Testing SpecFlow-重试失败的测试

是否有一种方法可以实现

AfterScenario

hook，以便在失败时重新运行当前测试

大概是这样的：

[AfterScenario("retry")]
public void Retry()
{
    if (ScenarioContext.Current.TestError != null)
    {
     // ?     
    }
}

---

注意：我的项目中的测试组合在有序测试中，并通过MsTest执行Specflow场景的目的是断言系统按预期运行

如果某个暂时的问题导致测试失败，那么让测试重新运行并“希望最好”并不能解决问题！偶尔测试失败不应该是预期的行为。测试应该在每次执行时给出一致的结果

可以找到一篇关于什么是好测试的好帖子，该答案还指出测试应该是：

可重复：每次测试应产生相同的结果。。每一个 时间测试不应依赖于不可控的参数

在这种情况下，测试失败是完全正确的。现在，您应该调查测试偶尔失败的确切原因

大多数情况下，测试失败是由于时间问题，例如页面加载期间不存在元素。在这个场景中，给定一个一致的测试环境（即相同的测试数据库、相同的测试浏览器、相同的网络设置），那么您将能够再次编写可重复的测试。查看关于使用WebDriverWait等待预定时间来测试预期DOM元素是否存在的答案

这个插件太棒了。我让它与nunit一起工作，他的例子是使用MS Test

它将允许您执行以下操作：

@retry:2
Scenario: Tag on scenario is preferred
Then scenario should be run 3 times

---

我希望能够重试失败的测试，但仍然在测试结果中报告为失败。这将使我能够轻松地确定代码工作的场景，但由于网络延迟等原因，这些场景也容易出现零星问题。这些故障的优先级与由于代码更改而出现的新故障的优先级不同

我使用MsTest实现了这一点，因为您可以创建一个继承自TestMethodAttribute的类

首先，我将此部分添加到csproj文件的底部，以便在生成*.feature.cs文件后但在实际生成之前调用自定义powershell脚本：

<Target Name="OverrideTestMethodAttribute" BeforeTargets="PrepareForBuild">
    <Message Text="Calling OverrideTestMethodAttribute.ps1" Importance="high" />
    <Exec Command="powershell -Command &quot;$(ProjectDir)OverrideTestMethodAttribute.ps1&quot;" />
</Target>

以及执行实际重试的IntegrationTestMethodAttribute类：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace MyCompany.MyProduct
{
    public class IntegrationTestMethodAttribute : TestMethodAttribute
    {
        public override TestResult[] Execute(ITestMethod testMethod)
        {
            TestResult[] testResults = null;
            var failedAttempts = new List<TestResult>();

            int maxAttempts = 5;
            for (int i = 0; i < maxAttempts; i++)
            {
                testResults = base.Execute(testMethod);
                Exception ex = testResults[0].TestFailureException;
                if (ex == null)
                {
                    break;
                }
                failedAttempts.AddRange(testResults);
            }

            if (failedAttempts.Any() && failedAttempts.Count != maxAttempts)
            {
                TestResult testResult = testResults[0];

                var messages = new StringBuilder();
                for (var i = 0; i < failedAttempts.Count; i++)
                {
                    var result = failedAttempts[i];
                    messages.AppendLine("");
                    messages.AppendLine("");
                    messages.AppendLine("");
                    messages.AppendLine($"Failure #{i + 1}:");
                    messages.AppendLine(result.TestFailureException.ToString());
                    messages.AppendLine("");
                    messages.AppendLine(result.TestContextMessages);
                }

                testResult.Outcome = UnitTestOutcome.Error;
                testResult.TestFailureException = new Exception($"Test failed {failedAttempts.Count} time(s), then succeeded");
                testResult.TestContextMessages = messages.ToString();
                testResult.LogError = "";
                testResult.DebugTrace = "";
                testResult.LogOutput = "";
            }
            return testResults;
        }
    }
}

使用系统；
使用System.Collections.Generic；
使用System.Linq；
使用系统文本；
使用Microsoft.VisualStudio.TestTools.UnitTesting；
名称空间MyCompany.MyProduct
{
公共类IntegrationTestMethodAttribute:TestMethodAttribute
{
公共重写TestResult[]执行（ITestMethod testMethod）
{
TestResult[]testResults=null；
var failedAttempts=新列表（）；
int=5；
对于（int i=0；i

首先让我说，我同意测试应该是稳定的，不应该重试。然而，我们并不是生活在一个理想的世界中，在一些非常特定的场景中，重试测试可能是一个有效的用例

我正在运行UI测试（对angular应用程序使用selenium），有时chromedriver会因为不清楚的原因而变得无响应。这种行为完全超出了我的控制范围，不存在有效的解决方案。我无法在SpecFlow步骤中重试此操作，因为我已经“给定”了登录到应用程序的步骤。当它在“何时”步骤中失败时，我还需要重新运行“给定”步骤。在这个场景中，我想关闭驱动程序，再次启动它，然后重新运行前面的所有步骤。最后，我为SpecFlow编写了一个定制的testrunner，可以从如下错误中恢复：

[AfterScenario("retry")]
public void Retry()
{
    if (ScenarioContext.Current.TestError != null)
    {
     // ?     
    }
}

免责声明：这不是预期用途，它可能会在任何版本的SpecFlow中中断。如果你是一个测试纯粹主义者，不要读更多

首先，我们创建一个类，使创建自定义ITestRunner变得容易（将所有方法提供为虚拟方法，以便可以重写它们）：

接下来，我们创建一个定制的testrunner，它会记住对场景的调用，并可以重新运行前面的步骤：

public class RetryTestRunner : OverrideableTestRunner
{
    /// <summary>
    /// Which exceptions to handle (default: all)
    /// </summary>
    public Predicate<Exception> HandleExceptionFilter { private get; set; } = _ => true;

    /// <summary>
    /// The action that is executed to recover
    /// </summary>
    public Action RecoverAction { private get; set; } = () => { };

    /// <summary>
    /// The maximum number of retries
    /// </summary>
    public int MaxRetries { private get; set; } = 10;

    /// <summary>
    /// The executed actions for this scenario, these need to be replayed in the case of an error
    /// </summary>
    private readonly List<(MethodInfo method, object[] args)> _previousSteps = new List<(MethodInfo method, object[] args)>();

    /// <summary>
    /// The number of the current try (to make sure we don't go over the specified limit)
    /// </summary>
    private int _currentTryNumber = 0;

    public NonSuckingTestRunner(ITestExecutionEngine engine) : base(new TestRunner(engine))
    {
    }

    public override void OnScenarioStart()
    {
        base.OnScenarioStart();

        _previousSteps.Clear();
        _currentTryNumber = 0;
    }

    public override void Given(string text, string multilineTextArg, Table tableArg, string keyword = null)
    {
        base.Given(text, multilineTextArg, tableArg, keyword);
        Checker()(text, multilineTextArg, tableArg, keyword);
    }

    public override void But(string text, string multilineTextArg, Table tableArg, string keyword = null)
    {
        base.But(text, multilineTextArg, tableArg, keyword);
        Checker()(text, multilineTextArg, tableArg, keyword);
    }

    public override void And(string text, string multilineTextArg, Table tableArg, string keyword = null)
    {
        base.And(text, multilineTextArg, tableArg, keyword);
        Checker()(text, multilineTextArg, tableArg, keyword);
    }

    public override void Then(string text, string multilineTextArg, Table tableArg, string keyword = null)
    {
        base.Then(text, multilineTextArg, tableArg, keyword);
        Checker()(text, multilineTextArg, tableArg, keyword);
    }

    public override void When(string text, string multilineTextArg, Table tableArg, string keyword = null)
    {
        base.When(text, multilineTextArg, tableArg, keyword);
        Checker()(text, multilineTextArg, tableArg, keyword);
    }

    // Use this delegate combination to make a params call possible
    // It is not possible to use a params argument and the CallerMemberName
    // in one method, so we curry the method to make it possible. #functionalprogramming
    public delegate void ParamsFunc(params object[] args);

    private ParamsFunc Checker([CallerMemberName] string method = null)
    {
        return args =>
        {
            // Record the previous step
            _previousSteps.Add((GetType().GetMethod(method), args));

            // Determine if we should retry
            if (ScenarioContext.ScenarioExecutionStatus != ScenarioExecutionStatus.TestError || !HandleExceptionFilter(ScenarioContext.TestError) || _currentTryNumber >= MaxRetries)
            {
                return;
            }

            // HACKY: Reset the test state to a non-error state
            typeof(ScenarioContext).GetProperty(nameof(ScenarioContext.ScenarioExecutionStatus)).SetValue(ScenarioContext, ScenarioExecutionStatus.OK);
            typeof(ScenarioContext).GetProperty(nameof(ScenarioContext.TestError)).SetValue(ScenarioContext, null);

            // Trigger the recovery action
            RecoverAction.Invoke();

            // Retry the steps
            _currentTryNumber++;
            var stepsToPlay = _previousSteps.ToList();
            _previousSteps.Clear();
            stepsToPlay.ForEach(s => s.method.Invoke(this, s.args));
        };
    }
}

要在AfterScenario步骤中使用它，可以向testrunner添加一个RetryScenario（）方法并调用该方法

---

作为最后一句话：当你无能为力时，将此作为最后的手段。运行不可靠的测试总比不运行任何测试好。

第二次运行它成功的条件是什么？好问题@rene！我想我的整个想法都是死胎。无论谁否决了我，请解释一下你为什么这么做

public class RetryTestRunner : OverrideableTestRunner
{
    /// <summary>
    /// Which exceptions to handle (default: all)
    /// </summary>
    public Predicate<Exception> HandleExceptionFilter { private get; set; } = _ => true;

    /// <summary>
    /// The action that is executed to recover
    /// </summary>
    public Action RecoverAction { private get; set; } = () => { };

    /// <summary>
    /// The maximum number of retries
    /// </summary>
    public int MaxRetries { private get; set; } = 10;

    /// <summary>
    /// The executed actions for this scenario, these need to be replayed in the case of an error
    /// </summary>
    private readonly List<(MethodInfo method, object[] args)> _previousSteps = new List<(MethodInfo method, object[] args)>();

    /// <summary>
    /// The number of the current try (to make sure we don't go over the specified limit)
    /// </summary>
    private int _currentTryNumber = 0;

    public NonSuckingTestRunner(ITestExecutionEngine engine) : base(new TestRunner(engine))
    {
    }

    public override void OnScenarioStart()
    {
        base.OnScenarioStart();

        _previousSteps.Clear();
        _currentTryNumber = 0;
    }

    public override void Given(string text, string multilineTextArg, Table tableArg, string keyword = null)
    {
        base.Given(text, multilineTextArg, tableArg, keyword);
        Checker()(text, multilineTextArg, tableArg, keyword);
    }

    public override void But(string text, string multilineTextArg, Table tableArg, string keyword = null)
    {
        base.But(text, multilineTextArg, tableArg, keyword);
        Checker()(text, multilineTextArg, tableArg, keyword);
    }

    public override void And(string text, string multilineTextArg, Table tableArg, string keyword = null)
    {
        base.And(text, multilineTextArg, tableArg, keyword);
        Checker()(text, multilineTextArg, tableArg, keyword);
    }

    public override void Then(string text, string multilineTextArg, Table tableArg, string keyword = null)
    {
        base.Then(text, multilineTextArg, tableArg, keyword);
        Checker()(text, multilineTextArg, tableArg, keyword);
    }

    public override void When(string text, string multilineTextArg, Table tableArg, string keyword = null)
    {
        base.When(text, multilineTextArg, tableArg, keyword);
        Checker()(text, multilineTextArg, tableArg, keyword);
    }

    // Use this delegate combination to make a params call possible
    // It is not possible to use a params argument and the CallerMemberName
    // in one method, so we curry the method to make it possible. #functionalprogramming
    public delegate void ParamsFunc(params object[] args);

    private ParamsFunc Checker([CallerMemberName] string method = null)
    {
        return args =>
        {
            // Record the previous step
            _previousSteps.Add((GetType().GetMethod(method), args));

            // Determine if we should retry
            if (ScenarioContext.ScenarioExecutionStatus != ScenarioExecutionStatus.TestError || !HandleExceptionFilter(ScenarioContext.TestError) || _currentTryNumber >= MaxRetries)
            {
                return;
            }

            // HACKY: Reset the test state to a non-error state
            typeof(ScenarioContext).GetProperty(nameof(ScenarioContext.ScenarioExecutionStatus)).SetValue(ScenarioContext, ScenarioExecutionStatus.OK);
            typeof(ScenarioContext).GetProperty(nameof(ScenarioContext.TestError)).SetValue(ScenarioContext, null);

            // Trigger the recovery action
            RecoverAction.Invoke();

            // Retry the steps
            _currentTryNumber++;
            var stepsToPlay = _previousSteps.ToList();
            _previousSteps.Clear();
            stepsToPlay.ForEach(s => s.method.Invoke(this, s.args));
        };
    }
}

 /// <summary>
/// We need this because this is the only way to configure specflow before it starts
/// </summary>
[TestClass]
public class CustomDependencyProvider : DefaultDependencyProvider
{
    [AssemblyInitialize]
    public static void AssemblyInitialize(TestContext testContext)
    {
        // Override the dependency provider of specflow
        ContainerBuilder.DefaultDependencyProvider = new CustomDependencyProvider();
        TestRunnerManager.OnTestRunStart(typeof(CustomDependencyProvider).Assembly);
    }

    [AssemblyCleanup]
    public static void AssemblyCleanup()
    {
        TestRunnerManager.OnTestRunEnd(typeof(CustomDependencyProvider).Assembly);
    }

    public override void RegisterTestThreadContainerDefaults(ObjectContainer testThreadContainer)
    {
        base.RegisterTestThreadContainerDefaults(testThreadContainer);

        // Use our own testrunner
        testThreadContainer.RegisterTypeAs<NonSuckingTestRunner, ITestRunner>();
    }
}

<PropertyGroup>
  <GenerateSpecFlowAssemblyHooksFile>false</GenerateSpecFlowAssemblyHooksFile>
</PropertyGroup>

[Binding]
public class TestInitialize
{
    private readonly RetryTestRunner _testRunner;

    public TestInitialize(ITestRunner testRunner)
    {
        _testRunner = testRunner as RetryTestRunner;
    }

    [BeforeScenario()]
    public void TestInit()
    {
        _testRunner.RecoverAction = () =>
        {
            StopDriver();
            StartDriver();
        };

        _testRunner.HandleExceptionFilter = ex => ex is WebDriverException;
    }
}