Waitforexpectationswithtimeout handler

Waitforexpectationswithtimeout handler

Posted: NMN Date of post: 15.06.2017

XCTestExpectation and performance tests.

waitforexpectationswithtimeout handler

Most Xcode project templates now support testing out-of-the-box. Xcode unit tests are contained within an XCTestCase subclass. By convention, each XCTestCase subclass encapsulates a particular set of concerns, such as a feature, use case, or flow of an application.

Dividing up tests logically across a manageable number of test cases makes a huge difference as codebases grow and evolve. Since XCTestCase is not intended to be initialized directly from within a test case definition, shared properties initialized in setUp are declared as optional var s in Swift. XCTest comes with a number of built-in assertions, but one could narrow them down to just a few essentials:.

To be entirely reductionist, all of the XCTest assertions come down to a single, base assertion:. If the expression evaluates to true , the test passes.

Asynchronous Testing With Xcode 6

Otherwise, the test fails, printing the format ted message. Although a developer could get away with only using XCTAssert , the following helper assertions provide some useful semantics to help clarify what exactly is being tested. When possible, use the most specific assertion available, falling back to XCTAssert only in cases where it better expresses the intent.

When testing whether two values are equal, use XCTAssert[Not]Equal for scalar values and XCTAssert[Not]EqualObjects for objects:. XCTAssert[Not]EqualObjects is not necessary in Swift, since there is no distinction between scalars and objects. When specifically testing whether two Double , Float , or other floating-point values are equal, use XCTAssert[Not]EqualWithAccuracy , to account for any issues with floating point accuracy:.

XCTFail is most commonly used to denote a placeholder for a test that should be made to pass. It is also useful for handling error cases already accounted by other flow control structures, such as the else clause of an if statement testing for success. New in Xcode 6 is the ability to benchmark the performance of code:.

ios - waitForExpectationsWithTimeout crashes - Stack Overflow

The measured block is executed ten times and the test output shows the average execution time as well as individual run times and standard deviation:. Performance tests help establish a per-device baseline of performance for hot code paths and will fail if execution time becomes significantly slower.

Sprinkle them into your test cases to ensure that significant algorithms and procedures remain performant as time goes on. Perhaps the most exciting feature added in Xcode 6 is built-in support for asynchronous testing, with the XCTestExpectation class.

Now, tests can wait for a specified length of time for certain conditions to be satisfied, without resorting to complicated GCD incantations. To make a test asynchronous, first create an expectation with expectation description: Then, at the bottom of the method, add the waitForExpectations timeout: Now, the only remaining step is to fulfill that expecation in the relevant callback of the asynchronous method being tested:.

Always call fulfill at the end of the asynchronous callback—fulfilling the expectation earlier can set up a race condition where the run loop may exit before completing the test. If the test has more than one expectation, it will not pass unless each expectation executes fulfill within the timeout specified in waitForExpectations timeout: With first-class support for asynchronous testing, Xcode 6 seems to have fulfilled all of the needs of a modern test-driven developer.

Well, perhaps save for one: Mocking can be a useful technique for isolating and controlling behavior in systems that, for reasons of complexity, non-determinism, or performance constraints, do not usually lend themselves to testing. Examples include simulating specific networking interactions, intensive database queries, or inducing states that might emerge under a particular race condition.

There are a couple of open source libraries for creating mock objects and stubbing method calls, but these libraries largely rely on Objective-C runtime manipulation, something that is not currently possible with Swift.

In Swift, classes can be declared within the definition of a function, allowing for mock objects to be extremely self-contained. Just declare a mock inner class, and then override any necessary methods:. That is to say, there are no particularly compelling reasons to use any additional abstractions in order to provide acceptable test coverage for the vast majority apps and libraries.

Except in extreme cases that require extensive stubbing, mocking, or other exotic test constructs, XCTest assertions, expectations, and performance measurements should be sufficient.

Issues and pull requests are always welcome — NSHipster is made better by readers like you. This article uses Swift version 3.

waitforexpectationswithtimeout handler

Find status information for all articles on the status page. Mattt Thompson mattt is a writer and developer from the Rustbelt. Although we still have a few months to wait before we can ship apps in Swift, there is already a proliferation of open source projects built with this new language.

One such project is Alamofire. NSHipster or on GitHub. XCTestCase Xcode unit tests are contained within an XCTestCase subclass. This method is called before the invocation of each test method in the class.

How to Use iOS Expectations to Test Async Functions Without a Callback Method - Savvy Apps

This method is called after the invocation of each test method in the class. XCTAssert expression , message. XCTAssert expression , format XCTAssertTrue expression , message XCTAssertFalse expression , message. XCTAssertTrue expression , format XCTAssertEqual expression1 , expression2 , message XCTAssertNotEqual expression1 , expression2 , message. XCTAssertEqual expression1 , expression2 , format XCTAssertEqualWithAccuracy expression1 , expression2 , accuracy , message XCTAssertNotEqualWithAccuracy expression1 , expression2 , accuracy , message.

XCTAssertEqualWithAccuracy expression1 , expression2 , accuracy , format XCTAssertNil expression , message XCTAssertNotNil expression , message. XCTAssertNil expression , format Written by Mattt Thompson Mattt Thompson mattt is a writer and developer from the Rustbelt. Next Article Alamofire Although we still have a few months to wait before we can ship apps in Swift, there is already a proliferation of open source projects built with this new language.

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