自动生成 SwiftUI 预览的快照测试
快照生成
自动生成 SwiftUI 预览的快照测试
安装
Swift Package Manager
在 中添加 SnapshotGen 和 SnapshotTesting 作为依赖项。Package.swift
dependencies: [
.package(
url: "https://github.com/whiteio/SnapshotGen",
revision: "deeb172a353c40c2ccdb85803ffdb3ab5ac7eeeb"
),
]
将快照测试添加为测试目标中的依赖项
targets: [
.target(name: "MyApp"),
.testTarget(
name: "MyAppTests",
dependencies: [
"MyApp",
.product(name: "SnapshotGenTesting", package: "SnapshotGen"),
]
)
]
用法
命令行
swift package generate-snapshots
以下是必要的命令行参数：
--input Directory or file containing SwiftUI previews to generate snapshots for
--output Directory to store the generate preview snapshots
--testable-import-name Name of the module containing the previews (used as @testable import ___MODULENAME___)
Example:
swift package generate-snapshots --input Sources/ --output Tests/ --testable-import-name ModuleName
Excluding SwiftUI Previews
SwiftUI previews can be excluded by adding an annotation above the struct which conforms to to prevent snapshot tests being generated for it. For example:PreviewProvider
// snapshot-gen skip
struct ExampleView_Previews: PreviewProvider {
static var previews: some View {
ExampleView()
}
}
Annotations can be interleaved with documentation comments.
Troubleshooting
Due to the way images are created from SwiftUI previews the following error snapshot may be produced:
To resolve this, the preview can be set to a fixed size, e.g.
struct ExampleView_Previews: PreviewProvider {
static var previews: some View {
ExampleView()
.previewLayout(.fixed(width: 400, height: 900))
}
}
