快速了解iOS单元测试


快速了解iOS单元测试

XCTestCase

进入xxUITests.m文件,会看到继承自XCTestCase:Xcode集成的一套单元测试框架

XCTestCase
The primary class for defining test cases, test methods, and performance tests.

## Overview

A test case is a group of related test methods, with optional setup and teardown before and after tests are run. See [Defining Test Cases and Test Methods](apple-reference-documentation://tc2870870) for more information.

每个测试用例在运行前都会执行setup方法(Provides an opportunity to customize initial state before a test case begins.),并且在运行后会执行teardown方法(Provides an opportunity to perform cleanup after a test case ends.)。我们可以在此时做一些初始化、销毁回收等操作。
testExample作为逻辑测试,测试逻辑是否有问题;testPerformanceExample作为性能测试,测试当前用例的性能,耗时等操作,先看一个逻辑测试的demo。

每个测试用例都要以test开头,比如testExampl

- (void)setUp {
    // Put setup code here. This method is called before the invocation of each test method in the class.
}

- (void)tearDown {
    // Put teardown code here. This method is called after the invocation of each test method in the class.
}

- (void)testExample {
    // This is an example of a functional test case.
    // Use XCTAssert and related functions to verify your tests produce the correct results.
    int a = 10;
    int b = 20;
    int c = a + b;
    XCTAssertEqual(c, 30, @"计算正确");
}

- (void)testPerformanceExample {
    // This is an example of a performance test case.
    [self measureBlock:^{
        // Put the code you want to measure the time of here.
    }];
}

在此测试用例demo运行时,当c等于30的时候直接通过,否则这里会报错!这里使用XCTAssertEqual断言来进行判断条件是否成立。

常用断言

XCTAssertEqual:Asserts that two expressions have the same value.
XCTAssertEqualObjects:Asserts that two objects are considered equal.
XCTAssertNotEqual:Asserts that two expressions do not have the same value.
XCTAssertNotEqualObjects:Asserts that two objects are not considered equal.
XCTAssertEqualWithAccuracy:Asserts that two expressions have the same value within a certain accuracy.
XCTAssertNotEqualWithAccuracy:Asserts that two expressions do not have the same value within a certain accuracy.
XCTAssertNil:Asserts that an expression is nil.
XCTAssertNotNil:Asserts that an expression is not nil.

检验平等和不平等(Testing for Equality and Inequality )

  • XCTAssertEqual(expression1, expression2, format...):当expression1不等于expression2时报错,这个测试用于C语言的标量。
  • XCTAssertEqualObjects(expression1, expression2, format...):当expression1不等于expression2时报错(或者一个对象为空,另一个不为空)。
  • XCTAssertNotEqual(expression1, expression2, format...):当expression1等于expression2时报错,这个测试用于C语言的标量。
  • XCTAssertNotEqualObjects(expression1, expression2, format...):当expression1等于expression2时报错。

在给定精度内测试是否相等

  • XCTAssertEqualWithAccuracy(expression1, expression2, accuracy, format...):当expression1和expression2之间的差别高于accuracy 将报错。这种测试适用于floats和doubles这些标量,两者之间的细微差异导致它们不完全相等,但是对所有的标量都有效。
  • XCTAssertNotEqualWithAccuracy(expression1, expression2, accuracy, format...):当expression1和expression2之间的差别低于accuracy将产生失败。这种测试适用于floats和doubles这些标量,两者之间的细微差异导致它们不完全相等,但是对所有的标量都有效。

测试一个条件是否为空

  • XCTAssertNil(expression, format...):当expression参数非nil时报错。
  • XCTAssertNotNil(expression, format...):当expression参数为nil时报错。

性能测试

//性能测试方法,通过测试block中方法执行的时间,比对设定的标准值和偏差觉得是否可以通过测试

 // Measures the performance of a block of code.
- measureBlock:
 // Measures the performance of a block of code, optionally deferring the starting point for measurement.
- measureMetrics:automaticallyStartMeasuring:forBlock:
 // Starts the measurement of performance metrics within a block of code.
 - startMeasuring
 // Ends the measurement of performance metrics within a block of code.
- stopMeasuring
// Identifies the performance metrics measured when [`measure<wbr style="margin-bottom: 0px;">Block:`](apple-reference-documentation://hcnJonuUfI) is invoked.
defaultPerformanceMetrics
 // Performance metrics that can be measured by XCTest.
XCTPerformanceMetric

- measureBlock主要是通过block内部代码块的执行时间来测试性能,通过设置baseline(基准)和stddev(标准偏差)来判断方法是否能通过性能测试。
- measureMetrics:automaticallyStartMeasuring:forBlock测量代码块的性能,可以选择推迟测量的起点。
- startMeasuring在代码块中开始性能度量。
- stopMeasuring结束代码块内的性能度量。
defaultPerformanceMetrics标识在调用measureBlock:时度量的性能指标。
XCTPerformanceMetricXCTest可以测量的性能指标。

创建异步测试期望

要创建异步测试期望,请使用下面的方便方法,或者手动创建XCTestExpectation及其子类的实例。

// Creates a new expectation with an associated description.
- expectationWithDescription:
// Creates an expectation that is fulfilled if the predicate returns YES when evaluated with the given object.
- expectationForPredicate:evaluatedWithObject:handler:
// Creates an expectation that is fulfilled when a specific [`NSNotification`](apple-reference-documentation://hcmB87CArc) is received for a given object.
- expectationForNotification:object:handler:
// Creates an expectation that uses Key Value Observing to observe a value until it matches an expected value.
- keyValueObservingExpectationForObject:keyPath:expectedValue:
// Creates an expectation that uses Key Value Observing to observe a value and respond to changes in that value by calling a provided handler.
- keyValueObservingExpectationForObject:keyPath:handler:

- expectationWithDescription:创建带有关联描述的新期望,比如操作出错的原因描述。
- expectationForPredicate:evaluatedWithObject:handler:创建一个期望,如果predicate在对给定对象进行计算时返回YES,则该期望将被满足。
- expectationForNotification:object:handler:创建期望,该期望在接收到给定对象的特定NSNotification时被实现。该方法监听一个通知,如果在规定时间内正确收到通知则测试通过。
- keyValueObservingExpectationForObject:keyPath:expectedValue:创建一个期望,该期望使用键值观察来观察一个值,直到它与期望的值匹配为止。
- keyValueObservingExpectationForObject:keyPath:handler:创建一个期望,该期望使用键值观察来观察值,并通过handler来响应该值中的更改。

等待的期望

可以使用下面的方法实现等待异步测试期望,或者创建XCTWaiter的实例。

// Waits on a group of expectations for up to the specified timeout.
- waitForExpectations:timeout:
// Waits on an array of expectations and specifies whether they must be fulfilled in the given order.
- waitForExpectations:timeout:enforceOrder:
// Waits until all expectations are fulfilled or the timeout is reached.
- waitForExpectationsWithTimeout:handler:
// A block to be called when a call to waitForExpectationsWithTimeout:handler: has all of its expectations fulfilled, or times out.
XCWaitCompletionHandler
// Error codes for errors that can occur while waiting for expectations to be fulfilled.
XCTestErrorCode
// Error domain for errors that can occur while waiting for expectations to be fulfilled.
XCTestErrorDomain

- waitForExpectations:timeout:等待一组期望,直到指定的超时。
- waitForExpectations:timeout:enforceOrder:等待一系列期望,并指定它们是否必须按照给定的顺序实现。
- waitForExpectationsWithTimeout:handler:等待,直到所有期望都满足或达到超时,执行handler。设置延迟时间(秒),如果没有满足测试条件就报错。
XCWaitCompletionHandler:当waitForExpectationsWithTimeout:handler:的调用完成了所有的期望或超时时的回调。
XCTestErrorCode:在等待期望实现时可能发生的错误的错误代码。
XCTestErrorDomain:在等待期望实现时可能发生的错误的错误域。

该文章为记录本人的学习路程,也希望能够帮助大家,知识共享,共同成长,共同进步!!!


文章作者: Vincent
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