如何测试实现 NSCoding 的简单数据对象 class？

Question

我有一个小数据对象需要序列化和反序列化。假设它被称为 WeatherDetails，它看起来像这样：

WeatherDetails.h

@interface WeatherDetails : NSObject <NSCoding>
{
@private

@protected
}

#pragma mark - Properties

@property (nonatomic, copy) NSString *weatherCode;
@property (nonatomic, copy) NSString *weatherDescription;

@end

WeatherDetails.m

#import "WeatherDetails.h"

@implementation WeatherDetails

NSString *const WEATHER_DETAILS_WEATHER_CODE_KEY = @"s";
NSString *const WEATHER_DETAILS_WEATHER_DESCRIPTION_KEY = @"sT";

#pragma mark - Initialization, NSCoding and Dealloc

- (instancetype)initWithCoder:(NSCoder *)aDecoder
{
    self = [super init];

    _weatherCode = [aDecoder decodeObjectForKey:@"weatherCode"];
    _weatherDescription = [aDecoder decodeObjectForKey:@"weatherDescription"];

    return self;
}

- (void)encodeWithCoder:(NSCoder *)aCoder
{
    [aCoder encodeObject:_weatherCode forKey:@"weatherCode"];
    [aCoder encodeObject:_weatherDescription forKey:@"weatherDescription"];
}

目前我的测试是这样的；

#import <XCTest/XCTest.h>
#import <OCMock/OCMock.h>
#import "WeatherDetails.h"
@interface WeatherDetailsTests : XCTestCase

@end

@implementation WeatherDetailsTests

- (void)testThatWeatherCodeIsEncoded
{
    WeatherDetails *details = [[WeatherDetails alloc] init];
    [details setWeatherCode:@"A"];

    NSData *archive = [NSKeyedArchiver archivedDataWithRootObject:details];

    WeatherDetails *unarchive = [NSKeyedUnarchiver unarchiveObjectWithData:archive];

    XCTAssertEqualObjects(@"A", [unarchive weatherCode]);
}

- (void)testThatWeatherDescriptionIsEncoded
{
    WeatherDetails *details = [[WeatherDetails alloc] init];
    [details setWeatherDescription:@"A"];

    NSData *archive = [NSKeyedArchiver archivedDataWithRootObject:details];

    WeatherDetails *unarchive = [NSKeyedUnarchiver unarchiveObjectWithData:archive];

    XCTAssertEqualObjects(@"A", [unarchive weatherDescription]);
}

我有一种直觉，这种测试所有属性是否正确编码的方法并不是真正的最佳方法，因为存在重复，但我真的想不出更好的方法。有没有人对我有改进的建议？

Answer 1

您真正要测试的是对象在归档前后是否相同。

在您的 WeatherDetails 中实施一个方法来比较对象（或覆盖 isEqual:）。

- (BOOL)isEqualToWeatherDetails:(WeatherDetails *)details
{
    if (![details isKindOfClass:[WeatherDetails class]]) return NO;
    return [self.weatherCode == details.weatherCode && self.weatherDescription isEqualToString:details.weatherDescription];
}

然后您可以一次进行所有相等比较：

- (void)testNSCoder
{
    WeatherDetails *details = [[WeatherDetails alloc] init];
    [details setWeatherCode:@"A"];
    details.weatherDescription = @"Cloudy";

    NSData *archive = [NSKeyedArchiver archivedDataWithRootObject:details];

    WeatherDetails *unarchive = [NSKeyedUnarchiver unarchiveObjectWithData:archive];

    XCTAssertTrue([details isEqualToWeatherDetails:unarchive]);
}

如果你覆盖 isEqual: 那么你可以比较这样做：

XCTAssertEqualObjects(details, unarchive);

Apple 倾向于添加额外的方法（isEqualToArray:、isEqualToDictionary:）。 isEqual: 被 NSSet 和 NSDictionary 等集合使用

Answer 2

最后我通过应用 custom assertion;

改进了它

When To Use It

We should consider creating a Custom Assertion whenever any of the following are true:

We find ourselves writing (or cloning) the same assertion logic in test after test

We find ourselves writing Conditional Test Logic in the result verification part of our tests. That is, our calls to Assertion Methods are embedded in if statements or loops.

The result verification parts of our tests are suffering from Obscure Test because we are using procedural rather than declarative result verification in the tests.

We find ourselves doing Frequent Debugging whenever assertions fail because they do not provide enough information.

自定义断言当前如下所示：

/*!
 * @define XCTAssertEqualSerialized(value, object, selector)
 * Serializes (\a object), then desirializes it and compares result's property (\a propertyName) to (\a value) with XCTAssertEqualObjects
 * @param value Value to compare.
 * @param object Object to serialize.
 * @param selector Objects property to compare.
 */

#define XCTAssertEqualSerialized(value, object, selector) \
({ \
NSData *archived = [NSKeyedArchiver archivedDataWithRootObject:object]; \
NSObject *unarchived = [NSKeyedUnarchiver unarchiveObjectWithData:archived]; \
XCTAssertEqualObjects(value, [unarchived valueForKeyPath:NSStringFromSelector(selector)]); \
})

/*!
 * @define XCTAssertNotNilSerialized(object, selector)
 * Serializes (\a object), then desirializes it and checks result's property (\a propertyName) is not nil with XCTAssertNotNil
 * @param object Object to serialize.
 * @param selector Objects property to compare.
 */

#define XCTAssertNotNilSerialized(object, selector) \
({ \
NSData *archived = [NSKeyedArchiver archivedDataWithRootObject:object]; \
NSObject *unarchived = [NSKeyedUnarchiver unarchiveObjectWithData:archived]; \
XCTAssertNotNil([unarchived valueForKeyPath:NSStringFromSelector(selector)]); \
})

这导致测试看起来像这样：

- (void)testThatWeatherCodeIsEncoded
{
    WeatherDetails *details = [[WeatherDetails alloc] init];
    [details setWeatherCode:@"A"];

    XCTAssertEqualSerialized(@"A", details, @selector(weatherCode));
}

- (void)testThatWeatherDescriptionIsEncoded
{
    WeatherDetails *details = [[WeatherDetails alloc] init];
    [details setWeatherDescription:@"A"];

    XCTAssertEqualSerialized(@"A", details, @selector(weatherDescription));
}

如何测试实现 NSCoding 的简单数据对象 class？

How to test a simple data object class which implements NSCoding?

unit-testing

ios

xctest