PowerShell:使用前/后 block 纠缠单元测试

Question

我正在学习使用 Pester 进行单元测试，但我在使用 Before/After block 时遇到了一个奇怪的问题。我的单元测试代码如下:

 Describe "Before/After Blocks" {

        Context "BeforeEach/AfterAll" {

            BeforeAll {
                $value = 0
                Write-Host "->Initial value is $value"
            }

            BeforeEach {
                $value++
            }

            It "value is 1" {
                $value | Should -Be 1
            }

            It "value is 2" {
                $value | Should -Be 2
            }

            It "value is 3" {
                $value | Should -Be 3
            }

            AfterAll {
                Write-Host "->Final value is $value"
            }
        }
    }

好吧，正如您在代码中看到的那样，我的目的是初始化一个变量并查看它是如何通过 BeforeEach block 递增的。这是输出:

Context BeforeEach/AfterAll

->Initial value is 0

[+] value is 1 

[+] value is 2 

[+] value is 3 

->Final value is 0

变量被初始化为 0 并且在任何 It Block 之前它正在递增，因为断言没有失败。但是 AfterAll block 说变量值为 0，即初始值，而不是我预期的 3。

为什么？

谢谢。

Answer 1

问题似乎是 AfterAll block 有它自己的范围(我同意这有点奇怪)。您可以通过使用全局变量获得您期望的结果，尽管这不是特别好的做法:

Describe "Before/After Blocks" {

    Context "BeforeEach/AfterAll" {

        BeforeAll {
            $global:value = 0
            Write-Host "->Initial value is $value"
        }

        BeforeEach {
            $global:value++
        }

        It "value is 1" {
            $global:value | Should -Be 1
        }

        It "value is 2" {
            $global:value | Should -Be 2
        }

        It "value is 3" {
            $global:value | Should -Be 3
        }

        AfterAll {
            Write-Host "->Final value is $global:value"
        }
    }
}