Fix the unused code warning on test cases

Tests/Tests/SDImageCoderTests.m

@@ -189,8 +189,6 @@
 
 - (void)test16ThatImageIOAnimatedCoderAbstractClass {
     SDImageIOAnimatedCoder *coder = [[SDImageIOAnimatedCoder alloc] init];
-    NSString * testImagePath = [[NSBundle bundleForClass:[self class]] pathForResource:@"TestImage" ofType:@"png"];
-    NSData *testImageData = [NSData dataWithContentsOfFile:testImagePath];
     @try {
         [coder canEncodeToFormat:SDImageFormatPNG];
         XCTFail("Should throw exception");