iOS Dev Recipes
RSS FeedGenerating dynamic test cases with XCTest
While working on the article about resizable fonts it became clear that getting a preview of every font size without needing to use the accessibility inspector was going to be a pain.
Instead, it would be great to use UI tests and dynamically re-launch the app with a different size for each variation and save a screenshot in the build results. You can see the full example in the sample app for font size testing or check out the simpler example below.
Originally, I referenced this great article by Brian Coyner from 2015, but it seemed to be out of date a bit, and I was hopeful that with some of the recent work done on XCTest it would be possible to update things just a bit.
Here's a quick example:
fileprivate let _widgetSizes: [CGFloat] = [
0.0, 1.0, 2.0, 4.0, 8.0,
]
struct WidgetExpander {
var widgetSize: CGFloat
var isValid: Bool {
return true // ;)
}
}
class WidgetExpanderTest: XCTestCase {
var widgetSize: CGFloat!
override class var defaultTestSuite: XCTestSuite {
let suite = XCTestSuite(forTestCaseClass: WidgetExpanderTest.self)
_widgetSizes.forEach { size in
// Generate a test for our specific selector
let test = WidgetExpanderTest(selector: #selector(verifyWidget))
// Each test will take the size argument and use the instance variable in the test
test.widgetSize = size
// Add it to the suite, and the defaults handle the rest
suite.addTest(test)
}
return suite
}
// NOTE: Don't name this method with "test" or it'll
// still get picked up by the automatic test case generation.
@objc func verifyWidget() {
XCTAssertTrue(WidgetExpander(size: widgetSize).isValid)
}
}