为什么当我测试某个方法引发异常而该方法引发异常时，测试是否停止？ [英] Why, when I am testing that a method throws an exception and the method throw an exception, does the test stop?

问题描述

我有一个单元测试，用于测试在条件存在且<$ c时，方法是否引发异常$ c>方法确实按预期引发异常。

I have a unit test that tests if method throws an exception when condition is present, and method does throws exception as expected.

- (void)testMethodThrowsWhenConditionIsPresent {
    XCTAssertThrows([Foo methodWithCondition: condition], @"Condition is true, method should throw exception");
}

以下是例外来源：

- (void)methodWithCondition:(someType)condition {
    if (condition) {
        [NSException raise: @"condition is true!" format: @"condition is true!"];
    }
}

为什么测试在行中停止，例外是抛出？测试没有继续，它在那行停止，当我期望它继续并从 XCTAssertThrows（） 1 时c>，使测试成功。相反，测试通过Xcode停止，使我进入抛出的行，并带有绿色的线程1：断点1.1，并且调试器出现在控制台中。

Why does the test stop at the line the exception is thrown? The test does not go on, it stops at that line, when I expect it to continue and return 1 from XCTAssertThrows(), making the test succeed. The test instead stops with Xcode bringing me to the line it was thrown, with a green `Thread 1: breakpoint 1.1' and the debugger appearing in the console.

推荐答案

为什么在执行被抛出时测试会停止？

因为您有一个断点，它会停止执行。

"Why does the test stop when the execution is thrown?"

Because you have a breakpoint, which stops execution.

因为您有未处理的异常。未处理的异常会导致您的程序崩溃。

Because you have an unhandled exception. Unhandled exceptions cause your program to crash.

这个问题的简单答案是不抛出异常。在其他编程语言（如Java）中，这是完全标准的。但是在Objective-C中，我们实际上并没有例外。在Objective-C中，应保存TRULY异常行为的异常。

The easy answer to this question is to simply NOT throw an exception. In other programming languages, like Java, this is perfectly standard. But in Objective-C, we don't really do exceptions. In Objective-C, exceptions should be saved for TRULY exceptional behavior.

话虽如此，强烈建议您找到另一种方式来处理您所要解决的问题重新尝试处理，这是您在Objective-C中处理异常的方式：

With that said, and a strong suggestion for you to find another way to handle whatever it is you're trying to handle, this is how you handle an exception in Objective-C:

@try {
    // code that could throw an exception
}

@catch (NSException *e) {
    // handle the exception...
}

@finally {
    // post try-catch code, executed every time
}

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