iOSのユニットテスト(LogicTests)で和暦設定時のテストを行う ref: http://qiita.com/roothybrid7/items/7185073390e308d5862b

file2.txt

#import "XXXTestCase.h"

#import <OCMock.h>

@interface XXXDateConvertTests : XXXTestCase

@property (nonatomic) NSString *dateString;

@end

@implementation XXXDateConvertTests

- (void)setUp
{
    [super setUp];
    self.dateString = @"20140408";
}

- (void)tearDown
{
    // Put teardown code here. This method is called after the invocation of each test method in the class.
    [super tearDown];
}

// MARK: 日付変換処理だけ抜き出した
- (NSString *)postedAtWithDateFormatter:(NSDateFormatter *)dateFormatter
{
    NSInteger year = [self.dateString substringWithRange:NSMakeRange(0, 4)].integerValue;
    NSInteger month = [self.dateString substringWithRange:NSMakeRange(4, 2)].integerValue;

    [dateFormatter setDateFormat:@"yyyy-MM-dd"];

    // MARK: 和暦設定の場合、年を正常にパースできないのでカレンダーをグレゴリオ暦に変更
//    dateFormatter.calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];

    NSDate *date = [dateFormatter dateFromString:[NSString stringWithFormat:@"%i-%i-1", year, month]];

    [dateFormatter setLocale:[[NSLocale alloc]initWithLocaleIdentifier:@"en_US"]];
    [dateFormatter setDateFormat:@"MMMM, yyyy"];

    return [dateFormatter stringFromDate:date];
}

- (void)testPostedAt
{
    STAssertFalse([[[NSCalendar currentCalendar] calendarIdentifier] isEqualToString:NSJapaneseCalendar], @"");

    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    NSString *resultString = [self postedAtWithDateFormatter:[[NSDateFormatter alloc] init]];

    STAssertEqualObjects(resultString, @"April, 2014", @"");

    [self createJPLocaleWithJapaneseCalendarMock];  // 和暦設定に変更

    NSLog(@"%@", dateFormatter.locale.localeIdentifier);

    dateFormatter = [[NSDateFormatter alloc] init];
    resultString = [self postedAtWithDateFormatter:dateFormatter];
    STAssertFalse([resultString isEqualToString:@"April, 2014"], @"");  // April, 4002になってしまう
}

@end

XXXTestCase.h

#import <SenTestingKit/SenTestingKit.h>

#import <OCMock/OCMock.h>

@interface XXXTestCase : SenTestCase

#pragma mark - NSLocale(ja_JP@calendar=japanese)

/*!
    @method createJPLocaleWithJapaneseCalendarMock
    @abstract iPhoneのカレンダー設定を和暦に書き換えたMockを作成
    @discussion
        iPhoneの[設定]-[一般]-[言語環境]-[カレンダー] = 和暦
 */
- (id)createJPLocaleWithJapaneseCalendarMock;

@end

XXXTestCase.m

@interface XXXTestCase ()

@property (nonatomic) NSMutableArray *mocksToVerify;

@end

@implementation XXXTestCase

- (void)tearDown
{
    for (id mock in self.mocksToVerify) {
        [mock verify];
    }
    self.mocksToVerify = nil;

    // [...]

    [[NSUserDefaults standardUserDefaults] removePersistentDomainForName:XXXTestDomainName];

    [super tearDown];
}

#pragma mark - NSLocale(ja_JP@calendar=japanese)

- (id)createJPLocaleWithJapaneseCalendarMock
{
    NSLocale *locale = [NSLocale localeWithLocaleIdentifier:[NSString stringWithFormat:@"ja_JP@calendar=%@",
                                                             NSJapaneseCalendar]];
    id localeMock = [self autoVerifiedMockForClass:[NSLocale class]];
    [[[[localeMock stub] classMethod] andReturn:locale] systemLocale];
    [[[[localeMock stub] classMethod] andReturn:locale] currentLocale];
    [[[[localeMock stub] classMethod] andReturn:locale] autoupdatingCurrentLocale];

    return localeMock;
}

#pragma mark - Setup and verify mock: http://www.objc.io/issue-1/testing-view-controllers.html

- (void)verifyDuringTearDown:(id)mock
{
    if (!self.mocksToVerify) {
        self.mocksToVerify = @[].mutableCopy;
    }
    [self.mocksToVerify addObject:mock];
}

- (id)autoVerifiedMockForClass:(Class)aClass
{
    id mock = [OCMockObject mockForClass:aClass];
    [self verifyDuringTearDown:mock];
    return mock;
}

- (id)autoVerifiedPartialMockForObject:(id)object
{
    id mock = [OCMockObject partialMockForObject:object];
    [self verifyDuringTearDown:mock];
    return mock;
}

- (id)autoVerifiedNickMockForClass:(Class)aClass
{
    id mock = [OCMockObject niceMockForClass:aClass];
    [self verifyDuringTearDown:mock];
    return mock;
}

@end