11 April 2024 Leave a comment Tech-Help
Introduction
When conducting UI tests in Xcode, it’s essential to have the ability to pass and access launch arguments and environment variables. This can be crucial for testing different application states and configurations. In this guide, we’ll explore how to properly set and retrieve these parameters within your UI tests and application code.
Setting Launch Arguments and Environment Variables
To set up your UI tests with specific launch arguments or environment variables, you’ll need to modify the XCUIApplication instance within your test’s setUp() method. Here’s how you can do it:
let app = XCUIApplication()
app.launchArguments.append("SNAPSHOT")
app.launchEnvironment["testenv"] = "testenvValue"
app.launch()
This code snippet demonstrates how to add a launch argument “SNAPSHOT” and set an environment variable “testenv” with the value “testenvValue”.
Accessing Arguments and Environment Variables in Your App
Once you’ve set the launch arguments and environment variables, you can access them in your app’s code. Depending on your version of Swift, you’ll use different syntax:
Swift 2.x:
if NSProcessInfo.processInfo().arguments.contains("SNAPSHOT") {
// Do snapshot setup
}
Swift 3.0 and later:
if ProcessInfo.processInfo.arguments.contains("SNAPSHOT") {
// Do snapshot setup
}
For environment variables, replace arguments with environment and access the variables similarly:
let environmentVariables = ProcessInfo.processInfo.environment
if let testEnvValue = environmentVariables["testenv"] {
// Use testEnvValue here
}
Alternative: Using UserDefaults
Launch arguments passed to XCUIApplication.launchArguments are also accessible from UserDefaults. This is particularly useful for feature toggles during testing:
let app = XCUIApplication()
app.launchArguments.append("-ToggleFeatureOne")
app.launchArguments.append("true")
app.launch()
Then, in your app:
let featureOneEnabled = UserDefaults.standard.bool(forKey: "ToggleFeatureOne") // returns true
This method aligns with how Xcode schemes pass arguments on launch, and it’s documented under the Preferences and Settings Programming Guide.
Best Practices
To prevent typos and errors, it’s a good practice to encapsulate argument keys within an extension or enumeration. For instance:
extension ProcessInfo {
var isUITesting: Bool {
return arguments.contains("isUITesting")
}
}
With this extension, you can easily check if UI testing is in progress:
if ProcessInfo.processInfo.isUITesting {
// UITesting specific behavior
}
Remember to set the arguments before launching the app, as changes made after the launch will only take effect in subsequent executions.
Conclusion
Properly setting and retrieving launch arguments and environment variables can greatly enhance the effectiveness of your UI tests in Xcode. By following the methods outlined in this guide, you can ensure that your tests run with the necessary configurations and that your app behaves as expected under different conditions.
