IGListKit/Tests/IGListViewVisibilityTrackerTests.m

/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

#import <XCTest/XCTest.h>

#import <UIKit/UIKit.h>

#import "IGListViewVisibilityTrackerInternal.h"

@interface IGListViewVisibilityTrackerTests : XCTestCase
@property (nonatomic, strong) UIWindow *window;
@property (nonatomic, strong) UIView *containerView;
@property (nonatomic, strong) UIView *view;
@property (nonatomic, strong) IGListViewVisibilityTracker *tracker;
@end

@implementation IGListViewVisibilityTrackerTests

- (void)setUp {
    self.window = [UIWindow new];
    self.window.hidden = NO;
    
    self.containerView = [UIView new];
    [self.window addSubview:self.containerView];
    
    self.view = [UIView new];
    [self.containerView addSubview:self.view];
    
    // Advance compare date so it's not early
    self.tracker = [[IGListViewVisibilityTracker alloc] initWithView:self.view];
    self.tracker.comparedDateOverride = [self.tracker.dateCreated dateByAddingTimeInterval:self.tracker.earlyTimeInterval + 1];
}

#pragma mark - Window

- (void)test_whenOnWindow_thatVisible {
    XCTAssertEqual(self.tracker.state, IGListViewVisibilityStateMaybeVisible);
}

- (void)test_whenNoWindow_thatNotVisible {
    [self.view removeFromSuperview];
    XCTAssertEqual(self.tracker.state, IGListViewVisibilityStateNotVisible);
}

#pragma mark - Hidden

- (void)test_whenOnWindow_hidden_thatNotVisible {
    self.view.hidden = YES;
    XCTAssertEqual(self.tracker.state, IGListViewVisibilityStateNotVisible);
}

- (void)test_whenOnWindow_parentHidden_thatNotVisible {
    self.containerView.hidden = YES;
    XCTAssertEqual(self.tracker.state, IGListViewVisibilityStateNotVisible);
}

#pragma mark - Alpha

- (void)test_whenOnWindow_zeroAlpha_thatNotVisible {
    self.view.alpha = 0;
    XCTAssertEqual(self.tracker.state, IGListViewVisibilityStateNotVisible);
}

- (void)test_whenOnWindow_parentZeroAlpha_thatNotVisible {
    self.containerView.alpha = 0;
    XCTAssertEqual(self.tracker.state, IGListViewVisibilityStateNotVisible);
}

- (void)test_whenOnWindow_windowHidden_thatNotVisible {
    self.window.hidden = YES;
    XCTAssertEqual(self.tracker.state, IGListViewVisibilityStateNotVisible);
}

- (void)test_whenOnWindow_alphaVerySmall_thatNotVisible {
    self.view.alpha = FLT_EPSILON / 2;
    XCTAssertEqual(self.tracker.state, IGListViewVisibilityStateNotVisible);
}

- (void)test_whenOnWindow_alphaAtEpsilon_thatVisible {
    self.view.alpha = FLT_EPSILON;
    XCTAssertEqual(self.tracker.state, IGListViewVisibilityStateMaybeVisible);
}

#pragma mark - Early

- (void)test_whenNoWindow_andEarly_thatNotVisibleEarly {
    [self.view removeFromSuperview];

    self.tracker.earlyTimeInterval = 1.0;
    self.tracker.comparedDateOverride = self.tracker.dateCreated;

    XCTAssertEqual(self.tracker.state, IGListViewVisibilityStateNotVisibleEarly);
}

- (void)test_whenNoWindow_andEarly_withoutDateOverride_thatNotVisibleEarly {
    UIView *const newView = [UIView new];
    IGListViewVisibilityTracker *const newTracker = [[IGListViewVisibilityTracker alloc] initWithView:newView];
    newTracker.earlyTimeInterval = 100.0; // Large interval ensures we're still "early"

    // No comparedDateOverride set, so it uses [NSDate date]
    XCTAssertEqual(newTracker.state, IGListViewVisibilityStateNotVisibleEarly);
}

#pragma mark - Attached

- (void)test_whenAttachingTracker_thatReturnsTheSame {
    UIView *const view = [UIView new];
    IGListViewVisibilityTracker *const tracker1 = IGListViewVisibilityTrackerAttachedOnView(view);
    XCTAssertNotNil(tracker1);
    
    IGListViewVisibilityTracker *const tracker2 = IGListViewVisibilityTrackerAttachedOnView(view);
    XCTAssertEqual(tracker1, tracker2);
}

- (void)test_whenAttachingTracker_andViewIsNil_thatReturnsNil {
    UIView *view = [UIView new];
    view = nil;
    XCTAssertNil(IGListViewVisibilityTrackerAttachedOnView(view));
}

@end