better install path (#41)

* Test-PathWritable

* update logic

Author: iricigor

Private/Get-InstallPath.ps1

@@ -1,7 +1,8 @@
 function Get-InstallPath {
 
     # returns OS specific path for module installation, it support only -Scope CurrentUser
-    if ($IsLinux -or $IsOSX) {
+    
+    $defaultPath = if ($IsLinux -or $IsOSX) {
         #"$HOME/.local/share/powershell/Modules"
         # https://github.com/PowerShell/PowerShellGet/blob/d4dfebbbec4dfbe73392719a8a331541ed75d508/src/PowerShellGet/private/modulefile/PartOne.ps1#L71
         Join-Path (Split-Path -Path ([System.Management.Automation.Platform]::SelectProductNameForDirectory('USER_MODULES')) -Parent) 'Modules'
@@ -18,4 +19,22 @@ function Get-InstallPath {
         }
     }
 
+    $ModulePaths = $Env:PSModulePath -split (';:'[[int]($IsLinux -or $IsMacOS)])
+    if ($defaultPath -in $ModulePaths) {
+        $defaultPath
+    } else {
+        # default path is not in findable by get-module, try to avoid it
+        $writablePath = ''
+        foreach ($P1 in $ModulePaths) {
+            if (([string]::IsNullOrEmpty($writablePath)) -and (Test-PathWritable $P1)) {
+                $writablePath = $P1
+            }
+        }
+        if ([string]::IsNullOrEmpty($writablePath)) {
+            # we found no writable paths, return default one
+            $defaultPath
+        } else {
+            $writablePath
+        }
+    }
 }

Private/Test-PathWritable.ps1

@@ -0,0 +1,21 @@
+function Test-PathWritable {
+    param (
+        [string]$Path
+    )
+    # returns true if given directory is writable, false otherwise
+    if (!(Test-Path $Path -PathType Container)) {
+        #throw "Path $Path is not a directory"
+        $false
+    }
+
+    $FileName = Join-Path $Path ([io.path]::GetRandomFileName())
+
+    try {
+        [io.file]::OpenWrite($FileName).close()
+        [io.file]::Delete($FileName)
+        $true
+    } catch {
+        $false
+    }
+    
+}

Tests/module/InstallModuleFromGit.Tests.ps1

@@ -11,7 +11,7 @@
 $ModuleName = 'InstallModuleFromGit'
 $here = Split-Path -Parent $MyInvocation.MyCommand.Path     # Tests/Module folder
 $root = (get-item $here).Parent.Parent.FullName             # module root folder
-Import-Module (Join-Path $root "$ModuleName.psm1") -Force
+Import-Module (Join-Path $root "$ModuleName.psd1") -Force
 
 
 #
@@ -67,6 +67,8 @@ Describe 'Proper Functions Declaration' -Tag 'Other' {
 
 Describe 'Proper Documentation' -Tag 'Documentation' {
 
+    Push-Location $root
+
 	It 'Updates documentation and does git diff' {
 
         # install PlatyPS
@@ -92,6 +94,7 @@ Describe 'Proper Documentation' -Tag 'Documentation' {
         }
     }
 
+    Pop-Location
 }