material-components_material-components-ios/components/Collections/tests/unit/MDCCollectionViewFlowLayoutTests.m

/*
 Copyright 2017-present the Material Components for iOS authors. All Rights Reserved.

 Licensed under the Apache License Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing software
 distributed under the License is distributed on an "AS IS" BASIS
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */

#import <XCTest/XCTest.h>
#import "MaterialCollections.h"

@interface FakeUICollectionViewUpdateItem : UICollectionViewUpdateItem {
  NSIndexPath *_indexPathBeforeUpdate;
  NSIndexPath *_indexPathAfterUpdate;
  UICollectionUpdateAction _updateAction;
}
@end

@implementation FakeUICollectionViewUpdateItem

- (void)setIndexPathBeforeUpdate:(NSIndexPath *)indexPath {
  _indexPathBeforeUpdate = indexPath;
}

- (NSIndexPath *)indexPathBeforeUpdate {
  return _indexPathBeforeUpdate;
}

- (void)setIndexPathAfterUpdate:(NSIndexPath *)indexPath {
  _indexPathAfterUpdate = indexPath;
}

- (NSIndexPath *)indexPathAfterUpdate {
  return _indexPathAfterUpdate;
}

- (void)setUpdateAction:(UICollectionUpdateAction)updateAction {
  _updateAction = updateAction;
}

- (UICollectionUpdateAction)updateAction {
  return _updateAction;
}

@end

@interface MDCCollectionViewFlowLayoutTests : XCTestCase <UICollectionViewDataSource>

@end

@implementation MDCCollectionViewFlowLayoutTests

- (void)testPrepareForCollectionViewUpdatesInsertSection {
  // Given
  MDCCollectionViewFlowLayout *layout = [[MDCCollectionViewFlowLayout alloc] init];

  UICollectionView *collectionView =
      [[UICollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:layout];
  collectionView.dataSource = self;
  NSMutableArray<UICollectionViewUpdateItem *> *updates = [NSMutableArray array];
  FakeUICollectionViewUpdateItem *section1Update = [[FakeUICollectionViewUpdateItem alloc] init];
  [section1Update setIndexPathBeforeUpdate:nil];
  [section1Update setIndexPathAfterUpdate:[NSIndexPath indexPathForItem:NSNotFound inSection:1]];
  section1Update.updateAction = UICollectionUpdateActionInsert;
  [updates addObject:section1Update];

  // When
  [layout prepareForCollectionViewUpdates:[updates copy]];

  // Then
  UICollectionViewLayoutAttributes *section1Attributes = [layout
      initialLayoutAttributesForAppearingItemAtIndexPath:[NSIndexPath indexPathForItem:NSNotFound
                                                                             inSection:1]];
  XCTAssertNotNil(section1Attributes,
                  @"Section 1 has an insert so the attributes should be non-nil.");
  XCTAssertEqual(0, section1Attributes.alpha);
  XCTAssertTrue(CGRectEqualToRect(CGRectZero, section1Attributes.bounds),
                @"The bounds should be the zero rect.\nReceived: %@",
                NSStringFromCGRect(section1Attributes.bounds));
  XCTAssertTrue(
      CGAffineTransformEqualToTransform(CGAffineTransformIdentity, section1Attributes.transform),
      @"The transform should be the transform because the attributes have zero-height "
      @"bounds.\nIdentity: %@\nReceived: %@",
      NSStringFromCGAffineTransform(CGAffineTransformIdentity),
      NSStringFromCGAffineTransform(section1Attributes.transform));

  UICollectionViewLayoutAttributes *section0Attributes = [layout
      initialLayoutAttributesForAppearingItemAtIndexPath:[NSIndexPath indexPathForItem:NSNotFound
                                                                             inSection:0]];
  XCTAssertNil(section0Attributes, @"Section 0 has no inserts so the attributes should be nil.");
  section1Attributes = [layout
      finalLayoutAttributesForDisappearingItemAtIndexPath:[NSIndexPath indexPathForItem:NSNotFound
                                                                              inSection:1]];
  XCTAssertNil(section1Attributes);
  section0Attributes = [layout
      finalLayoutAttributesForDisappearingItemAtIndexPath:[NSIndexPath indexPathForItem:NSNotFound
                                                                              inSection:0]];
  XCTAssertNil(section0Attributes);
}

- (void)testPrepareForCollectionViewUpdatesInsertItem {
  // Given
  MDCCollectionViewFlowLayout *layout = [[MDCCollectionViewFlowLayout alloc] init];

  UICollectionView *collectionView =
      [[UICollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:layout];
  collectionView.dataSource = self;
  NSMutableArray<UICollectionViewUpdateItem *> *updates = [NSMutableArray array];
  FakeUICollectionViewUpdateItem *section0Update = [[FakeUICollectionViewUpdateItem alloc] init];
  [section0Update setIndexPathBeforeUpdate:nil];
  [section0Update setIndexPathAfterUpdate:[NSIndexPath indexPathForItem:0 inSection:0]];
  section0Update.updateAction = UICollectionUpdateActionInsert;
  [updates addObject:section0Update];

  // When
  [layout prepareForCollectionViewUpdates:[updates copy]];

  // Then
  UICollectionViewLayoutAttributes *section1Attributes =
      [layout initialLayoutAttributesForAppearingItemAtIndexPath:[NSIndexPath indexPathForItem:1
                                                                                     inSection:1]];
  XCTAssertNotNil(section1Attributes,
                  @"Section 1 has an insert so the attributes should be non-nil.");
  XCTAssertEqual(1, section1Attributes.alpha);
  XCTAssertTrue(CGRectEqualToRect(CGRectZero, section1Attributes.bounds),
                @"The bounds should be the zero rect.\nReceived: %@",
                NSStringFromCGRect(section1Attributes.bounds));
  XCTAssertTrue(
      CGAffineTransformEqualToTransform(CGAffineTransformIdentity, section1Attributes.transform),
      @"The transform should be the transform because the attributes have zero-height "
      @"bounds.\nIdentity: %@\nReceived: %@",
      NSStringFromCGAffineTransform(CGAffineTransformIdentity),
      NSStringFromCGAffineTransform(section1Attributes.transform));

  UICollectionViewLayoutAttributes *section0Attributes =
      [layout initialLayoutAttributesForAppearingItemAtIndexPath:[NSIndexPath indexPathForItem:0
                                                                                     inSection:0]];
  XCTAssertNotNil(section0Attributes,
                  @"Section 0 has an insert so the attributes should be non-nil.");
  XCTAssertEqual(0, section0Attributes.alpha);
  XCTAssertTrue(CGRectEqualToRect(CGRectZero, section0Attributes.bounds),
                @"The bounds should be the zero rect.\nReceived: %@",
                NSStringFromCGRect(section0Attributes.bounds));
  XCTAssertTrue(
      CGAffineTransformEqualToTransform(CGAffineTransformIdentity, section0Attributes.transform),
      @"The transform should be the transform because the attributes have zero-height "
      @"bounds.\nIdentity: %@\nReceived: %@",
      NSStringFromCGAffineTransform(CGAffineTransformIdentity),
      NSStringFromCGAffineTransform(section0Attributes.transform));

  section1Attributes =
      [layout finalLayoutAttributesForDisappearingItemAtIndexPath:[NSIndexPath indexPathForItem:0
                                                                                      inSection:1]];
  XCTAssertNil(section1Attributes);
  section0Attributes =
      [layout finalLayoutAttributesForDisappearingItemAtIndexPath:[NSIndexPath indexPathForItem:0
                                                                                      inSection:0]];
  XCTAssertNil(section0Attributes);
}

- (void)testPrepareForCollectionViewUpdatesDeleteSection {
  // Given
  MDCCollectionViewFlowLayout *layout = [[MDCCollectionViewFlowLayout alloc] init];
  UICollectionView *collectionView =
      [[UICollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:layout];
  collectionView.dataSource = self;
  NSMutableArray<UICollectionViewUpdateItem *> *updates = [NSMutableArray array];
  FakeUICollectionViewUpdateItem *section1Update = [[FakeUICollectionViewUpdateItem alloc] init];
  [section1Update setIndexPathBeforeUpdate:[NSIndexPath indexPathForItem:NSNotFound inSection:1]];
  [section1Update setIndexPathAfterUpdate:nil];
  section1Update.updateAction = UICollectionUpdateActionDelete;
  [updates addObject:section1Update];

  // When
  [layout prepareForCollectionViewUpdates:[updates copy]];

  // Then
  UICollectionViewLayoutAttributes *section1Attributes = [layout
      initialLayoutAttributesForAppearingItemAtIndexPath:[NSIndexPath indexPathForItem:NSNotFound
                                                                             inSection:1]];
  XCTAssertNil(section1Attributes, @"Section 1 has no inserts so the attributes should be nil.");
  UICollectionViewLayoutAttributes *section0Attributes = [layout
      initialLayoutAttributesForAppearingItemAtIndexPath:[NSIndexPath indexPathForItem:NSNotFound
                                                                             inSection:0]];
  XCTAssertNil(section0Attributes, @"Section 0 has no inserts so the attributes should be nil.");
  section1Attributes = [layout
      finalLayoutAttributesForDisappearingItemAtIndexPath:[NSIndexPath indexPathForItem:NSNotFound
                                                                              inSection:1]];
  XCTAssertNil(section1Attributes);
  section0Attributes = [layout
      finalLayoutAttributesForDisappearingItemAtIndexPath:[NSIndexPath indexPathForItem:NSNotFound
                                                                              inSection:0]];
  XCTAssertNil(section0Attributes);
}

- (void)testPrepareForCollectionViewUpdatesDeleteItem {
  // Given
  MDCCollectionViewFlowLayout *layout = [[MDCCollectionViewFlowLayout alloc] init];
  UICollectionView *collectionView =
      [[UICollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:layout];
  collectionView.dataSource = self;
  NSMutableArray<UICollectionViewUpdateItem *> *updates = [NSMutableArray array];
  FakeUICollectionViewUpdateItem *section1Update = [[FakeUICollectionViewUpdateItem alloc] init];
  [section1Update setIndexPathBeforeUpdate:[NSIndexPath indexPathForItem:1 inSection:1]];
  [section1Update setIndexPathAfterUpdate:nil];
  section1Update.updateAction = UICollectionUpdateActionDelete;
  [updates addObject:section1Update];

  // When
  [layout prepareForCollectionViewUpdates:[updates copy]];

  // Then
  UICollectionViewLayoutAttributes *section1Attributes =
      [layout initialLayoutAttributesForAppearingItemAtIndexPath:[NSIndexPath indexPathForItem:1
                                                                                     inSection:1]];
  XCTAssertNotNil(section1Attributes,
                  @"Section 1 has a delete so the attributes should be non-nil.");
  XCTAssertEqual(1, section1Attributes.alpha);
  XCTAssertTrue(CGRectEqualToRect(CGRectZero, section1Attributes.bounds),
                @"The bounds should be the zero rect.\nReceived: %@",
                NSStringFromCGRect(section1Attributes.bounds));
  XCTAssertTrue(
      CGAffineTransformEqualToTransform(CGAffineTransformIdentity, section1Attributes.transform),
      @"The transform should be the transform because the attributes have zero-height "
      @"bounds.\nIdentity: %@\nReceived: %@",
      NSStringFromCGAffineTransform(CGAffineTransformIdentity),
      NSStringFromCGAffineTransform(section1Attributes.transform));
  UICollectionViewLayoutAttributes *section0Attributes =
      [layout initialLayoutAttributesForAppearingItemAtIndexPath:[NSIndexPath indexPathForItem:1
                                                                                     inSection:0]];
  XCTAssertNotNil(section0Attributes,
                  @"Section 0 has a delete so the attributes should be non-nil.");
  XCTAssertEqual(1, section0Attributes.alpha);
  XCTAssertTrue(CGRectEqualToRect(CGRectZero, section0Attributes.bounds),
                @"The bounds should be the zero rect.\nReceived: %@",
                NSStringFromCGRect(section0Attributes.bounds));
  XCTAssertTrue(
      CGAffineTransformEqualToTransform(CGAffineTransformIdentity, section0Attributes.transform),
      @"The transform should be the transform because the attributes have zero-height "
      @"bounds.\nIdentity: %@\nReceived: %@",
      NSStringFromCGAffineTransform(CGAffineTransformIdentity),
      NSStringFromCGAffineTransform(section0Attributes.transform));
  section1Attributes =
      [layout finalLayoutAttributesForDisappearingItemAtIndexPath:[NSIndexPath indexPathForItem:1
                                                                                      inSection:1]];
  XCTAssertNil(section1Attributes);
  section0Attributes =
      [layout finalLayoutAttributesForDisappearingItemAtIndexPath:[NSIndexPath indexPathForItem:1
                                                                                      inSection:0]];
  XCTAssertNil(section0Attributes);
}

#pragma mark - <UICollectionViewDataSource>

// Never called in these tests
- (UICollectionViewCell *)collectionView:(UICollectionView *)cv
                  cellForItemAtIndexPath:(nonnull NSIndexPath *)indexPath {
  return nil;
}

- (NSInteger)collectionView:(UICollectionView *)collectionView
     numberOfItemsInSection:(NSInteger)section {
  return 2;
}

- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
  return 2;
}

@end