我們的代碼庫充滿了具有大量數字和字符串字段的域對象。在我的單元測試中，我發現自己手動創建了這些不同對象的實例，如下所示：var car1 = new Car();car1.Make = "Make1";car1.Model = "Model1";car1.Year = 1;var car2 = new Car();car2.Make = "Make2";car2.Model = "Model2";car2.Year = 2;等等..只用一個函數調用自動構建任何類型的對象的最干凈的方法是什么？請記住，我不希望使用隨機值生成字段。任意可重復值（如上面的 1 和 2）是我想要的。
2 回答
BIG陽
TA貢獻1859條經驗 獲得超6個贊
我最終選擇了一種通用方法，該方法使用反射來自動完成問題顯示的手動完成。以這種方式創建的任何字段都可以被覆蓋，并且必須手動設置任何復雜類型。布爾值只是設置為真。我很想聽聽人們對這樣做的想法。當我構建單元測試時，它為我節省了大量的時間和精力。
這是我的測試最終的外觀（簡單示例，沒有我想用特定值覆蓋的復雜類型或字符串/數字字段，盡管這些也被處理）：
[Test]
public void TestCreateCars()
{
// Arrange
var expectedCars = new List<Car>();
expectedCars.Add(TestUtils.CreateObject<Car>(1));
expectedCars.Add(TestUtils.CreateObject<Car>(2));
expectedCars.Add(TestUtils.CreateObject<Car>(3));
// using moq but anything could be used
_carService.Setup(x => x.GetNewCarsInfo()).Returns(cars);
var carsFactory = new carFactory(_carService);
// Act
var cars = carsFactory.CreateCars();
// Assert
Assert.AreEqual(3, cars.Count);
TestUtils.AssertObjectDefaultFields(cars[0], 1);
TestUtils.AssertObjectDefaultFields(cars[1], 2);
TestUtils.AssertObjectDefaultFields(cars[2], 3);
_carService.VerifyAll();
}
創建對象的方法：
// Use this to instantiate objects of types with a large number of int/string fields for testing. You can override any values after calling this - complex fields won't be set
// -sets numeric values on that object to its 'id'
// -sets string values on that object to the name of the field concatenated with the 'id'
public static T CreateObject<T>(int id)
{
var instance = (T)Activator.CreateInstance(typeof(T));
// only set properties with a visible setter
var properties = typeof(T).GetProperties().Where(prop => prop.GetSetMethod() != null);
foreach (var property in properties)
{
var type = property.PropertyType;
if (IsNumeric(type))
{
type = Nullable.GetUnderlyingType(type) ?? type;
var value = Convert.ChangeType(id, type);
property.SetValue(instance, value);
}
else if (property.PropertyType == typeof(string))
{
property.SetValue(instance, property.Name + id);
}
else if (property.PropertyType == typeof(bool))
{
property.SetValue(instance, true);
}
}
return instance;
}
斷言以這種方式創建的對象的方法具有預期值：
// Use this to assert that an object created by CreateObject<T> has all of the 'default' values:
// -numeric values equal its 'id'
// -string values equal the name of the field concatenated with the 'id'
//
// unsetProperties: property names that we want to assert are their default values
// ignoreProperties: property names that we don't want to assert anything against - we should assert against these outside of this method
public static void AssertObjectDefaultFields<T>(T obj, int id, HashSet<string> unsetProperties = null, HashSet<string> ignoreProperties = null)
{
// only test properties with a visible setter, otherwise it wouldnt have been set
var properties = typeof(T).GetProperties().Where(prop => prop.GetSetMethod() != null);
unsetProperties = unsetProperties ?? new HashSet<String>();
ignoreProperties = ignoreProperties ?? new HashSet<String>();
foreach (var property in properties)
{
if(!ignoreProperties.Contains(property.Name))
{
if (unsetProperties.Contains(property.Name))
{
var defaultValue = property.PropertyType.IsValueType ? Activator.CreateInstance(property.PropertyType) : null;
Assert.AreEqual(defaultValue, property.GetValue(obj));
}
else if (IsNumeric(property.PropertyType))
{
Assert.AreEqual(id, property.GetValue(obj));
}
else if (property.PropertyType == typeof(string))
{
Assert.AreEqual(property.Name + id, property.GetValue(obj));
}
else if (property.PropertyType == typeof(bool))
{
Assert.AreEqual(true, property.GetValue(obj));
}
}
}
}
用于測試字段的類型是否為數字：
private static bool IsNumeric(Type type)
{
var NumericTypes = new HashSet<Type>
{
typeof(int), typeof(double), typeof(decimal),
typeof(long), typeof(short), typeof(sbyte),
typeof(byte), typeof(ulong), typeof(ushort),
typeof(uint), typeof(float)
};
return NumericTypes.Contains(Nullable.GetUnderlyingType(type) ?? type);
}
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