Add Collection-as-Boolean

Author: nightroman

.github/workflows/test7.yml .github/workflows/test-core.yml.github/workflows/test7.yml renamed to .github/workflows/test-core.yml

@@ -1,18 +1,18 @@
-name: test7
-
-on:
-  workflow_dispatch:
-  push:
-    branches:
-      - main
-
-jobs:
-  test7:
-    runs-on: windows-latest
-    steps:
-      - uses: actions/checkout@v4
-      - name: test
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-        shell: pwsh
-        run: ./1.build.ps1 test
+name: test-core
+
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - main
+
+jobs:
+  test-core:
+    runs-on: windows-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: test-core
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        shell: pwsh
+        run: ./1.build.ps1 test

.github/workflows/test5.yml .github/workflows/test-desktop.yml.github/workflows/test5.yml renamed to .github/workflows/test-desktop.yml

@@ -1,18 +1,18 @@
-name: test5
-
-on:
-  workflow_dispatch:
-  push:
-    branches:
-      - main
-
-jobs:
-  test5:
-    runs-on: windows-latest
-    steps:
-      - uses: actions/checkout@v4
-      - name: test
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-        shell: powershell
-        run: ./1.build.ps1 test
+name: test-desktop
+
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - main
+
+jobs:
+  test-desktop:
+    runs-on: windows-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: test-desktop
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        shell: powershell
+        run: ./1.build.ps1 test

1.build.ps1

@@ -11,10 +11,9 @@ Set-StrictMode -Version Latest
 $Major = $PSVersionTable.PSVersion.Major
 
 # bootstrap
-if ($MyInvocation.ScriptName -notlike '*Invoke-Build.ps1') {
-	$InvokeBuildVersion = '5.11.0'
+if (!$MyInvocation.ScriptName.EndsWith('Invoke-Build.ps1')) {
 	$ErrorActionPreference = 1
-	$PSScriptRoot = Split-Path $MyInvocation.MyCommand.Definition
+	$InvokeBuildVersion = '5.14.14'
 	$ib = "$PSScriptRoot/packages/InvokeBuild/$InvokeBuildVersion/Invoke-Build.ps1"
 
 	if (!(Test-Path -LiteralPath $ib)) {

Basic/Collection-as-Boolean/.test.ps1

@@ -0,0 +1,16 @@
+
+task Test-1-expected {
+	$1, $2, $3, $4 = & ./Test-1-expected.ps1
+	equals $1 $true
+	equals $2 $true
+	equals $3 $true
+	equals $4 $true
+}
+
+task Test-2-may-be-unexpected {
+	$1, $2, $3, $4 = & ./Test-2-may-be-unexpected.ps1
+	equals $1 $false
+	equals $2 $false
+	equals $3 $false
+	equals $4 $false
+}

Basic/Collection-as-Boolean/README.md

@@ -0,0 +1,14 @@
+# Collection as Boolean
+
+When a collection type (.NET array, generic list, `ArrayList`, etc.) is used
+in a Boolean context, in many cases PowerShell evaluates it as `$true` if it
+contains at least one item, and `$false` if it is empty.
+
+This is not true and may be unexpected if a collection has a single item which
+is evaluated as `$false` in a Boolean context. Such not empty collections are
+evaluated as `$false`.
+
+Scripts
+
+- [Test-1-expected.ps1](Test-1-expected.ps1) shows expected results
+- [Test-2-may-be-unexpected.ps1](Test-2-may-be-unexpected.ps1) shows potentially unexpected results

Basic/Collection-as-Boolean/Test-1-expected.ps1

@@ -0,0 +1,14 @@
+
+### These not empty arrays are evaluated as $true
+
+# number
+@(42) -as [bool]
+
+# string
+@('abc') -as [bool]
+
+# object
+@($Host) -as [bool]
+
+# Boolean
+@($true) -as [bool]

Basic/Collection-as-Boolean/Test-2-may-be-unexpected.ps1

@@ -0,0 +1,14 @@
+
+### These not empty arrays are evaluated as $false
+
+# number
+@(0) -as [bool]
+
+# string
+@('') -as [bool]
+
+# object
+@($null) -as [bool]
+
+# Boolean
+@($false) -as [bool]

README.md

@@ -26,6 +26,7 @@ to their directory. See also [TESTS]. Some scripts require
 - [Automatic variables as parameters or local variables](Basic/Automatic-variables)
 - [Break and Continue with not matching label](Basic/Break-and-Continue-with-not-matching-label)
 - [Break and Continue without loop](Basic/Break-and-Continue-without-loop)
+- [Collection as Boolean](Basic/Collection-as-Boolean)
 - [Collection property enumeration](Basic/Collection-property-enumeration)
 - [Comparison operators work differently with scalars and collections](Basic/Comparison-operators-with-collections)
 - [Compound assignment operators](Basic/Compound-assignment-operators)