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Helper Code for Snapshot Testing
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import AccessibilitySnapshot | |
import SnapshotTesting | |
import SwiftUI | |
import XCTest | |
extension Snapshotting where Value == UIViewController, Format == UIImage { | |
fileprivate static func standardImage( | |
on viewImageConfig: ViewImageConfig, | |
perceptualPrecision: Float = 0.98, | |
precision: Float = 0.995 | |
) -> Snapshotting { | |
.image( | |
drawHierarchyInKeyWindow: true, | |
precision: precision, | |
perceptualPrecision: perceptualPrecision, | |
size: viewImageConfig.size | |
) | |
} | |
fileprivate static func standardVoiceOverAccessibilityImage(on viewImageConfig: ViewImageConfig) -> Snapshotting { | |
.impreciseAccessibilityImage( | |
drawHierarchyInKeyWindow: true, | |
precision: 0.995, | |
perceptualPrecision: 0.98 | |
) | |
} | |
} | |
extension XCTest { | |
// https://github.com/pointfreeco/swift-snapshot-testing/discussions/553#discussioncomment-3807207 | |
private static var xcodeCloudFilePath: StaticString { | |
"/Volumes/workspace/repository/ci_scripts/SnapshotTests.swift" | |
} | |
private static var isCIEnvironment: Bool { | |
ProcessInfo.processInfo.environment["CI"] == "TRUE" | |
} | |
/// Creates snapshots in a variety of different environments at the screen size of an iPhone SE (by | |
/// default). | |
/// This method ensures that tests are running on a the proper device or simulator | |
/// and OS version. | |
/// | |
/// Environments used for these snapshots: | |
/// * Light Mode | |
/// * Dark Mode | |
/// * All Dynamic Type Sizes | |
/// * VoiceOver Accessibility | |
/// | |
/// - Parameters: | |
/// - view: The SwiftUI `View` to snapshot. | |
/// - createThrowaway: Create 1px by 1px "throwaway" image to allow dependencies time to get | |
/// setup. Defaults to `false`. | |
/// - snapshotDeviceModelName: The device model name used when recording snapshots. | |
/// Defaults to `"iPhone 15 Pro"`. The test will fail if snapshots are recorded with a different | |
/// device. | |
/// - snapshotDeviceOSVersions: A dictionary of the OS versions used for snapshots. Defaults | |
/// to: ["iOS": "17.0.1", "macOS": "14.0", "tvOS": "17.0", "visionOS": "1.0", "watchOS": "10.0"]. The test will fail | |
/// if snapshots are recorded with a different version. | |
/// - viewImageConfig: The `ViewImageConfig` for the snapshot which will determine the size of the rendered snapshot. | |
/// Defaults to `.iPhoneSe`. | |
/// - xcodeCloudFilePath: A `StaticString` describing the path that will be used when | |
/// running these tests on Xcode Cloud. Defaults to `"/Volumes/workspace/repository/ci_scripts/SnapshotTests.swift"`. If your | |
/// tests are in a Swift file with a name other than "SnapshotTests.swift" you will need to provide this | |
/// same `StaticString` but with your test file's name in place of "SnapshotTests.swift". | |
/// - file: The file in which failure occurred. Defaults to the file name of the test case in which this function was called. | |
/// - testName: The name of the test in which failure occurred. Defaults to the function name of the test case in which this function was called. | |
/// - line: The line number on which failure occurred. Defaults to the line number on which this function was called. | |
func assertStandardSnapshots( | |
content: some View, | |
named name: String, | |
createThrowaway: Bool = false, | |
snapshotDeviceModelName: String = "iPhone 15 Pro", | |
snapshotDeviceOSVersions: [String: String] = [ | |
"iOS": "17.0.1", | |
"macOS": "14.0", | |
"tvOS": "17.0", | |
"visionOS": "1.0", | |
"watchOS": "10.0" | |
], | |
viewImageConfig: ViewImageConfig = .iPhoneSe, | |
xcodeCloudFilePath: StaticString = xcodeCloudFilePath, | |
file: StaticString = #file, | |
testName: String = #function, | |
line: UInt = #line | |
) { | |
guard UIDevice.modelName == snapshotDeviceModelName else { | |
XCTFail( | |
"Running in a \(UIDevice.modelName) simulator instead of the required \(snapshotDeviceModelName) simulator.", | |
file: file, | |
line: line | |
) | |
return | |
} | |
let snapshotDeviceOSVersion: String | |
#if os(iOS) | |
guard let version = snapshotDeviceOSVersions["iOS"] else { | |
XCTFail( | |
"iOS version not provided.", | |
file: file, | |
line: line | |
) | |
return | |
} | |
snapshotDeviceOSVersion = "\(version)" | |
#elseif os(macOS) | |
guard let version = snapshotDeviceOSVersions["macOS"] else { | |
XCTFail( | |
"macOS version not provided.", | |
file: file, | |
line: line | |
) | |
return | |
} | |
snapshotDeviceOSVersion = "\(version)" | |
#elseif os(tvOS) | |
guard let version = snapshotDeviceOSVersions["tvOS"] else { | |
XCTFail( | |
"tvOS version not provided.", | |
file: file, | |
line: line | |
) | |
return | |
} | |
snapshotDeviceOSVersion = "\(version)" | |
#elseif os(visionOS) | |
guard let version = snapshotDeviceOSVersions["visionOS"] else { | |
XCTFail( | |
"visionOS version not provided.", | |
file: file, | |
line: line | |
) | |
return | |
} | |
snapshotDeviceOSVersion = "\(version)" | |
#elseif os(watchOS) | |
guard let version = snapshotDeviceOSVersions["watchOS"] else { | |
XCTFail( | |
"watchOS version not provided.", | |
file: file, | |
line: line | |
) | |
return | |
} | |
snapshotDeviceOSVersion = "\(version)" | |
#endif | |
guard UIDevice.current.systemVersion == "\(snapshotDeviceOSVersion)" else { | |
XCTFail( | |
"Running with OS version \(UIDevice.current.systemVersion) instead of the required OS version \(snapshotDeviceOSVersion).", | |
file: file, | |
line: line | |
) | |
return | |
} | |
if Locale.preferredLanguages.first != "en-US" | |
&& Locale.preferredLanguages.first != "en" { | |
XCTFail( | |
""" | |
Running on a simulator with its first preferred language set to \ | |
something other than English (US) may cause the snapshots to be rendered \ | |
differently. Please set English (US) as the simulator's first preferred \ | |
language (Settings > General > Language & Region). First preferred \ | |
language: \(Locale.preferredLanguages.first ?? "Unknown") | |
""", | |
file: file, | |
line: line | |
) | |
return | |
} | |
if Locale.preferredLanguages.contains(where: { | |
$0.contains("ar") || $0.contains("hy") | |
}) { | |
XCTFail( | |
""" | |
Running on a simulator with Arabic or Armenian in its preferred \ | |
languages which will cause the snapshots to be rendered differently. \ | |
Please remove Arabic and/or Armenian from the simulator's preferred \ | |
languages (Settings > General > Language & Region). | |
""", | |
file: file, | |
line: line | |
) | |
return | |
} | |
let filePath: StaticString | |
if Self.isCIEnvironment { | |
filePath = xcodeCloudFilePath | |
} else { | |
filePath = file | |
} | |
if createThrowaway { | |
let viewController = UIHostingController( | |
rootView: content | |
.transaction { $0.animation = nil } | |
) | |
let screenScale = max(1, UIScreen.main.scale) | |
assertSnapshot( | |
matching: viewController, | |
as: .standardImage( | |
on: ViewImageConfig( | |
size: CGSize( | |
width: 1/screenScale, | |
height: 1/screenScale | |
) | |
), | |
perceptualPrecision: 0.0, | |
precision: 0.0 | |
), | |
named: "\(name) - Throwaway", | |
file: filePath, | |
testName: testName, | |
line: line | |
) | |
} | |
for colorScheme in ColorScheme.allCases { | |
let viewController = UIHostingController( | |
rootView: content | |
.transaction { $0.animation = nil } | |
.background(colorScheme == .light ? Color.white : Color.black) | |
.environment(\.colorScheme, colorScheme) | |
) | |
viewController.view.backgroundColor = colorScheme == .light ? .white : .black | |
assertSnapshot( | |
matching: viewController, | |
as: .wait(for: 0.1, on: .standardImage(on: viewImageConfig)), | |
named: "\(name) - Color Scheme: \(colorScheme)", | |
file: filePath, | |
testName: testName, | |
line: line | |
) | |
} | |
for size in DynamicTypeSize.allCases { | |
let viewController = UIHostingController( | |
rootView: content | |
.transaction { $0.animation = nil } | |
.environment(\.dynamicTypeSize, size) | |
) | |
assertSnapshot( | |
matching: viewController, | |
as: .wait(for: 0.1, on: .standardImage(on: viewImageConfig)), | |
named: "\(name) - Dynamic Type: \(size)", | |
file: filePath, | |
testName: testName, | |
line: line | |
) | |
} | |
do { | |
let viewController = UIHostingController( | |
rootView: content | |
.transaction { $0.animation = nil } | |
) | |
viewController.view.frame = UIScreen.main.bounds | |
assertSnapshot( | |
matching: viewController, | |
as: .wait(for: 0.1, on: .standardVoiceOverAccessibilityImage(on: viewImageConfig)), | |
named: "\(name) - VoiceOver Accessibility", | |
file: filePath, | |
testName: testName, | |
line: line | |
) | |
} | |
} | |
} |
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