Refactored the `SDWebImageDecoderTests` a bit. Per DRY, created `verifyCoder:wit…

…hLocalImageURL:isAnimatedImage:` method that will take a imageURL and a coder and will check decoding and encoding back and forth, sizes and so. Reusing this method for the static WebP image, for the animated WebP image and for the GIF.

@@ -47,7 +47,7 @@ NSString *kImageTestKey = @"TestImageKey.jpg";
         [self.sharedImageCache diskImageExistsWithKey:kImageTestKey completion:^(BOOL isInCache) {
             if (!isInCache) {
                 [self.sharedImageCache calculateSizeWithCompletionBlock:^(NSUInteger fileCount, NSUInteger totalSize) {
-                    expect(fileCount).to.beLessThan(100);
+                    expect(fileCount).to.equal(0);
                     [expectation fulfill];
                 }];
             } else {

@@ -12,6 +12,7 @@
 #import <SDWebImage/SDWebImageWebPCoder.h>
 #import <SDWebImage/UIImage+ForceDecode.h>
 #import <SDWebImage/SDWebImageGIFCoder.h>
+#import <SDWebImage/NSData+ImageContentType.h>
 
 @interface SDWebImageDecoderTests : SDTestCase
 
@@ -97,65 +98,63 @@
 
 - (void)test09ThatStaticWebPCoderWorks {
     NSURL *staticWebPURL = [[NSBundle bundleForClass:[self class]] URLForResource:@"TestImageStatic" withExtension:@"webp"];
-    NSData *staticWebPData = [NSData dataWithContentsOfURL:staticWebPURL];
-    expect([[SDWebImageWebPCoder sharedCoder] canDecodeFromData:staticWebPData]).to.beTruthy();
-    expect([[SDWebImageImageIOCoder sharedCoder] canDecodeFromData:staticWebPData]).to.beFalsy();
-    UIImage *staticWebPImage = [[SDWebImageWebPCoder sharedCoder] decodedImageWithData:staticWebPData];
-    expect(staticWebPImage).toNot.beNil();
-    
-    expect([[SDWebImageWebPCoder sharedCoder] canEncodeToFormat:SDImageFormatWebP]).to.beTruthy();
-    expect([[SDWebImageImageIOCoder sharedCoder] canEncodeToFormat:SDImageFormatWebP]).to.beFalsy();
-    NSData *outputData = [[SDWebImageWebPCoder sharedCoder] encodedDataWithImage:staticWebPImage format:SDImageFormatWebP];
-    expect(outputData).toNot.beNil();
+    [self verifyCoder:[SDWebImageWebPCoder sharedCoder]
+    withLocalImageURL:staticWebPURL
+      isAnimatedImage:NO];
 }
 
 - (void)test10ThatAnimatedWebPCoderWorks {
     NSURL *animatedWebPURL = [[NSBundle bundleForClass:[self class]] URLForResource:@"TestImageAnimated" withExtension:@"webp"];
-    NSData *animatedWebPData = [NSData dataWithContentsOfURL:animatedWebPURL];
-    expect([[SDWebImageWebPCoder sharedCoder] canDecodeFromData:animatedWebPData]).to.beTruthy();
-    UIImage *animatedWebPImage = [[SDWebImageWebPCoder sharedCoder] decodedImageWithData:animatedWebPData];
-    expect(animatedWebPImage).toNot.beNil();
-    expect(animatedWebPImage.images.count).to.beGreaterThan(0);
-    CGSize imageSize = animatedWebPImage.size;
-    CGFloat imageScale = animatedWebPImage.scale;
-    [animatedWebPImage.images enumerateObjectsUsingBlock:^(UIImage * _Nonnull image, NSUInteger idx, BOOL * _Nonnull stop) {
-        CGSize size = image.size;
-        CGFloat scale = image.scale;
-        expect(imageSize.width).to.equal(size.width);
-        expect(imageSize.height).to.equal(size.height);
-        expect(imageScale).to.equal(scale);
-    }];
-    
-    expect([[SDWebImageWebPCoder sharedCoder] canEncodeToFormat:SDImageFormatWebP]).to.beTruthy();
-    NSData *outputData = [[SDWebImageWebPCoder sharedCoder] encodedDataWithImage:animatedWebPImage format:SDImageFormatWebP];
-    expect(outputData).toNot.beNil();
+    [self verifyCoder:[SDWebImageWebPCoder sharedCoder]
+    withLocalImageURL:animatedWebPURL
+      isAnimatedImage:YES];
 }
 
 - (void)test20ThatOurGIFCoderWorksNotFLAnimatedImage {
     NSURL *gifURL = [[NSBundle bundleForClass:[self class]] URLForResource:@"TestImage" withExtension:@"gif"];
-    NSData *gifData = [NSData dataWithContentsOfURL:gifURL];
-    expect([[SDWebImageGIFCoder sharedCoder] canDecodeFromData:gifData]).to.beTruthy();
-    // the IOCoder can also decode GIF
-    expect([[SDWebImageImageIOCoder sharedCoder] canDecodeFromData:gifData]).to.beTruthy();
-    UIImage *gifImage = [[SDWebImageGIFCoder sharedCoder] decodedImageWithData:gifData];
-    expect(gifImage).toNot.beNil();
-    expect(gifImage.images.count).to.beGreaterThan(0);
-    CGSize imageSize = gifImage.size;
-    CGFloat imageScale = gifImage.scale;
-    [gifImage.images enumerateObjectsUsingBlock:^(UIImage * _Nonnull image, NSUInteger idx, BOOL * _Nonnull stop) {
-        CGSize size = image.size;
-        CGFloat scale = image.scale;
-        expect(imageSize.width).to.equal(size.width);
-        expect(imageSize.height).to.equal(size.height);
-        expect(imageScale).to.equal(scale);
-    }];
+    [self verifyCoder:[SDWebImageGIFCoder sharedCoder]
+    withLocalImageURL:gifURL
+      isAnimatedImage:YES];
+}
+
+- (void)verifyCoder:(id<SDWebImageCoder>)coder
+  withLocalImageURL:(NSURL *)imageUrl
+    isAnimatedImage:(BOOL)isAnimated {
+    NSData *inputImageData = [NSData dataWithContentsOfURL:imageUrl];
+    expect(inputImageData).toNot.beNil();
+    SDImageFormat inputImageFormat = [NSData sd_imageFormatForImageData:inputImageData];
+    expect(inputImageFormat).toNot.equal(SDImageFormatUndefined);
+    
+    // 1 - check if we can decode - should be true
+    expect([coder canDecodeFromData:inputImageData]).to.beTruthy();
+    
+    // 2 - decode from NSData to UIImage and check it
+    UIImage *inputImage = [coder decodedImageWithData:inputImageData];
+    expect(inputImage).toNot.beNil();
+    
+    if (isAnimated) {
+        // 2a - check images count > 0 (only for animated images)
+        expect(inputImage.images.count).to.beGreaterThan(0);
+        
+        // 2b - check image size and scale for each frameImage (only for animated images)
+        CGSize imageSize = inputImage.size;
+        CGFloat imageScale = inputImage.scale;
+        [inputImage.images enumerateObjectsUsingBlock:^(UIImage * frameImage, NSUInteger idx, BOOL * stop) {
+            expect(imageSize).to.equal(frameImage.size);
+            expect(imageScale).to.equal(frameImage.scale);
+        }];
+    }
     
-    expect([[SDWebImageGIFCoder sharedCoder] decompressedImageWithImage:gifImage data:nil  options:nil]).to.equal(gifImage);
+    // 3 - check if we can encode to the original format
+    expect([coder canEncodeToFormat:inputImageFormat]).to.beTruthy();
     
-    expect([[SDWebImageGIFCoder sharedCoder] canEncodeToFormat:SDImageFormatGIF]).to.beTruthy();
-    expect([[SDWebImageImageIOCoder sharedCoder] canEncodeToFormat:SDImageFormatGIF]).to.beTruthy();
-    NSData *outputData = [[SDWebImageGIFCoder sharedCoder] encodedDataWithImage:gifImage format:SDImageFormatGIF];
-    expect(outputData).toNot.beNil();
+    // 4 - encode from UIImage to NSData using the inputImageFormat and check it
+    NSData *outputImageData = [coder encodedDataWithImage:inputImage format:inputImageFormat];
+    expect(outputImageData).toNot.beNil();
+    UIImage *outputImage = [coder decodedImageWithData:outputImageData];
+    expect(outputImage.size).to.equal(inputImage.size);
+    expect(outputImage.scale).to.equal(inputImage.scale);
+    expect(outputImage.images.count).to.equal(inputImage.images.count);
 }
 
 @end