Implémentation C # de la comparaison d'objets profonds/récursifs dans .net 3.5
Je recherche une implémentation récursive ou profonde d'objets spécifique à C #, open source (ou code source disponible).
Je cherche actuellement à comparer deux graphiques d'objets vivants, le résultat de cette comparaison étant un ensemble de divergences dans les graphiques. Les objets sont des instanciations d'un ensemble de classes connues au moment de l'exécution (mais pas nécessairement au moment de la compilation).
Il est spécifiquement nécessaire de pouvoir mapper les divergences dans les graphiques vers les objets contenant les divergences.
J'ai trouvé une application vraiment agréable et gratuite sur www.kellermansoftware.com intitulée Compare .NET Objects qui peut être trouvée ici . Hautement recommandé.
Semble avoir déménagé sur github - la version la plus récente est disponible ici
C'est un domaine complexe. J'ai fait des choses comme ça au moment de l'exécution, et ça devient vite compliqué. Si possible, vous constaterez peut-être que le moyen le plus simple de procéder consiste à sérialiser les objets et à comparer le formulaire sérialisé (peut-être xml-diff et XmlSerializer). Ceci est compliqué un petit du fait que les types ne sont pas connus avant l'exécution, mais pas énormément (vous pouvez toujours utiliser new XmlSerializer(obj.GetType()) etc.).
Ce serait mon approche default, de toute façon.
Voici une contrainte personnalisée NUnit 2.4.6 que nous utilisons pour comparer des graphiques complexes. Il prend en charge les collections incorporées, les références parent, la définition de la tolérance pour les comparaisons numériques, l'identification des noms de champs à ignorer (même au plus profond de la hiérarchie) et les types de décoration à toujours ignorer.
Je suis sûr que ce code peut être adapté pour être utilisé en dehors de NUnit, le gros du code ne dépend pas de NUnit.
Nous l'utilisons dans des milliers de tests unitaires.
using System;
using System.Collections;
using System.Collections.Generic;
using System.Reflection;
using System.Text;
using NUnit.Framework;
using NUnit.Framework.Constraints;
namespace Tests
{
public class ContentsEqualConstraint : Constraint
{
private readonly object expected;
private Constraint failedEquality;
private string expectedDescription;
private string actualDescription;
private readonly Stack<string> typePath = new Stack<string>();
private string typePathExpanded;
private readonly HashSet<string> _ignoredNames = new HashSet<string>();
private readonly HashSet<Type> _ignoredTypes = new HashSet<Type>();
private readonly LinkedList<Type> _ignoredInterfaces = new LinkedList<Type>();
private readonly LinkedList<string> _ignoredSuffixes = new LinkedList<string>();
private readonly IDictionary<Type, Func<object, object, bool>> _predicates = new Dictionary<Type, Func<object, object, bool>>();
private bool _withoutSort;
private int _maxRecursion = int.MaxValue;
private readonly HashSet<VisitedComparison> _visitedObjects = new HashSet<VisitedComparison>();
private static readonly HashSet<string> _globallyIgnoredNames = new HashSet<string>();
private static readonly HashSet<Type> _globallyIgnoredTypes = new HashSet<Type>();
private static readonly LinkedList<Type> _globallyIgnoredInterfaces = new LinkedList<Type>();
private static object _regionalTolerance;
public ContentsEqualConstraint(object expectedValue)
{
expected = expectedValue;
}
public ContentsEqualConstraint Comparing<T>(Func<T, T, bool> predicate)
{
Type t = typeof (T);
if (predicate == null)
{
_predicates.Remove(t);
}
else
{
_predicates[t] = (x, y) => predicate((T) x, (T) y);
}
return this;
}
public ContentsEqualConstraint Ignoring(string fieldName)
{
_ignoredNames.Add(fieldName);
return this;
}
public ContentsEqualConstraint Ignoring(Type fieldType)
{
if (fieldType.IsInterface)
{
_ignoredInterfaces.AddFirst(fieldType);
}
else
{
_ignoredTypes.Add(fieldType);
}
return this;
}
public ContentsEqualConstraint IgnoringSuffix(string suffix)
{
if (string.IsNullOrEmpty(suffix))
{
throw new ArgumentNullException("suffix");
}
_ignoredSuffixes.AddLast(suffix);
return this;
}
public ContentsEqualConstraint WithoutSort()
{
_withoutSort = true;
return this;
}
public ContentsEqualConstraint RecursingOnly(int levels)
{
_maxRecursion = levels;
return this;
}
public static void GlobalIgnore(string fieldName)
{
_globallyIgnoredNames.Add(fieldName);
}
public static void GlobalIgnore(Type fieldType)
{
if (fieldType.IsInterface)
{
_globallyIgnoredInterfaces.AddFirst(fieldType);
}
else
{
_globallyIgnoredTypes.Add(fieldType);
}
}
public static IDisposable RegionalIgnore(string fieldName)
{
return new RegionalIgnoreTracker(fieldName);
}
public static IDisposable RegionalIgnore(Type fieldType)
{
return new RegionalIgnoreTracker(fieldType);
}
public static IDisposable RegionalWithin(object tolerance)
{
return new RegionalWithinTracker(tolerance);
}
public override bool Matches(object actualValue)
{
typePathExpanded = null;
actual = actualValue;
return Matches(expected, actualValue);
}
private bool Matches(object expectedValue, object actualValue)
{
bool matches = true;
if (!MatchesNull(expectedValue, actualValue, ref matches))
{
return matches;
}
// DatesEqualConstraint supports tolerance in dates but works as equal constraint for everything else
Constraint eq = new DatesEqualConstraint(expectedValue).Within(tolerance ?? _regionalTolerance);
if (eq.Matches(actualValue))
{
return true;
}
if (MatchesVisited(expectedValue, actualValue, ref matches))
{
if (MatchesDictionary(expectedValue, actualValue, ref matches) &&
MatchesList(expectedValue, actualValue, ref matches) &&
MatchesType(expectedValue, actualValue, ref matches) &&
MatchesPredicate(expectedValue, actualValue, ref matches))
{
MatchesFields(expectedValue, actualValue, eq, ref matches);
}
}
return matches;
}
private bool MatchesNull(object expectedValue, object actualValue, ref bool matches)
{
if (IsNullEquivalent(expectedValue))
{
expectedValue = null;
}
if (IsNullEquivalent(actualValue))
{
actualValue = null;
}
if (expectedValue == null && actualValue == null)
{
matches = true;
return false;
}
if (expectedValue == null)
{
expectedDescription = "null";
actualDescription = "NOT null";
matches = Failure;
return false;
}
if (actualValue == null)
{
expectedDescription = "not null";
actualDescription = "null";
matches = Failure;
return false;
}
return true;
}
private bool MatchesType(object expectedValue, object actualValue, ref bool matches)
{
Type expectedType = expectedValue.GetType();
Type actualType = actualValue.GetType();
if (expectedType != actualType)
{
try
{
Convert.ChangeType(actualValue, expectedType);
}
catch(InvalidCastException)
{
expectedDescription = expectedType.FullName;
actualDescription = actualType.FullName;
matches = Failure;
return false;
}
}
return true;
}
private bool MatchesPredicate(object expectedValue, object actualValue, ref bool matches)
{
Type t = expectedValue.GetType();
Func<object, object, bool> predicate;
if (_predicates.TryGetValue(t, out predicate))
{
matches = predicate(expectedValue, actualValue);
return false;
}
return true;
}
private bool MatchesVisited(object expectedValue, object actualValue, ref bool matches)
{
var c = new VisitedComparison(expectedValue, actualValue);
if (_visitedObjects.Contains(c))
{
matches = true;
return false;
}
_visitedObjects.Add(c);
return true;
}
private bool MatchesDictionary(object expectedValue, object actualValue, ref bool matches)
{
if (expectedValue is IDictionary && actualValue is IDictionary)
{
var expectedDictionary = (IDictionary)expectedValue;
var actualDictionary = (IDictionary)actualValue;
if (expectedDictionary.Count != actualDictionary.Count)
{
expectedDescription = expectedDictionary.Count + " item dictionary";
actualDescription = actualDictionary.Count + " item dictionary";
matches = Failure;
return false;
}
foreach (DictionaryEntry expectedEntry in expectedDictionary)
{
if (!actualDictionary.Contains(expectedEntry.Key))
{
expectedDescription = expectedEntry.Key + " exists";
actualDescription = expectedEntry.Key + " does not exist";
matches = Failure;
return false;
}
if (CanRecurseFurther)
{
typePath.Push(expectedEntry.Key.ToString());
if (!Matches(expectedEntry.Value, actualDictionary[expectedEntry.Key]))
{
matches = Failure;
return false;
}
typePath.Pop();
}
}
matches = true;
return false;
}
return true;
}
private bool MatchesList(object expectedValue, object actualValue, ref bool matches)
{
if (!(expectedValue is IList && actualValue is IList))
{
return true;
}
var expectedList = (IList) expectedValue;
var actualList = (IList) actualValue;
if (!Matches(expectedList.Count, actualList.Count))
{
matches = false;
}
else
{
if (CanRecurseFurther)
{
int max = expectedList.Count;
if (max != 0 && !_withoutSort)
{
SafeSort(expectedList);
SafeSort(actualList);
}
for (int i = 0; i < max; i++)
{
typePath.Push(i.ToString());
if (!Matches(expectedList[i], actualList[i]))
{
matches = false;
return false;
}
typePath.Pop();
}
}
matches = true;
}
return false;
}
private void MatchesFields(object expectedValue, object actualValue, Constraint equalConstraint, ref bool matches)
{
Type expectedType = expectedValue.GetType();
FieldInfo[] fields = expectedType.GetFields(BindingFlags.Instance | BindingFlags.NonPublic);
// should have passed the EqualConstraint check
if (expectedType.IsPrimitive ||
expectedType == typeof(string) ||
expectedType == typeof(Guid) ||
fields.Length == 0)
{
failedEquality = equalConstraint;
matches = Failure;
return;
}
if (expectedType == typeof(DateTime))
{
var expectedDate = (DateTime)expectedValue;
var actualDate = (DateTime)actualValue;
if (Math.Abs((expectedDate - actualDate).TotalSeconds) > 3.0)
{
failedEquality = equalConstraint;
matches = Failure;
return;
}
matches = true;
return;
}
if (CanRecurseFurther)
{
while(true)
{
foreach (FieldInfo field in fields)
{
if (!Ignore(field))
{
typePath.Push(field.Name);
if (!Matches(GetValue(field, expectedValue), GetValue(field, actualValue)))
{
matches = Failure;
return;
}
typePath.Pop();
}
}
expectedType = expectedType.BaseType;
if (expectedType == null)
{
break;
}
fields = expectedType.GetFields(BindingFlags.Instance | BindingFlags.NonPublic);
}
}
matches = true;
return;
}
private bool Ignore(FieldInfo field)
{
if (_ignoredNames.Contains(field.Name) ||
_ignoredTypes.Contains(field.FieldType) ||
_globallyIgnoredNames.Contains(field.Name) ||
_globallyIgnoredTypes.Contains(field.FieldType) ||
field.GetCustomAttributes(typeof (IgnoreContentsAttribute), false).Length != 0)
{
return true;
}
foreach(string ignoreSuffix in _ignoredSuffixes)
{
if (field.Name.EndsWith(ignoreSuffix))
{
return true;
}
}
foreach (Type ignoredInterface in _ignoredInterfaces)
{
if (ignoredInterface.IsAssignableFrom(field.FieldType))
{
return true;
}
}
return false;
}
private static bool Failure
{
get
{
return false;
}
}
private static bool IsNullEquivalent(object value)
{
return value == null ||
value == DBNull.Value ||
(value is int && (int) value == int.MinValue) ||
(value is double && (double) value == double.MinValue) ||
(value is DateTime && (DateTime) value == DateTime.MinValue) ||
(value is Guid && (Guid) value == Guid.Empty) ||
(value is IList && ((IList)value).Count == 0);
}
private static object GetValue(FieldInfo field, object source)
{
try
{
return field.GetValue(source);
}
catch(Exception ex)
{
return ex;
}
}
public override void WriteMessageTo(MessageWriter writer)
{
if (TypePath.Length != 0)
{
writer.WriteLine("Failure on " + TypePath);
}
if (failedEquality != null)
{
failedEquality.WriteMessageTo(writer);
}
else
{
base.WriteMessageTo(writer);
}
}
public override void WriteDescriptionTo(MessageWriter writer)
{
writer.Write(expectedDescription);
}
public override void WriteActualValueTo(MessageWriter writer)
{
writer.Write(actualDescription);
}
private string TypePath
{
get
{
if (typePathExpanded == null)
{
string[] p = typePath.ToArray();
Array.Reverse(p);
var text = new StringBuilder(128);
bool isFirst = true;
foreach(string part in p)
{
if (isFirst)
{
text.Append(part);
isFirst = false;
}
else
{
int i;
if (int.TryParse(part, out i))
{
text.Append("[" + part + "]");
}
else
{
text.Append("." + part);
}
}
}
typePathExpanded = text.ToString();
}
return typePathExpanded;
}
}
private bool CanRecurseFurther
{
get
{
return typePath.Count < _maxRecursion;
}
}
private static bool SafeSort(IList list)
{
if (list == null)
{
return false;
}
if (list.Count < 2)
{
return true;
}
try
{
object first = FirstNonNull(list) as IComparable;
if (first == null)
{
return false;
}
if (list is Array)
{
Array.Sort((Array)list);
return true;
}
return CallIfExists(list, "Sort");
}
catch
{
return false;
}
}
private static object FirstNonNull(IEnumerable enumerable)
{
if (enumerable == null)
{
throw new ArgumentNullException("enumerable");
}
foreach (object item in enumerable)
{
if (item != null)
{
return item;
}
}
return null;
}
private static bool CallIfExists(object instance, string method)
{
if (instance == null)
{
throw new ArgumentNullException("instance");
}
if (String.IsNullOrEmpty(method))
{
throw new ArgumentNullException("method");
}
Type target = instance.GetType();
MethodInfo m = target.GetMethod(method, new Type[0]);
if (m != null)
{
m.Invoke(instance, null);
return true;
}
return false;
}
#region VisitedComparison Helper
private class VisitedComparison
{
private readonly object _expected;
private readonly object _actual;
public VisitedComparison(object expected, object actual)
{
_expected = expected;
_actual = actual;
}
public override int GetHashCode()
{
return GetHashCode(_expected) ^ GetHashCode(_actual);
}
private static int GetHashCode(object o)
{
if (o == null)
{
return 0;
}
return o.GetHashCode();
}
public override bool Equals(object obj)
{
if (obj == null)
{
return false;
}
if (obj.GetType() != typeof(VisitedComparison))
{
return false;
}
var other = (VisitedComparison) obj;
return _expected == other._expected &&
_actual == other._actual;
}
}
#endregion
#region RegionalIgnoreTracker Helper
private class RegionalIgnoreTracker : IDisposable
{
private readonly string _fieldName;
private readonly Type _fieldType;
public RegionalIgnoreTracker(string fieldName)
{
if (!_globallyIgnoredNames.Add(fieldName))
{
_globallyIgnoredNames.Add(fieldName);
_fieldName = fieldName;
}
}
public RegionalIgnoreTracker(Type fieldType)
{
if (!_globallyIgnoredTypes.Add(fieldType))
{
_globallyIgnoredTypes.Add(fieldType);
_fieldType = fieldType;
}
}
public void Dispose()
{
if (_fieldName != null)
{
_globallyIgnoredNames.Remove(_fieldName);
}
if (_fieldType != null)
{
_globallyIgnoredTypes.Remove(_fieldType);
}
}
}
#endregion
#region RegionalWithinTracker Helper
private class RegionalWithinTracker : IDisposable
{
public RegionalWithinTracker(object tolerance)
{
_regionalTolerance = tolerance;
}
public void Dispose()
{
_regionalTolerance = null;
}
}
#endregion
#region IgnoreContentsAttribute
[AttributeUsage(AttributeTargets.Field)]
public sealed class IgnoreContentsAttribute : Attribute
{
}
#endregion
}
public class DatesEqualConstraint : EqualConstraint
{
private readonly object _expected;
public DatesEqualConstraint(object expectedValue) : base(expectedValue)
{
_expected = expectedValue;
}
public override bool Matches(object actualValue)
{
if (tolerance != null && tolerance is TimeSpan)
{
if (_expected is DateTime && actualValue is DateTime)
{
var expectedDate = (DateTime) _expected;
var actualDate = (DateTime) actualValue;
var toleranceSpan = (TimeSpan) tolerance;
if ((actualDate - expectedDate).Duration() <= toleranceSpan)
{
return true;
}
}
tolerance = null;
}
return base.Matches(actualValue);
}
}
}
C'est en fait un processus simple. En utilisant la réflexion, vous pouvez comparer chaque champ de l’objet.
public static Boolean ObjectMatches(Object x, Object y)
{
if (x == null && y == null)
return true;
else if ((x == null && y != null) || (x != null && y == null))
return false;
Type tx = x.GetType();
Type ty = y.GetType();
if (tx != ty)
return false;
foreach(FieldInfo field in tx.GetFields(BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance | BindingFlags.DeclaredOnly))
{
if (field.FieldType.IsValueType && (field.GetValue(x).ToString() != field.GetValue(y).ToString()))
return false;
else if (field.FieldType.IsClass && !ObjectMatches(field.GetValue(x), field.GetValue(y)))
return false;
}
return true;
}
En utilisant le Nuget suggéré par Jesse et ce code, j'ai réussi à comparer deux objets avec d'excellents résultats.
using KellermanSoftware.CompareNetObjects;
using System;
namespace MyProgram.UnitTestHelper
{
public class ObjectComparer
{
public static bool ObjectsHaveSameValues(object first, object second)
{
CompareLogic cl = new CompareLogic();
ComparisonResult result = cl.Compare(first, second);
if (!result.AreEqual)
Console.WriteLine(result.DifferencesString);
return result.AreEqual;
}
}
}
Voici un simple comparateur que nous avons utilisé avec les tests unitaires pour affirmer que deux objets ont des propriétés égales. C'est un mélange d'idées trouvées dans divers articles et de références circulaires.
public static class TestHelper
{
public static void AssertAreEqual(Object expected, Object actual, String name)
{
// Start a new check with an empty list of actual objects checked
// The list of actual objects checked is used to ensure that circular references don't result in infinite recursion
List<Object> actualObjectsChecked = new List<Object>();
AssertAreEqual(expected, actual, name, actualObjectsChecked);
}
private static void AssertAreEqual(Object expected, Object actual, String name, List<Object> actualObjectsChecked)
{
// Just return if already checked the actual object
if (actualObjectsChecked.Contains(actual))
{
return;
}
actualObjectsChecked.Add(actual);
// If both expected and actual are null, they are considered equal
if (expected == null && actual == null)
{
return;
}
if (expected == null && actual != null)
{
Assert.Fail(String.Format("The actual value of {0} was not null when null was expected.", name));
}
if (expected != null && actual == null)
{
Assert.Fail(String.Format("The actual value of {0} was null when an instance was expected.", name));
}
// Get / check type info
// Note: GetType always returns instantiated (i.e. most derived) type
Type expectedType = expected.GetType();
Type actualType = actual.GetType();
if (expectedType != actualType)
{
Assert.Fail(String.Format("The actual type of {0} was not the same as the expected type.", name));
}
// If expected is a Primitive, Value, or IEquatable type, assume Equals is sufficient to check
// Note: Every IEquatable type should have also overridden Object.Equals
if (expectedType.IsPrimitive || expectedType.IsValueType || expectedType.IsIEquatable())
{
Assert.IsTrue(expected.Equals(actual), "The actual {0} is not equal to the expected.", name);
return;
}
// If expected is an IEnumerable type, assume comparing enumerated items is sufficient to check
IEnumerable<Object> expectedEnumerable = expected as IEnumerable<Object>;
IEnumerable<Object> actualEnumerable = actual as IEnumerable<Object>;
if ((expectedEnumerable != null) && (actualEnumerable != null))
{
Int32 actualEnumerableCount = actualEnumerable.Count();
Int32 expectedEnumerableCount = expectedEnumerable.Count();
// Check size first
if (actualEnumerableCount != expectedEnumerableCount)
{
Assert.Fail(String.Format("The actual number of enumerable items in {0} did not match the expected number.", name));
}
// Check items in order, assuming order is the same
for (int i = 0; i < actualEnumerableCount; ++i)
{
AssertAreEqual(expectedEnumerable.ElementAt(i), actualEnumerable.ElementAt(i), String.Format("{0}[{1}]", name, i), actualObjectsChecked);
}
return;
}
// If expected is not a Primitive, Value, IEquatable, or Ienumerable type, assume comparing properties is sufficient to check
// Iterate through properties
foreach (PropertyInfo propertyInfo in actualType.GetProperties(BindingFlags.Instance | BindingFlags.Public))
{
// Skip properties that can't be read or require parameters
if ((!propertyInfo.CanRead) || (propertyInfo.GetIndexParameters().Length != 0))
{
continue;
}
// Get properties from both
Object actualProperty = propertyInfo.GetValue(actual, null);
Object expectedProperty = propertyInfo.GetValue(expected, null);
AssertAreEqual(expectedProperty, actualProperty, String.Format("{0}.{1}", name, propertyInfo.Name), actualObjectsChecked);
}
}
public static Boolean IsIEquatable(this Type type)
{
return type.GetInterfaces().Any(x => x.IsGenericType && x.GetGenericTypeDefinition() == typeof(IEquatable<>));
}
}