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Add more automatic variables to PSAvoidAssignmentToAutomaticVariables that are not read-only but should still not be assigned to in most cases (#1394)
* Add more automatic variables to PSAvoidAssignmentToAutomaticVariables that are not read-only but should still not be assigned to in most cases * Update Rules/AvoidAssignmentToAutomaticVariable.cs Co-Authored-By: Robert Holt <rjmholt@gmail.com> * rename variable to _writableAutomaticVariables Co-authored-by: Robert Holt <rjmholt@gmail.com>
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4 files changed

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‎Rules/AvoidAssignmentToAutomaticVariable.cs‎

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Original file line numberDiff line numberDiff line change
@@ -33,6 +33,16 @@ public class AvoidAssignmentToAutomaticVariable : IScriptRule
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"IsCoreCLR", "IsLinux", "IsMacOS", "IsWindows"
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};
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private static readonly IReadOnlyList<string> _writableAutomaticVariables = new List<string>()
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{
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// Attempting to assign to any of those could cause issues, only in some special cases could assignment be by design
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"_", "AllNodes", "Args", "ConsoleFilename", "Event", "EventArgs", "EventSubscriber", "ForEach", "Input", "Matches", "MyInvocation",
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"NestedPromptLevel", "Profile", "PSBoundParameters", "PsCmdlet", "PSCommandPath", "PSDebugContext",
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"PSItem", "PSScriptRoot", "PSSenderInfo", "Pwd", "PSCommandPath", "ReportErrorShowExceptionClass",
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"ReportErrorShowInnerException", "ReportErrorShowSource", "ReportErrorShowStackTrace", "Sender",
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"StackTrace", "This"
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};
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/// <summary>
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/// Checks for assignment to automatic variables.
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/// <param name="ast">The script's ast</param>
@@ -61,6 +71,12 @@ public IEnumerable<DiagnosticRecord> AnalyzeScript(Ast ast, string fileName)
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yield return new DiagnosticRecord(DiagnosticRecordHelper.FormatError(Strings.AvoidAssignmentToReadOnlyAutomaticVariableIntroducedInPowerShell6_0Error, variableName),
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variableExpressionAst.Extent, GetName(), severity, fileName);
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}
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if (_writableAutomaticVariables.Contains(variableName, StringComparer.OrdinalIgnoreCase))
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{
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yield return new DiagnosticRecord(DiagnosticRecordHelper.FormatError(Strings.AvoidAssignmentToWritableAutomaticVariableError, variableName),
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variableExpressionAst.Extent, GetName(), DiagnosticSeverity.Warning, fileName);
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}
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}
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IEnumerable<Ast> parameterAsts = ast.FindAll(testAst => testAst is ParameterAst, searchNestedScriptBlocks: true);
@@ -79,12 +95,19 @@ public IEnumerable<DiagnosticRecord> AnalyzeScript(Ast ast, string fileName)
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yield return new DiagnosticRecord(DiagnosticRecordHelper.FormatError(Strings.AvoidAssignmentToReadOnlyAutomaticVariableError, variableName),
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variableExpressionAst.Extent, GetName(), DiagnosticSeverity.Error, fileName);
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}
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if (_readOnlyAutomaticVariablesIntroducedInVersion6_0.Contains(variableName, StringComparer.OrdinalIgnoreCase))
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{
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var severity = IsPowerShellVersion6OrGreater() ? DiagnosticSeverity.Error : DiagnosticSeverity.Warning;
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yield return new DiagnosticRecord(DiagnosticRecordHelper.FormatError(Strings.AvoidAssignmentToReadOnlyAutomaticVariableIntroducedInPowerShell6_0Error, variableName),
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variableExpressionAst.Extent, GetName(), severity, fileName);
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}
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if (_writableAutomaticVariables.Contains(variableName, StringComparer.OrdinalIgnoreCase))
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{
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yield return new DiagnosticRecord(DiagnosticRecordHelper.FormatError(Strings.AvoidAssignmentToWritableAutomaticVariableError, variableName),
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variableExpressionAst.Extent, GetName(), DiagnosticSeverity.Warning, fileName);
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}
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}
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}
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‎Rules/Strings.Designer.cs‎

Lines changed: 9 additions & 0 deletions
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‎Rules/Strings.resx‎

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Original file line numberDiff line numberDiff line change
@@ -1104,6 +1104,9 @@
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<data name="UseProcessBlockForPipelineCommandName" xml:space="preserve">
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<value>UseProcessBlockForPipelineCommand</value>
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</data>
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<data name="AvoidAssignmentToWritableAutomaticVariableError" xml:space="preserve">
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<value>The Variable '{0}' is an automatic variable that is built into PowerShell, assigning to it might have undesired side effects. If assignment is not by design, please use a different name.</value>
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</data>
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<data name="UseConsistentWhitespaceErrorSpaceBetweenParameter" xml:space="preserve">
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<value>Use only 1 whitespace between parameter names or values.</value>
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</data>

‎Tests/Rules/AvoidAssignmentToAutomaticVariable.tests.ps1‎

Lines changed: 46 additions & 21 deletions
Original file line numberDiff line numberDiff line change
@@ -9,29 +9,54 @@ Describe "AvoidAssignmentToAutomaticVariables" {
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$excpectedSeverityForAutomaticVariablesInPowerShell6 = 'Error'
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}
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$testCases_ReadOnlyVariables = @(
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@{ VariableName = '?'; ExpectedSeverity = 'Error'; }
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@{ VariableName = 'Error' ; ExpectedSeverity = 'Error' }
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@{ VariableName = 'ExecutionContext'; ExpectedSeverity = 'Error' }
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@{ VariableName = 'false'; ExpectedSeverity = 'Error' }
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@{ VariableName = 'Home'; ExpectedSeverity = 'Error' }
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@{ VariableName = 'Host'; ExpectedSeverity = 'Error' }
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@{ VariableName = 'PID'; ExpectedSeverity = 'Error' }
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@{ VariableName = 'PSCulture'; ExpectedSeverity = 'Error' }
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@{ VariableName = 'PSEdition'; ExpectedSeverity = 'Error' }
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@{ VariableName = 'PSHome'; ExpectedSeverity = 'Error' }
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@{ VariableName = 'PSUICulture'; ExpectedSeverity = 'Error' }
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@{ VariableName = 'PSVersionTable'; ExpectedSeverity = 'Error' }
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@{ VariableName = 'ShellId'; ExpectedSeverity = 'Error' }
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@{ VariableName = 'true'; ExpectedSeverity = 'Error' }
27-
# Variables introuced only in PowerShell 6.0 have a Severity of Warning only
12+
$testCases_AutomaticVariables = @(
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@{ VariableName = '?'; ExpectedSeverity = 'Error'; IsReadOnly = $true }
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@{ VariableName = 'Error' ; ExpectedSeverity = 'Error'; IsReadOnly = $true }
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@{ VariableName = 'ExecutionContext'; ExpectedSeverity = 'Error'; IsReadOnly = $true }
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@{ VariableName = 'false'; ExpectedSeverity = 'Error'; IsReadOnly = $true }
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@{ VariableName = 'Home'; ExpectedSeverity = 'Error'; IsReadOnly = $true }
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@{ VariableName = 'Host'; ExpectedSeverity = 'Error'; IsReadOnly = $true }
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@{ VariableName = 'PID'; ExpectedSeverity = 'Error'; IsReadOnly = $true }
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@{ VariableName = 'PSCulture'; ExpectedSeverity = 'Error'; IsReadOnly = $true }
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@{ VariableName = 'PSEdition'; ExpectedSeverity = 'Error'; IsReadOnly = $true }
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@{ VariableName = 'PSHome'; ExpectedSeverity = 'Error'; IsReadOnly = $true }
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@{ VariableName = 'PSUICulture'; ExpectedSeverity = 'Error'; IsReadOnly = $true }
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@{ VariableName = 'PSVersionTable'; ExpectedSeverity = 'Error'; IsReadOnly = $true }
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@{ VariableName = 'ShellId'; ExpectedSeverity = 'Error'; IsReadOnly = $true }
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@{ VariableName = 'true'; ExpectedSeverity = 'Error'; IsReadOnly = $true }
27+
# Variables introduced only in PowerShell 6+ have a Severity of Warning only
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@{ VariableName = 'IsCoreCLR'; ExpectedSeverity = $excpectedSeverityForAutomaticVariablesInPowerShell6; OnlyPresentInCoreClr = $true }
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@{ VariableName = 'IsLinux'; ExpectedSeverity = $excpectedSeverityForAutomaticVariablesInPowerShell6; OnlyPresentInCoreClr = $true }
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@{ VariableName = 'IsMacOS'; ExpectedSeverity = $excpectedSeverityForAutomaticVariablesInPowerShell6; OnlyPresentInCoreClr = $true }
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@{ VariableName = 'IsWindows'; ExpectedSeverity = $excpectedSeverityForAutomaticVariablesInPowerShell6; OnlyPresentInCoreClr = $true }
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@{ VariableName = '_'; ExpectedSeverity = 'Warning' }
33+
@{ VariableName = 'AllNodes'; ExpectedSeverity = 'Warning' }
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@{ VariableName = 'Args'; ExpectedSeverity = 'Warning' }
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@{ VariableName = 'ConsoleFilename'; ExpectedSeverity = 'Warning' }
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@{ VariableName = 'Event'; ExpectedSeverity = 'Warning' }
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@{ VariableName = 'EventArgs'; ExpectedSeverity = 'Warning' }
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@{ VariableName = 'EventSubscriber'; ExpectedSeverity = 'Warning' }
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@{ VariableName = 'ForEach'; ExpectedSeverity = 'Warning' }
40+
@{ VariableName = 'Input'; ExpectedSeverity = 'Warning' }
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@{ VariableName = 'Matches'; ExpectedSeverity = 'Warning' }
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@{ VariableName = 'MyInvocation'; ExpectedSeverity = 'Warning' }
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@{ VariableName = 'NestedPromptLevel'; ExpectedSeverity = 'Warning' }
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@{ VariableName = 'Profile'; ExpectedSeverity = 'Warning' }
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@{ VariableName = 'PSBoundParameters'; ExpectedSeverity = 'Warning' }
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@{ VariableName = 'PsCmdlet'; ExpectedSeverity = 'Warning' }
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@{ VariableName = 'PSCommandPath'; ExpectedSeverity = 'Warning' }
48+
@{ VariableName = 'ReportErrorShowExceptionClass'; ExpectedSeverity = 'Warning' }
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@{ VariableName = 'ReportErrorShowInnerException'; ExpectedSeverity = 'Warning' }
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@{ VariableName = 'ReportErrorShowSource'; ExpectedSeverity = 'Warning' }
51+
@{ VariableName = 'ReportErrorShowStackTrace'; ExpectedSeverity = 'Warning' }
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@{ VariableName = 'Sender'; ExpectedSeverity = 'Warning' }
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@{ VariableName = 'StackTrace'; ExpectedSeverity = 'Warning' }
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@{ VariableName = 'This'; ExpectedSeverity = 'Warning' }
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)
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34-
It "Variable <VariableName> produces warning of Severity <ExpectedSeverity>" -TestCases $testCases_ReadOnlyVariables {
57+
$testCases_ReadOnlyAutomaticVariables = $testCases_AutomaticVariables | Where-Object { $_.IsReadonly }
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59+
It "Variable <VariableName> produces warning of Severity <ExpectedSeverity>" -TestCases $testCases_AutomaticVariables {
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param ($VariableName, $ExpectedSeverity)
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$warnings = Invoke-ScriptAnalyzer -ScriptDefinition "`$${VariableName} = 'foo'" -ExcludeRule PSUseDeclaredVarsMoreThanAssignments
@@ -40,7 +65,7 @@ Describe "AvoidAssignmentToAutomaticVariables" {
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$warnings.RuleName | Should -Be $ruleName
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}
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43-
It "Using Variable <VariableName> as parameter name produces warning of Severity error" -TestCases $testCases_ReadOnlyVariables {
68+
It "Using Variable <VariableName> as parameter name produces warning of Severity error" -TestCases $testCases_AutomaticVariables {
4469
param ($VariableName, $ExpectedSeverity)
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4671
[System.Array] $warnings = Invoke-ScriptAnalyzer -ScriptDefinition "function foo{Param(`$$VariableName)}" -ExcludeRule PSReviewUnusedParameter
@@ -49,7 +74,7 @@ Describe "AvoidAssignmentToAutomaticVariables" {
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$warnings.RuleName | Should -Be $ruleName
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}
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52-
It "Using Variable <VariableName> as parameter name in param block produces warning of Severity error" -TestCases $testCases_ReadOnlyVariables {
77+
It "Using Variable <VariableName> as parameter name in param block produces warning of Severity error" -TestCases $testCases_AutomaticVariables {
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param ($VariableName, $ExpectedSeverity)
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5580
[System.Array] $warnings = Invoke-ScriptAnalyzer -ScriptDefinition "function foo(`$$VariableName){}"
@@ -77,8 +102,8 @@ Describe "AvoidAssignmentToAutomaticVariables" {
77102
$warnings.Count | Should -Be 0
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}
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80-
It "Setting Variable <VariableName> throws exception in applicable PowerShell version to verify the variables is read-only" -TestCases $testCases_ReadOnlyVariables {
81-
param ($VariableName, $ExpectedSeverity, $OnlyPresentInCoreClr)
105+
It "Setting Variable <VariableName> throws exception in applicable PowerShell version to verify the variables is read-only" -TestCases $testCases_ReadOnlyAutomaticVariables {
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param ($VariableName, $ExpectedSeverity, $OnlyPresentInCoreClr, [bool] $IsReadOnly)
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83108
if ($OnlyPresentInCoreClr -and !$IsCoreCLR)
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{

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