Adds draft caching mechanism

PSKoans/Init/InitializeCache.ps1

@@ -0,0 +1,9 @@
+if (-not (Test-Path -Path $Script:CachePath)) {
+    New-Item -Path $Script:CachePath -ItemType Directory > $null
+}
+
+$Script:KoanResultCache = @{}
+
+foreach ($cacheItem in Get-ChildItem $Script:CachePath -Filter *.xml) {
+    $Script:KoanResultCache[$cacheItem.BaseName] = Import-Clixml -Path $cacheItem.FullName
+}

PSKoans/PSKoans.psm1

@@ -15,6 +15,7 @@
 
 $script:ModuleRoot = $PSScriptRoot
 $script:ConfigPath = '~/.config/PSKoans/config.json'
+$script:CachePath = '~/.config/PSKoans/cache'
 $script:DefaultSettings = @{
     KoanLocation = Resolve-Path -Path '~' | Join-Path -ChildPath 'PSKoans'
     Editor       = 'code'

PSKoans/Private/Add-KoanCachedResult.ps1

@@ -0,0 +1,46 @@
+function Add-KoanCachedResult {
+    <#
+    .SYNOPSIS
+        Add an entry to the koan cache.
+
+    .DESCRIPTION
+        Cache the results of running tests for this koan. This avoids the overhead of repeatedly running pester on unchanged content.
+
+    .PARAMETER Path
+        The path to the koans test file.
+
+    .PARAMETER PesterTests
+        The result of running tests against the file created by the Invoke-Koan command.
+    #>
+
+    [CmdletBinding()]
+    param (
+        [Parameter(Mandatory)]
+        [string]
+        $Path,
+
+        [Parameter(Mandatory)]
+        [object]
+        $Result
+    )
+
+    $currentHash = (Get-FileHash -Path $Path).Hash
+    $cacheEntryName = [System.IO.Path]::GetFileNameWithoutExtension($Path)
+
+    if ($Script:KoanResultCache.Contains($cacheEntryName) -and $currentHash -eq $Script:KoanResultCache[$cacheEntryName]['Hash']) {
+        # No work to do for this file. Return immediately.
+        return
+    }
+
+    $cacheItemPath = Join-Path -Path $Script:CachePath -ChildPath (
+        '{0}.xml' -f [System.IO.Path]::GetFileNameWithoutExtension($Path)
+    )
+
+    $cacheEntry = @{
+        Hash   = $currentHash
+        Result = $Result
+    }
+    $cacheEntry | Export-CliXml -Path $cacheItemPath -Depth 5
+
+    $Script:KoanResultCache[$cacheEntryName] = $cacheEntry
+}

PSKoans/Private/Get-KoanCachedResult.ps1

@@ -0,0 +1,30 @@
+function Get-KoanCachedResult {
+    <#
+    .SYNOPSIS
+        Add an entry to the koan cache.
+
+    .DESCRIPTION
+        Cache the results of running tests for this koan. This avoids the overhead of repeatedly running pester on unchanged content.
+
+    .PARAMETER Path
+        The path to the koans test file.
+    #>
+
+    [CmdletBinding()]
+    param (
+        [Parameter(Mandatory)]
+        [string]
+        $Path
+    )
+
+    $cacheEntryName = [System.IO.Path]::GetFileNameWithoutExtension($Path)
+
+    if ($Script:KoanResultCache.ContainsKey($cacheEntryName)) {
+        $currentHash = (Get-FileHash -Path $Path).Hash
+        $cacheEntry = $Script:KoanResultCache[$cacheEntryName]
+
+        if ($currentHash -eq $cacheEntry['Hash']) {
+            $cacheEntry['Result']
+        }
+    }
+}

PSKoans/Private/Invoke-Koan.ps1

@@ -31,6 +31,11 @@
         }
     }
     end {
+        $CachedResult = Get-KoanCachedResult -Path $ParameterSplat['Script']
+        if ($CachedResult) {
+            return $CachedResult
+        }
+
         try {
             $Requirements = [System.Management.Automation.Language.Parser]::ParseFile(
                 $ParameterSplat.Script,
@@ -73,6 +78,7 @@
 
             $Status = $ps.BeginInvoke()
 
+            # Wait for the runspace in PS to support use of Control+C
             do { Start-Sleep -Milliseconds 100 } until ($Status.IsCompleted)
 
             $Result = $ps.EndInvoke($Status)
@@ -82,6 +88,9 @@
                 foreach ($errorItem in $ps.Streams.Error) {
                     $PSCmdlet.WriteError($errorItem)
                 }
+            } else {
+                # Never cache when errors are raised during the pester run
+                Add-KoanCachedResult -Path $ParameterSplat['Script'] -Result $Result
             }
 
             $Result

PSKoans/Private/Measure-Koan.ps1

@@ -39,7 +39,7 @@
         ) -join [System.IO.Path]::PathSeparator
     }
     process {
-        Write-Verbose "Discovering koans in [$($KoanInfo.Name -join '], [')]"
+        Write-Verbose "Discovering koans in [$($KoanInfo.Path -join '], [')]"
 
         $Result = & (Get-Module Pester) {
             [CmdletBinding()]

PSKoans/Private/New-KoanRunspace.ps1

@@ -26,12 +26,17 @@ function New-KoanRunspace {
 
     try {
         $script = {
-            param( $PSKoansPath )
+            param(
+                $PesterPath,
+                $PSKoansPath
+            )
 
+            Get-Module $PesterPath -ListAvailable | Import-Module
             Get-Module $PSKoansPath -ListAvailable | Import-Module
         }
 
         $ps.AddScript($script) > $null
+        $ps.AddParameter('PesterPath', (Get-Module Pester).ModuleBase) > $null
         $ps.AddParameter('PSKoansPath', $MyInvocation.MyCommand.Module.ModuleBase) > $null
         $ps.Invoke() > $null
 

Start-DebugSession.ps1

@@ -6,6 +6,10 @@ $env:PSModulePath = $(
 ) -join [System.IO.Path]::PathSeparator
 
 & $PSScriptRoot/PSKoans.ezformat.ps1
+
+$pester = Get-Module pester -ListAvailable | Where-Object Version -eq '5.0.2'
+
+Import-Module (Join-Path -Path $pester.ModuleBase -ChildPath 'pester.psd1')
 Import-Module $PSScriptRoot/PSKoans
 
-### Enter code to test below
+### Enter code to test here

Tests/Functions/Private/Add-KoanCachedResult.Tests.ps1

@@ -0,0 +1,38 @@
+#Requires -Modules PSKoans
+
+Describe 'Add-KoanCachedResult' {
+    BeforeAll {
+        Mock 'Get-FileHash' {
+            [PSCustomObject]@{
+                Hash = 'abcdef'
+            }
+        }
+        Mock 'Export-CliXml'
+    }
+
+    It 'adds an entry to the cache when the entry does not exist' {
+        InModuleScope -ModuleName 'PSKoans' {
+            $Script:KoanResultCache = @{}
+
+            Add-KoanCachedResult -Path 'AboutAssertions.Koans.ps1' -Result 'Result'
+        }
+
+        Should -Invoke 'Get-FileHash'
+        Should -Invoke 'Export-CliXml'
+    }
+
+    It 'does nothing when the cache entry already exists and hashes match' {
+        InModuleScope -ModuleName 'PSKoans' {
+            $Script:KoanResultCache = @{
+                'AboutAssertions.Koans' = @{
+                    Hash = 'abcdef'
+                }
+            }
+
+            Add-KoanCachedResult -Path 'AboutAssertions.Koans.ps1' -Result 'Result'
+        }
+
+        Should -Invoke 'Get-FileHash'
+        Should -Invoke 'Export-CliXml' -Times 0
+    }
+}

Tests/Functions/Private/Get-KoanCachedResult.Tests.ps1

@@ -0,0 +1,45 @@
+#Requires -Modules PSKoans
+
+Describe 'Get-KoanCachedResult' {
+    BeforeAll {
+        Mock 'Get-FileHash' {
+            [PSCustomObject]@{
+                Hash   = 'abcdef'
+            }
+        }
+    }
+
+    It 'gets an entry when hashes match' {
+        InModuleScope -ModuleName 'PSKoans' {
+            $Script:KoanResultCache = @{
+                'AboutAssertions.Koans' = @{
+                    Hash   = 'abcdef'
+                    Result = 'Result'
+                }
+            }
+
+            Get-KoanCachedResult -Path 'AboutAssertions.Koans.ps1'
+        } | Should -Be 'Result'
+    }
+
+    It 'returns nothing when hashes do not match' {
+        InModuleScope -ModuleName 'PSKoans' {
+            $Script:KoanResultCache = @{
+                'AboutAssertions.Koans' = @{
+                    Hash   = 'defabc'
+                    Result = 'Result'
+                }
+            }
+
+            Get-KoanCachedResult -Path 'AboutAssertions.Koans.ps1'
+        } | Should -BeNullOrEmpty
+    }
+
+    It 'returns nothing when the item is not in the cache' {
+        InModuleScope -ModuleName 'PSKoans' {
+            $Script:KoanResultCache = @{}
+
+            Get-KoanCachedResult -Path 'AboutAssertions.Koans.ps1'
+        } | Should -BeNullOrEmpty
+    }
+}

Tests/Functions/Private/Invoke-Koan.Tests.ps1

@@ -3,6 +3,9 @@
 Describe 'Invoke-Koan' {
 
     BeforeAll {
+        Mock Add-KoanCachedResult
+        Mock Get-KoanCachedResult
+
         $testFile = @{ Script = "$PSScriptRoot/ControlTests/Invoke-Koan.Control_Tests.ps1" }
     }
 
@@ -43,4 +46,34 @@ Describe 'Invoke-Koan' {
             ForEach-Object -MemberName GetType |
             Should -Be @([Exception], [NotImplementedException])
     }
+
+    Context 'item exists in cache' {
+        BeforeAll {
+            Mock Get-KoanCachedResult {
+                'CachedResult'
+            }
+        }
+
+        It 'returns a cached results if a cache entry exists' {
+            InModuleScope 'PSKoans' -Parameters $testFile {
+                param($Script)
+                Invoke-Koan @{ Script = $Script; PassThru = $true }
+            } | Should -Be 'CachedResult'
+
+            Should -Invoke 'Get-KoanCachedResult'
+            Should -Invoke 'Add-KoanCachedResult' -Times 0
+        }
+    }
+
+    Context 'item does not exist in cache' {
+        It 'adds an item to the cache when the pester run is successful' {
+            InModuleScope 'PSKoans' -Parameters $testFile {
+                param($Script)
+                Invoke-Koan @{ Script = $Script; PassThru = $true }
+            }
+
+            Should -Invoke 'Get-KoanCachedResult'
+            Should -Invoke 'Add-KoanCachedResult'
+        }
+    }
 }