Make persistent cache initializer non-failable

Author: aodhol

Sources/SPTPersistentCache.m

@@ -98,9 +98,7 @@ - (instancetype)initWithOptions:(SPTPersistentCacheOptions *)options
                                                                                 queue:_workQueue];
 
 
-        if (![_dataCacheFileManager createCacheDirectory]) {
-            return nil;
-        }
+        [_dataCacheFileManager createCacheDirectory];
     }
     return self;
 }

Tests/SPTPersistentCacheTests.m

@@ -1258,22 +1258,17 @@ - (void)testSerialStoreWithLockDoesntIncrementRefCount
     XCTAssertEqual(header.refCount, 0u, @"refCount must match");
 }
 
-- (void)testInitNilWhenCannotCreateCacheDirectory
+- (void)testInitSucceedsWhenCannotCreateCacheDirectory
 {
     SPTPersistentCacheOptions *options = [SPTPersistentCacheOptions new];
     options.cachePath = [NSTemporaryDirectory() stringByAppendingPathComponent:@"/com.spotify.temppersistent.image.cache"];
     options.cacheIdentifier = @"test";
 
-    Method originalMethod = class_getClassMethod(NSFileManager.class, @selector(defaultManager));
-    IMP originalMethodImplementation = method_getImplementation(originalMethod);
-    IMP fakeMethodImplementation = imp_implementationWithBlock(^ {
-        return nil;
-    });
-    method_setImplementation(originalMethod, fakeMethodImplementation);
+    [[NSFileManager defaultManager] createFileAtPath:options.cachePath contents:nil attributes:nil];
     SPTPersistentCache *cache = [[SPTPersistentCache alloc] initWithOptions:options];
-    method_setImplementation(originalMethod, originalMethodImplementation);
+    [[NSFileManager defaultManager] removeItemAtPath:options.cachePath error:nil];
 
-    XCTAssertNil(cache, @"The cache should be nil if it could not create the directory");
+    XCTAssertNotNil(cache, @"The cache should initialise even if it could not create the directory");
 }
 
 - (void)testFailToLoadDataWhenCallbackAbsent