Implement AutoRecord for new snapshots.

Provides an autoRecord parameter. If set, new tests that do not have a reference image will still execute, will return a failure, and will provide a fail image which is a snapshot of the view. This provides the opportunity for the user to review the image and decide whether to set it as a reference image. If recordMode == true, autoRecord is ignored and behavior is as previously.

FBSnapshotTestCase/FBSnapshotTestCase.h

@@ -92,6 +92,12 @@
  */
 @property (readwrite, nonatomic, assign) BOOL recordMode;
 
+/**
+ When YES, a test will run and fail when no reference image exists, without needing to run
+ recordMode first. The fail image is stored and can be reviewed and accepted as a reference.
+ */
+@property (readwrite, nonatomic, assign) BOOL autoRecord;
+
 /**
  When @c YES appends the name of the device model and OS to the snapshot file name.
  The default value is @c NO.

FBSnapshotTestCase/FBSnapshotTestCase.m

@@ -39,6 +39,17 @@ - (void)setRecordMode:(BOOL)recordMode
   _snapshotController.recordMode = recordMode;
 }
 
+- (BOOL)autoRecord
+{
+    return _snapshotController.autoRecord;
+}
+
+- (void)setAutoRecord:(BOOL)autoRecord
+{
+    NSAssert1(_snapshotController, @"%s cannot be called before [super setUp]", __FUNCTION__);
+    _snapshotController.autoRecord = autoRecord;
+}
+
 - (BOOL)isDeviceAgnostic
 {
   return _snapshotController.deviceAgnostic;
@@ -121,12 +132,15 @@ - (NSString *)snapshotVerifyViewOrLayer:(id)viewOrLayer
     }
   }
 
-  if (!testSuccess) {
-    return [NSString stringWithFormat:@"Snapshot comparison failed: %@", errors.firstObject];
-  }
   if (self.recordMode) {
     return @"Test ran in record mode. Reference image is now saved. Disable record mode to perform an actual snapshot comparison!";
   }
+  else if (!testSuccess && !self.autoRecord) {
+    return [NSString stringWithFormat:@"Snapshot comparison failed: %@", errors.firstObject];
+  }
+  else if (!testSuccess && self.autoRecord) {
+    return [NSString stringWithFormat:@"No previous reference image. New image has been stored for approval."];
+  }
 
   return nil;
 }

FBSnapshotTestCase/FBSnapshotTestController.h

@@ -51,6 +51,11 @@ extern NSString *const FBDiffedImageKey;
  */
 @interface FBSnapshotTestController : NSObject
 
+/**
+ Auto record snapshots on first run of new tests.
+ */
+@property (readwrite, nonatomic, assign) BOOL autoRecord;
+
 /**
  Record snapshots.
  */

FBSnapshotTestCase/FBSnapshotTestController.m

@@ -106,7 +106,7 @@ - (UIImage *)referenceImageForSelector:(SEL)selector
   UIImage *image = [UIImage imageWithContentsOfFile:filePath];
   if (nil == image && NULL != errorPtr) {
     BOOL exists = [_fileManager fileExistsAtPath:filePath];
-    if (!exists) {
+    if (!exists && !self.autoRecord) {
       *errorPtr = [NSError errorWithDomain:FBSnapshotTestControllerErrorDomain
                                       code:FBSnapshotTestControllerErrorCodeNeedsRecord
                                   userInfo:@{
@@ -177,7 +177,7 @@ - (BOOL)saveFailedReferenceImage:(UIImage *)referenceImage
     return NO;
   }
 
-  if (![referencePNGData writeToFile:referencePath options:NSDataWritingAtomic error:errorPtr]) {
+  if (!self.autoRecord && ![referencePNGData writeToFile:referencePath options:NSDataWritingAtomic error:errorPtr]) {
     return NO;
   }
 
@@ -196,7 +196,7 @@ - (BOOL)saveFailedReferenceImage:(UIImage *)referenceImage
   UIImage *diffImage = [referenceImage fb_diffWithImage:testImage];
   NSData *diffImageData = UIImagePNGRepresentation(diffImage);
 
-  if (![diffImageData writeToFile:diffPath options:NSDataWritingAtomic error:errorPtr]) {
+  if (!self.autoRecord && ![diffImageData writeToFile:diffPath options:NSDataWritingAtomic error:errorPtr]) {
     return NO;
   }
 
@@ -280,9 +280,16 @@ - (BOOL)_performPixelComparisonWithViewOrLayer:(id)viewOrLayer
                                          error:(NSError **)errorPtr
 {
   UIImage *referenceImage = [self referenceImageForSelector:selector identifier:identifier error:errorPtr];
-  if (nil != referenceImage) {
+  if (nil != referenceImage || self.autoRecord == true) {
     UIImage *snapshot = [self _imageForViewOrLayer:viewOrLayer];
-    BOOL imagesSame = [self compareReferenceImage:referenceImage toImage:snapshot tolerance:tolerance error:errorPtr];
+    BOOL imagesSame;
+
+    if (self.autoRecord) {
+      imagesSame = NO;
+    } else {
+      imagesSame = [self compareReferenceImage:referenceImage toImage:snapshot tolerance:tolerance error:errorPtr];
+    }
+
     if (!imagesSame) {
       NSError *saveError = nil;
       if ([self saveFailedReferenceImage:referenceImage testImage:snapshot selector:selector identifier:identifier error:&saveError] == NO) {

FBSnapshotTestCase/SwiftSupport.swift

@@ -24,13 +24,18 @@
       if let envReferenceImageDirectory = envReferenceImageDirectory {
         for suffix in suffixes {
           let referenceImagesDirectory = "\(envReferenceImageDirectory)\(suffix)"
+          var referenceImageExists = true
           if viewOrLayer.isKind(of: UIView.self) {
             do {
               try compareSnapshot(of: viewOrLayer as! UIView, referenceImagesDirectory: referenceImagesDirectory, identifier: identifier, tolerance: tolerance)
               comparisonSuccess = true
             } catch let error1 as NSError {
-              error = error1
               comparisonSuccess = false
+              if error1.code == 1 {
+                referenceImageExists = false
+              } else {
+                error = error1
+              }
             }
           } else if viewOrLayer.isKind(of: CALayer.self) {
             do {
@@ -39,6 +44,11 @@
             } catch let error1 as NSError {
               error = error1
               comparisonSuccess = false
+              if error1.code == 1 {
+                referenceImageExists = false
+              } else {
+                error = error1
+              }
             }
           } else {
             assertionFailure("Only UIView and CALayer classes can be snapshotted")
@@ -49,7 +59,13 @@
           if comparisonSuccess || recordMode {
             break
           }
+
+          assert(self.autoRecord == false || referenceImageExists, message: "No previous reference image. New image has been stored for approval.", file: file, line: line)
 
+          if self.autoRecord && !referenceImageExists {
+            break
+          }
+
           assert(comparisonSuccess, message: "Snapshot comparison failed: \(String(describing: error))", file: file, line: line)
         }
       } else {
@@ -86,16 +102,24 @@ public extension FBSnapshotTestCase {
             try compareSnapshotOfView(viewOrLayer as! UIView, referenceImagesDirectory: referenceImagesDirectory, identifier: identifier, tolerance: tolerance)
             comparisonSuccess = true
           } catch let error1 as NSError {
-            error = error1
             comparisonSuccess = false
+            if error1.code == 1 {
+              referenceImageExists = false
+            } else {
+              error = error1
+            }
           }
         } else if viewOrLayer.isKindOfClass(CALayer) {
           do {
             try compareSnapshotOfLayer(viewOrLayer as! CALayer, referenceImagesDirectory: referenceImagesDirectory, identifier: identifier, tolerance: tolerance)
             comparisonSuccess = true
           } catch let error1 as NSError {
-            error = error1
             comparisonSuccess = false
+            if error1.code == 1 {
+              referenceImageExists = false
+            } else {
+              error = error1
+            }
           }
         } else {
           assertionFailure("Only UIView and CALayer classes can be snapshotted")
@@ -107,6 +131,12 @@ public extension FBSnapshotTestCase {
           break
         }
 
+        assert(self.autoRecord == false || referenceImageExists, message: "No previous reference image. New image has been stored for approval.", file: file, line: line)
+
+        if self.autoRecord && !referenceImageExists {
+          break
+        }
+
         assert(comparisonSuccess, message: "Snapshot comparison failed: \(error)", file: file, line: line)
       }
     } else {