powershell - 我如何通过 Powershell Pester 测试 ThrowTerminatingError

Question

我如何通过 Powershell Pester 测试 ThrowTerminatingError？

catch
{
    $PSCmdlet.ThrowTerminatingError( $PSItem )
}

输出:

Missed command:

File                  Class Function          Line Command
----                  ----- --------          ---- -------
Test-ServerOnline.ps1       Test-ServerOnline   50 $PSCmdlet.ThrowTerminatingError( $PSItem )

Answer 1

为了在 Pester 测试中捕获终止错误(异常):

• 您必须将输入命令包含在脚本 block ( { ... } )

• 并测试
  Should -Throw 是否出现/未出现此类错误/Should -Not -Throw

注意:如果您也想以这种方式处理非终止错误，Should -Throw 不处理:

• 如果输入命令调用cmdlet/高级函数，添加常用参数-ErrorAction Stop到它，这将(第一个)非终止错误提升为(脚本)终止(致命)错误。

• 否则，设置$ErrorActionPreference = 'Stop'作为第一个语句在脚本 block 中。

---

示例:

^{注意:为简洁起见，以下片段不是完整的 Pester 测试，仅调用 Pester Should命令；但是，您可以按原样调用它们，在这种情况下，没有输出 就意味着测试成功。有关完整示例，请参阅底部部分。}

# Note the { ... } around the command.
{ 1 / 0 } | Should -Throw

上面的测试通过了，因为1 / 0创建一个语句终止错误，这是与 $PSCmdlet.ThrowTerminatingError() 相同的错误类型产生。

非终止错误升级为终止错误 -ErrorAction Stop

# Note: Without -ErrorAction Stop, the test would fail, because
#       not finding a file is a non-terminating error.
{ Get-Item NoSuchFile -ErrorAction Stop } | Should -Throw

此外，您可以测试特定的错误ID，使用 -ErrorId 参数:

{ 1 / 0 } | Should -Throw -ErrorId RuntimeException

上面的测试通过了，因为用1 / 0触发的语句终止错误产生的错误记录(也记录在自动 $Error 变量中)，有一个 .FullyQualifiedErrorId RuntimeException 的值(之后用 $Error[0].FullyQualifiedErrorId 验证)。

注意: -ErrorId执行文字子串匹配，因此 -ErrorId Runtime在上面的命令中也会起作用。

或者，您可以测试特定异常类型，使用 -ExceptionType 参数:

{ 1 / 0 } | Should -Throw -ExceptionType System.Management.Automation.RuntimeException

请注意，您必须传递完整类型名称；省略 System.组件(PowerShell 通常允许)不被-ExceptionType 识别.

要识别与最近错误关联的异常类型，请使用 $Error[0].Exception.GetType().FullName

---

完整示例:

将以下内容存储在 *.tests.ps1 中文件并直接或通过 Invoke-Pester 调用它.
所有这些测试都应该通过。

Describe "Error-handling tests" {

  BeforeAll {
    # Define an advanced function that generates a terminating error.
    function Get-FooTerminating {
      [CmdletBinding()]
      param()
      # When invoked by Pester, $PSCmdlet.ThrowTerminatingError()
      # would have the same effect here, but note that $PSCmdlet.ThrowTerminatingError()
      # creates a *statement*-terminating error, whereas Throw creates a more
      # severe *script*-terminating (thread-terminating) error.
      Throw "me for a loop"
    }
    
    # Define an advanced function that generates a non-terminating error.
    function Get-FooNonTerminating {
      [CmdletBinding()]
      param()
      Write-Error "Something went mildly wrong."
    }

  }

  It "A terminating error throws." {
    { Get-FooTerminating } | Should -Throw
  }

  It "A non-terminating error doesn't throw." {
    # Note: Non-terminating errors are *passed through*, so
    #       we silence them with 2>$null here.
    { Get-FooNonTerminating 2>$null } | Should -Not -Throw
  }

  It "A non-terminating error promoted to a terminating one does throw." {
    { Get-FooNonTerminating -ErrorAction Stop } | Should -Throw
  }

  It "A fully qualified error ID can be tested for." {
    # Test for a (substring of) the error record's .FullyQualifiedErrorId 
    { NoSuchCommand } | Should -Throw -ErrorId CommandNotFound
  }

  It "A specific exception type can be tested for." {
    # Note the need to specify the type name *in full*, including the
    # 'System.' part
    { NoSuchCommand } | Should -Throw -ExceptionType System.Management.Automation.CommandNotFoundException
  }


}