Pesterでカスタムアサーションを行うサンプル(Pester 4.0.5以前)

## Invoke-PesterCustomAssertionSample.ps1
# 参考 http://kamranicus.com/blog/2016/08/17/posh-pester-extend-custom-assertions/
# Pester 3.4.0 で検証済み
Import-Module Pester

# Pester + 動詞 の名前を持つ3つの関数を作る必要がある
# 1. Pester[動詞]
function PesterBeHash($Value, $Expected) {
    if (-not ($Value -is [Hashtable] -and $Expected -is [Hashtable])) {
        return $Value -eq $Expected
    }
    if ($Value.Keys.Count -ne $Expected.Keys.Count) {
        return $false
    }
    foreach ($key in $Value.Keys) {
        if ($Value[$key] -ne $Expected[$key]) {
            return $false
        }
    }
    return $true
}
# 2. Pester[動詞]FailureMessage
Function PesterBeHashFailureMessage($Value, $Expected) {
    $e = ""
    if ($Expected -is [Hashtable]) {
        foreach ($key in $Expected.Keys) {
            if ($e -ne "") { $e += ";" }
            $e += "{0}={1}" -f $key, $Expected[$key]
        }
    } else {
        $e = "[{0}] {1}" -f ($Expected.GetType()), [string]$Expected
    }
    $v = ""
    if ($Value -is [Hashtable]) {
        foreach ($key in $Value.Keys) {
            if ($v -ne "") { $v += ";" }
            $v += "{0}={1}" -f $key, $Value[$key]
        }
    } else {
        $v = "[{0}] {1}" -f ($Value.GetType()), [string]$Value
    }
    return "Expected: {0}`nBut was: {1}" -f $e, $v
}
# 3. NotPester[動詞]FailureMessage
Function NotPesterBeHashFailureMessage($Value, $Expected) {
    return PesterBeHashFailureMessage -Value $Value -Expected $Expected
}

Describe "カスタムアサーションのサンプル" {
    # Should Be ではハッシュは比較できない
    It "通常のアサーションで失敗する例" {
        @{ Name = "田中"; Salary = 300 } | Should Be @{ Name = "田中"; Salary = 300 }
    }

    # カスタムアサーションでハッシュを比較してみる
    It "カスタムアサーション成功例" {
        @{ Name = "田中"; Salary = 300 } | Should BeHash @{ Name = "田中"; Salary = 300 }
    }
    It "カスタムアサーション失敗例" {
        @{ Name = "鈴木"; Salary = 300 } | Should BeHash @{ Name = "田中"; Salary = 300 }
    }
}