Unit Test Migration

This example shows how to migrate from swift-snapshot-testing to preview providers. The example app contains a unit test target UnitTestMigrationTests with one snapshot test. It has been migrated by copying/pasting the file into the main app target as ExampleSnapshotTest_Migrated.swift. The test is modified by removing the XCTest/SnapshotTesting importants, changing the base class to SnapshotTest and adding the conformance to PreviewProvider.

Migrating your own tests

1. Add the file SnapshotTest.swift to your app, this does the heavy lifting of converting snapshot test function calls into previews.
2. Copy your test file from the unit test target to your application.
3. Remove imports of XCTest and SnapshotTesting.
4. Change the base class from XCTestCase to SnapshotTest and add a conformce to PreviewProvider.

Here’s a complete example of a migrated test:

import SwiftUI

// Add the conformance to `PreviewProvider` when extending `SnapshotTest`
// The `SnapshotTest` base class automatically handles turning calls to
// assertSnapshot into previews.
class ExampleSnapshotTest: SnapshotTest, PreviewProvider {

  func testContentViewSnapshot() {
    assertSnapshot(of: ContentView(), as: .image)
  }
}