FBSnapshotTestCase/FBSnapshotTestCase.h

/*
 *  Copyright (c) 2015, Facebook, Inc.
 *  All rights reserved.
 *
 *  This source code is licensed under the BSD-style license found in the
 *  LICENSE file in the root directory of this source tree. An additional grant
 *  of patent rights can be found in the PATENTS file in the same directory.
 *
 */

#import <FBSnapshotTestCase/FBSnapshotTestCasePlatform.h>

#import <QuartzCore/QuartzCore.h>

#import <UIKit/UIKit.h>

#import <XCTest/XCTest.h>

/*
 There are three ways of setting reference image directories.

 1. Set the preprocessor macro FB_REFERENCE_IMAGE_DIR to a double quoted
    c-string with the path.
 2. Set an environment variable named FB_REFERENCE_IMAGE_DIR with the path. This
    takes precedence over the preprocessor macro to allow for run-time override.
 3. Keep everything unset, which will cause the reference images to be looked up
    inside the bundle holding the current test, in the
    Resources/ReferenceImages_* directories.
 */
#ifndef FB_REFERENCE_IMAGE_DIR
#define FB_REFERENCE_IMAGE_DIR ""
#endif

/**
 Similar to our much-loved XCTAssert() macros. Use this to perform your test. No need to write an explanation, though.
 @param view The view to snapshot
 @param identifier An optional identifier, used if there are multiple snapshot tests in a given -test method.
 @param suffixes An NSOrderedSet of strings for the different suffixes
 @param tolerance The percentage of pixels that can differ and still count as an 'identical' view
 */
#define FBSnapshotVerifyViewWithOptions(view__, identifier__, suffixes__, tolerance__) \
  FBSnapshotVerifyViewOrLayerWithOptions(View, view__, identifier__, suffixes__, tolerance__)

#define FBSnapshotVerifyView(view__, identifier__) \
  FBSnapshotVerifyViewWithOptions(view__, identifier__, FBSnapshotTestCaseDefaultSuffixes(), 0)


/**
 Similar to our much-loved XCTAssert() macros. Use this to perform your test. No need to write an explanation, though.
 @param layer The layer to snapshot
 @param identifier An optional identifier, used is there are multiple snapshot tests in a given -test method.
 @param suffixes An NSOrderedSet of strings for the different suffixes
 @param tolerance The percentage of pixels that can differ and still count as an 'identical' layer
 */
#define FBSnapshotVerifyLayerWithOptions(layer__, identifier__, suffixes__, tolerance__) \
  FBSnapshotVerifyViewOrLayerWithOptions(Layer, layer__, identifier__, suffixes__, tolerance__)

#define FBSnapshotVerifyLayer(layer__, identifier__) \
  FBSnapshotVerifyLayerWithOptions(layer__, identifier__, FBSnapshotTestCaseDefaultSuffixes(), 0)


#define FBSnapshotVerifyViewOrLayerWithOptions(what__, viewOrLayer__, identifier__, suffixes__, tolerance__) \
{ \
  NSString *referenceImageDirectory = [self getReferenceImageDirectoryWithDefault:(@ FB_REFERENCE_IMAGE_DIR)]; \
  XCTAssertNotNil(referenceImageDirectory, @"Missing value for referenceImagesDirectory - Set FB_REFERENCE_IMAGE_DIR as Environment variable in your scheme.");\
  XCTAssertTrue((suffixes__.count > 0), @"Suffixes set cannot be empty %@", suffixes__); \
  \
  BOOL testSuccess__ = NO; \
  NSError *error__ = nil; \
  NSMutableArray *errors__ = [NSMutableArray array]; \
  \
  if (self.recordMode) { \
    \
    NSString *referenceImagesDirectory__ = [NSString stringWithFormat:@"%@%@", referenceImageDirectory, suffixes__.firstObject]; \
    BOOL referenceImageSaved__ = [self compareSnapshotOf ## what__ :(viewOrLayer__) referenceImagesDirectory:referenceImagesDirectory__ identifier:(identifier__) tolerance:(tolerance__) error:&error__]; \
    if (!referenceImageSaved__) { \
      [errors__ addObject:error__]; \
    } \
  } else { \
    \
    for (NSString *suffix__ in suffixes__) { \
      NSString *referenceImagesDirectory__ = [NSString stringWithFormat:@"%@%@", referenceImageDirectory, suffix__]; \
      BOOL referenceImageAvailable = [self referenceImageRecordedInDirectory:referenceImagesDirectory__ identifier:(identifier__) error:&error__]; \
      \
      if (referenceImageAvailable) { \
        BOOL comparisonSuccess__ = [self compareSnapshotOf ## what__ :(viewOrLayer__) referenceImagesDirectory:referenceImagesDirectory__ identifier:(identifier__) tolerance:(tolerance__) error:&error__]; \
        [errors__ removeAllObjects]; \
        if (comparisonSuccess__) { \
          testSuccess__ = YES; \
          break; \
        } else { \
          [errors__ addObject:error__]; \
        } \
      } else { \
        [errors__ addObject:error__]; \
      } \
    } \
  } \
  XCTAssertTrue(testSuccess__, @"Snapshot comparison failed: %@", errors__.firstObject); \
  XCTAssertFalse(self.recordMode, @"Test ran in record mode. Reference image is now saved. Disable record mode to perform an actual snapshot comparison!"); \
}


/**
 The base class of view snapshotting tests. If you have small UI component, it's often easier to configure it in a test
 and compare an image of the view to a reference image that write lots of complex layout-code tests.
 
 In order to flip the tests in your subclass to record the reference images set @c recordMode to @c YES.
 
 @attention When recording, the reference image directory should be explicitly
            set, otherwise the images may be written to somewhere inside the
            simulator directory.

 For example:
 @code
 - (void)setUp
 {
    [super setUp];
    self.recordMode = YES;
 }
 @endcode
 */
@interface FBSnapshotTestCase : XCTestCase

/**
 When YES, the test macros will save reference images, rather than performing an actual test.
 */
@property (readwrite, nonatomic, assign) BOOL recordMode;

/**
 When @c YES appends the name of the device model and OS to the snapshot file name.
 The default value is @c NO.
 */
@property (readwrite, nonatomic, assign, getter=isDeviceAgnostic) BOOL deviceAgnostic;

/**
 When YES, renders a snapshot of the complete view hierarchy as visible onscreen.
 There are several things that do not work if renderInContext: is used.
 - UIVisualEffect #70
 - UIAppearance #91
 - Size Classes #92
 
 @attention If the view does't belong to a UIWindow, it will create one and add the view as a subview.
 */
@property (readwrite, nonatomic, assign) BOOL usesDrawViewHierarchyInRect;

- (void)setUp NS_REQUIRES_SUPER;
- (void)tearDown NS_REQUIRES_SUPER;

/**
 Performs the comparison or records a snapshot of the layer if recordMode is YES.
 @param layer The Layer to snapshot
 @param referenceImagesDirectory The directory in which reference images are stored.
 @param identifier An optional identifier, used if there are multiple snapshot tests in a given -test method.
 @param tolerance The percentage difference to still count as identical - 0 mean pixel perfect, 1 means I don't care
 @param errorPtr An error to log in an XCTAssert() macro if the method fails (missing reference image, images differ, etc).
 @returns YES if the comparison (or saving of the reference image) succeeded.
 */
- (BOOL)compareSnapshotOfLayer:(CALayer *)layer
      referenceImagesDirectory:(NSString *)referenceImagesDirectory
                    identifier:(NSString *)identifier
                     tolerance:(CGFloat)tolerance
                         error:(NSError **)errorPtr;

/**
 Performs the comparison or records a snapshot of the view if recordMode is YES.
 @param view The view to snapshot
 @param referenceImagesDirectory The directory in which reference images are stored.
 @param identifier An optional identifier, used if there are multiple snapshot tests in a given -test method.
 @param tolerance The percentage difference to still count as identical - 0 mean pixel perfect, 1 means I don't care
 @param errorPtr An error to log in an XCTAssert() macro if the method fails (missing reference image, images differ, etc).
 @returns YES if the comparison (or saving of the reference image) succeeded.
 */
- (BOOL)compareSnapshotOfView:(UIView *)view
     referenceImagesDirectory:(NSString *)referenceImagesDirectory
                   identifier:(NSString *)identifier
                    tolerance:(CGFloat)tolerance
                        error:(NSError **)errorPtr;

/**
 Checks if reference image with identifier based name exists in the reference images directory.
 @param referenceImagesDirectory The directory in which reference images are stored.
 @param identifier An optional identifier, used if there are multiple snapshot tests in a given -test method.
 @param errorPtr An error to log in an XCTAssert() macro if the method fails (missing reference image, images differ, etc).
 @returns YES if reference image exists.
 */
- (BOOL)referenceImageRecordedInDirectory:(NSString *)referenceImagesDirectory
                               identifier:(NSString *)identifier
                                    error:(NSError **)errorPtr;

/**
 Returns the reference image directory.

 Helper function used to implement the assert macros.

 @param dir directory to use if environment variable not specified. Ignored if null or empty.
 */
- (NSString *)getReferenceImageDirectoryWithDefault:(NSString *)dir;

@end