Is there any way to emulate user's input in XCTest function? - objective-c

Question

I have method which expects user's input
#implementation TeamFormation
- (void)run {
NSFileHandle *kbd = [NSFileHandle fileHandleWithStandardInput];
NSData *inputData = [kbd availableData];
NSString *option = [[[NSString alloc] initWithData:inputData
encoding:NSUTF8StringEncoding] substringToIndex:1];
NSLog(#"%#",option);
}
#end
Then I would like to cover this method by a test case
#interface TeamFormationTests : XCTestCase
#end
#implementation TeamFormationTests
- (void)testTeamFormation {
TeamFormation *teamFormation = [TeamFormation new];
[teamFormation run];
// emulate user's input here
}
#end
So, how to emulate user's input in test case function?

Answer 1

You have many options how to achieve this. Two obvious below.
Change run to accept an argument
- (void)run to - (void)runWithFileHandle:(NSFileHandle *)handle
your app code can pass stdin filehandle
your test code can pass handle to a file with desired input
Mock it with protocol
Create DataProvider protocol:
#protocol DataProvider
#property(readonly, copy) NSData *availableData;
#end
Make NSFileHandle to conform to this protocol:
#interface NSFileHandle (AvailableDataProvider) <DataProvider>
#end
Store an object implementing this protocol on TeamFormation:
#interface TeamFormation : NSObject
#property (nonatomic, nonnull, strong) id<DataProvider> dataProvider;
- (NSString *)run;
#end
By default, use stdin file handle:
#implementation TeamFormation
- (instancetype)init {
if ((self = [super init]) == nil) {
return nil;
}
_dataProvider = [NSFileHandle fileHandleWithStandardInput];
return self;
}
- (NSString *)run {
NSData *inputData = [self.dataProvider availableData];
return [[[NSString alloc] initWithData:inputData encoding:NSUTF8StringEncoding] substringToIndex:1];
}
#end
Create TestDataProvider in your test:
#interface TestDataProvider: NSObject<DataProvider>
#property (nonatomic, strong, nonnull) NSData *dataToProvide;
#end
#implementation TestDataProvider
- (instancetype)init {
if ((self = [super init]) == nil) {
return nil;
}
_dataToProvide = [NSData new];
return self;
}
- (NSData *)availableData {
return _dataToProvide;
}
#end
And use it in TestFormationTests:
#implementation TeamFormationTests
- (void)testFormationRun {
TestDataProvider *dataProvider = [TestDataProvider new];
TeamFormation *formation = [TeamFormation new];
formation.dataProvider = dataProvider;
XCTAssertThrows([formation run]);
dataProvider.dataToProvide = [#"foo" dataUsingEncoding:NSUTF8StringEncoding];
XCTAssertEqualObjects([formation run], #"f");
dataProvider.dataToProvide = [#"bar" dataUsingEncoding:NSUTF8StringEncoding];
XCTAssertEqualObjects([formation run], #"b");
}
#end