of elements suitable for return by {@link #getFullElements()}.
Object[]getFullNonNullStringElements()
Returns a list of string elements suitable for return by {@link #getFullElements()}.
Object[]getOtherElements()
Returns an array of elements that are not contained in a full collection.
Object[]getOtherNonNullElements()
Returns the default list of objects returned by {@link #getOtherElements()}.
Object[]getOtherNonNullStringElements()
Returns a list of string elements suitable for return by {@link #getOtherElements()}.
booleanisAddSupported()
Returns true if the collections produced by {@link #makeCollection()} and {@link #makeFullCollection()} support the add and addAll operations.

Default implementation returns true.

booleanisEqualsCheckable()
Returns true to indicate that the collection supports equals() comparisons.
booleanisFailFastSupported()
Returns true to indicate that the collection supports fail fast iterators.
booleanisNullSupported()
Returns true to indicate that the collection supports holding null.
booleanisRemoveSupported()
Returns true if the collections produced by {@link #makeCollection()} and {@link #makeFullCollection()} support the remove, removeAll, retainAll, clear and iterator().remove() methods.
abstract CollectionmakeCollection()
Return a new, empty {@link Collection} to be used for testing.
abstract CollectionmakeConfirmedCollection()
Returns a confirmed empty collection.
abstract CollectionmakeConfirmedFullCollection()
Returns a confirmed full collection.
CollectionmakeFullCollection()
Returns a full collection to be used for testing.
ObjectmakeObject()
Returns an empty collection for Object tests.
voidresetEmpty()
Resets the {@link #collection} and {@link #confirmed} fields to empty collections.
voidresetFull()
Resets the {@link #collection} and {@link #confirmed} fields to full collections.
voidtestCollectionAdd()
Tests {@link Collection#add(Object)}.
voidtestCollectionAddAll()
Tests {@link Collection#addAll(Collection)}.
voidtestCollectionClear()
Test {@link Collection#clear()}.
voidtestCollectionContains()
Tests {@link Collection#contains(Object)}.
voidtestCollectionContainsAll()
Tests {@link Collection#containsAll(Collection)}.
voidtestCollectionIsEmpty()
Tests {@link Collection#isEmpty()}.
voidtestCollectionIterator()
Tests the read-only functionality of {@link Collection#iterator()}.
voidtestCollectionIteratorFailFast()
Tests that the collection's iterator is fail-fast.
voidtestCollectionIteratorRemove()
Tests removals from {@link Collection#iterator()}.
voidtestCollectionRemove()
Tests {@link Collection#remove(Object)}.
voidtestCollectionRemoveAll()
Tests {@link Collection#removeAll(Collection)}.
voidtestCollectionRetainAll()
Tests {@link Collection#retainAll(Collection)}.
voidtestCollectionSize()
Tests {@link Collection#size()}.
voidtestCollectionToArray()
Tests {@link Collection#toArray()}.
voidtestCollectionToArray2()
Tests {@link Collection#toArray(Object[])}.
voidtestCollectionToString()
Tests toString on a collection.
voidtestSerializeDeserializeThenCompare()
voidtestUnsupportedAdd()
If {@link #isAddSupported()} returns false, tests that add operations raise UnsupportedOperationException.
voidtestUnsupportedRemove()
If isRemoveSupported() returns false, tests to see that remove operations raise an UnsupportedOperationException.
voidverify()
Verifies that {@link #collection} and {@link #confirmed} have identical state.

Field Detail

collection

public Collection collection
A collection instance that will be used for testing.

confirmed

public Collection confirmed
Confirmed collection. This is an instance of a collection that is confirmed to conform exactly to the java.util.Collection contract. Modification operations are tested by performing a mod on your collection, performing the exact same mod on an equivalent confirmed collection, and then calling verify() to make sure your collection still matches the confirmed collection.

Constructor Detail

AbstractTestCollection

public AbstractTestCollection(String testName)
JUnit constructor.

Parameters: testName the test class name

Method Detail

areEqualElementsDistinguishable

public boolean areEqualElementsDistinguishable()
Specifies whether equal elements in the collection are, in fact, distinguishable with information not readily available. That is, if a particular value is to be removed from the collection, then there is one and only one value that can be removed, even if there are other elements which are equal to it.

In most collection cases, elements are not distinguishable (equal is equal), thus this method defaults to return false. In some cases, however, they are. For example, the collection returned from the map's values() collection view are backed by the map, so while there may be two values that are equal, their associated keys are not. Since the keys are distinguishable, the values are.

This flag is used to skip some verifications for iterator.remove() where it is impossible to perform an equivalent modification on the confirmed collection because it is not possible to determine which value in the confirmed collection to actually remove. Tests that override the default (i.e. where equal elements are distinguishable), should provide additional tests on iterator.remove() to make sure the proper elements are removed when remove() is called on the iterator.

cloneMapEntry

public Entry cloneMapEntry(Entry entry)
Creates a new Map Entry that is independent of the first and the map.

getFullElements

public Object[] getFullElements()
Returns an array of objects that are contained in a collection produced by {@link #makeFullCollection()}. Every element in the returned array must be an element in a full collection.

The default implementation returns a heterogenous array of objects with some duplicates. null is added if allowed. Override if you require specific testing elements. Note that if you override {@link #makeFullCollection()}, you must override this method to reflect the contents of a full collection.

getFullNonNullElements

public Object[] getFullNonNullElements()
Returns a list of elements suitable for return by {@link #getFullElements()}. The array returned by this method does not include null, but does include a variety of objects of different types. Override getFullElements to return the results of this method if your collection does not support the null element.

getFullNonNullStringElements

public Object[] getFullNonNullStringElements()
Returns a list of string elements suitable for return by {@link #getFullElements()}. Override getFullElements to return the results of this method if your collection does not support heterogenous elements or the null element.

getOtherElements

public Object[] getOtherElements()
Returns an array of elements that are not contained in a full collection. Every element in the returned array must not exist in a collection returned by {@link #makeFullCollection()}. The default implementation returns a heterogenous array of elements without null. Note that some of the tests add these elements to an empty or full collection, so if your collection restricts certain kinds of elements, you should override this method.

getOtherNonNullElements

public Object[] getOtherNonNullElements()
Returns the default list of objects returned by {@link #getOtherElements()}. Includes many objects of different types.

getOtherNonNullStringElements

public Object[] getOtherNonNullStringElements()
Returns a list of string elements suitable for return by {@link #getOtherElements()}. Override getOtherElements to return the results of this method if your collection does not support heterogenous elements or the null element.

isAddSupported

public boolean isAddSupported()
Returns true if the collections produced by {@link #makeCollection()} and {@link #makeFullCollection()} support the add and addAll operations.

Default implementation returns true. Override if your collection class does not support add or addAll.

isEqualsCheckable

public boolean isEqualsCheckable()
Returns true to indicate that the collection supports equals() comparisons. This implementation returns false;

isFailFastSupported

public boolean isFailFastSupported()
Returns true to indicate that the collection supports fail fast iterators. The default implementation returns true;

isNullSupported

public boolean isNullSupported()
Returns true to indicate that the collection supports holding null. The default implementation returns true;

isRemoveSupported

public boolean isRemoveSupported()
Returns true if the collections produced by {@link #makeCollection()} and {@link #makeFullCollection()} support the remove, removeAll, retainAll, clear and iterator().remove() methods. Default implementation returns true. Override if your collection class does not support removal operations.

makeCollection

public abstract Collection makeCollection()
Return a new, empty {@link Collection} to be used for testing.

makeConfirmedCollection

public abstract Collection makeConfirmedCollection()
Returns a confirmed empty collection. For instance, an {@link java.util.ArrayList} for lists or a {@link java.util.HashSet} for sets.

Returns: a confirmed empty collection

makeConfirmedFullCollection

public abstract Collection makeConfirmedFullCollection()
Returns a confirmed full collection. For instance, an {@link java.util.ArrayList} for lists or a {@link java.util.HashSet} for sets. The returned collection should contain the elements returned by {@link #getFullElements()}.

Returns: a confirmed full collection

makeFullCollection

public Collection makeFullCollection()
Returns a full collection to be used for testing. The collection returned by this method should contain every element returned by {@link #getFullElements()}. The default implementation, in fact, simply invokes addAll on an empty collection with the results of {@link #getFullElements()}. Override this default if your collection doesn't support addAll.

makeObject

public Object makeObject()
Returns an empty collection for Object tests.

resetEmpty

public void resetEmpty()
Resets the {@link #collection} and {@link #confirmed} fields to empty collections. Invoke this method before performing a modification test.

resetFull

public void resetFull()
Resets the {@link #collection} and {@link #confirmed} fields to full collections. Invoke this method before performing a modification test.

testCollectionAdd

public void testCollectionAdd()
Tests {@link Collection#add(Object)}.

testCollectionAddAll

public void testCollectionAddAll()
Tests {@link Collection#addAll(Collection)}.

testCollectionClear

public void testCollectionClear()
Test {@link Collection#clear()}.

testCollectionContains

public void testCollectionContains()
Tests {@link Collection#contains(Object)}.

testCollectionContainsAll

public void testCollectionContainsAll()
Tests {@link Collection#containsAll(Collection)}.

testCollectionIsEmpty

public void testCollectionIsEmpty()
Tests {@link Collection#isEmpty()}.

testCollectionIterator

public void testCollectionIterator()
Tests the read-only functionality of {@link Collection#iterator()}.

testCollectionIteratorFailFast

public void testCollectionIteratorFailFast()
Tests that the collection's iterator is fail-fast.

testCollectionIteratorRemove

public void testCollectionIteratorRemove()
Tests removals from {@link Collection#iterator()}.

testCollectionRemove

public void testCollectionRemove()
Tests {@link Collection#remove(Object)}.

testCollectionRemoveAll

public void testCollectionRemoveAll()
Tests {@link Collection#removeAll(Collection)}.

testCollectionRetainAll

public void testCollectionRetainAll()
Tests {@link Collection#retainAll(Collection)}.

testCollectionSize

public void testCollectionSize()
Tests {@link Collection#size()}.

testCollectionToArray

public void testCollectionToArray()
Tests {@link Collection#toArray()}.

testCollectionToArray2

public void testCollectionToArray2()
Tests {@link Collection#toArray(Object[])}.

testCollectionToString

public void testCollectionToString()
Tests toString on a collection.

testSerializeDeserializeThenCompare

public void testSerializeDeserializeThenCompare()

testUnsupportedAdd

public void testUnsupportedAdd()
If {@link #isAddSupported()} returns false, tests that add operations raise UnsupportedOperationException.

testUnsupportedRemove

public void testUnsupportedRemove()
If isRemoveSupported() returns false, tests to see that remove operations raise an UnsupportedOperationException.

verify

public void verify()
Verifies that {@link #collection} and {@link #confirmed} have identical state.
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