Simple XCTest base class to handle filesystem based tests

SampleTest.m

//
//  SampleTest.m
//

#import "TestBase.h"

@interface DiscoveryTests : TestBase

@end

@implementation DiscoveryTests {
    
    NSURL *_library;
}

-(BOOL)requireFilesystem {
    
    // Enable filesystem support. If enabled, a new temporary directory is
    // created prior and deleted after each individual test.
    return YES;
}

-(void)setUp {
    
    // This one is important! Call before your setup code.
    [super setUp];
    
    // Now, setup a filesystem structure for the tests...
    
    // Create some directories...
    _library = [self createDirectory:@"JDocLibrary"];
    NSURL *awmDocuments = [self createDirectory:@"AWM" insideDirectory:_library];
    NSURL *companyDocuments = [self createDirectory:@"Company" insideDirectory:_library];
    NSURL *flightDocuments = [self createDirectory:@"Flight" insideDirectory:_library];
    NSURL *operatorDocuments = [self createDirectory:@"Operator" insideDirectory:_library];

    // Copy some test resources...
    [self copyResource:@"eawm_general" toDirectory:awmDocuments];
    [self copyResource:@"jep-afom" toDirectory:operatorDocuments];
    
    // Create temporary files...
    [self createFile:@"test.txt" withContent:nil insideDirectory:companyDocuments];
}

- (void)test {
    
    // Test code
}

@end

TestBase.h

//
//  TestBase.h
//

#import <XCTest/XCTest.h>

@interface TestBase : XCTestCase

@property NSURL *testLocation;

-(BOOL)requireFilesystem;
-(NSURL *)copyResource:(NSString *)resourceName;
-(NSURL *)copyResource:(NSString *)resourceName toDirectory:(NSURL *)directory;
-(NSURL *)createFile:(NSString *)name withContent:(NSData *)content;
-(NSURL *)createFile:(NSString *)name withContent:(NSData *)content insideDirectory:(NSURL *)directory;
-(NSURL *)createDirectory:(NSString *)name;
-(NSURL *)createDirectory:(NSString *)name insideDirectory:(NSURL *)directory;

@end

TestBase.m

//
//  TestBase.m
//

#import "TestBase.h"

@interface TestBase()

-(NSURL *)getResources;

@end

@implementation TestBase

-(BOOL)requireFilesystem {
    
    return NO;
}

-(NSURL *)copyResource:(NSString *)resourceName {
    
    return [self copyResource:resourceName toDirectory:self.testLocation];
}

-(NSURL *)copyResource:(NSString *)resourceName toDirectory:(NSURL *)directory {
    
    NSError *error;
    NSURL *source = [[self getResources] URLByAppendingPathComponent:resourceName];
    NSURL *target = [directory URLByAppendingPathComponent:resourceName];
    
    if (![[NSFileManager defaultManager] copyItemAtURL:source
                                                 toURL:target
                                                 error:&error]) {
        NSLog(@"Error copying test resource: %@", error.localizedDescription);
        return nil;
    }
    
    return target;
}

-(NSURL *)createFile:(NSString *)name withContent:(NSData *)content {
    
    return [self createFile:name withContent:content insideDirectory:self.testLocation];
}

-(NSURL *)createFile:(NSString *)name withContent:(NSData *)content insideDirectory:(NSURL *)directory {
    
    NSURL *file = [directory URLByAppendingPathComponent:name];
    
    if (![[NSFileManager defaultManager] createFileAtPath:file.path contents:content attributes:nil]) {
        NSLog(@"Error creating file: %@", name);
        return nil;
    }
    
    return file;
}

-(NSURL *)createDirectory:(NSString *)name {
    
    return [self createDirectory:name insideDirectory:self.testLocation];
}

-(NSURL *)createDirectory:(NSString *)name insideDirectory:(NSURL *)directory {
    
    NSError *error;
    NSURL *dir = [directory URLByAppendingPathComponent:name];
    
    if (![[NSFileManager defaultManager] createDirectoryAtURL:dir withIntermediateDirectories:YES attributes:nil error:&error]) {
        NSLog(@"Error creating test directory: %@", error.localizedDescription);
        return nil;
    }
    
    return dir;
}

-(void)setUp {
    
    [super setUp];
    
    // Abort tests immediately when an assertion fails
    self.continueAfterFailure = NO;
    
    if ([self requireFilesystem]) {
        
        NSError *error;
        NSURL *location = [[NSURL fileURLWithPath:NSTemporaryDirectory()] URLByAppendingPathComponent:[[NSProcessInfo processInfo] globallyUniqueString]];
        
        if ([[NSFileManager defaultManager] createDirectoryAtURL:location withIntermediateDirectories:YES attributes:nil error:&error]) {
            self.testLocation = location;
        }
        else {
            NSLog(@"Error creating test directory: %@", error.localizedDescription);
        }
    }
    else {
        _testLocation = nil;
    }
}

-(void)tearDown {
    
    if ([self requireFilesystem]) {
        NSFileManager *fileManager = [NSFileManager defaultManager];
        if ([fileManager fileExistsAtPath:self.testLocation.path]) {
            [fileManager removeItemAtPath:self.testLocation.path error:nil];
        }
    }
    
    [super tearDown];
}

-(NSURL *)getResources {
    
    // Path to test resources
    return [[NSBundle bundleForClass:self.class] URLForResource:@"Resources"
                                                  withExtension:nil];
}

@end