Add check for builtin variables for GlobalVar rule

Author: yutingc

Engine/Helper.cs

@@ -494,6 +494,23 @@ public bool IsVariableGlobalOrEnvironment(VariableExpressionAst varAst, Ast ast)
             return VariableAnalysisDictionary[ast].IsGlobalOrEnvironment(varAst);
         }
 
+
+        /// <summary>
+        /// Checks whether a variable is a built-in variable.
+        /// </summary>
+        /// <param name="ast"></param>
+        /// <returns></returns>
+        public bool IsVariableGlobal(VariableExpressionAst varAst)
+        {
+            if (varAst.VariablePath.IsGlobal)
+            {
+                string varName = varAst.VariablePath.UserPath.Remove(varAst.VariablePath.UserPath.IndexOf("global:", StringComparison.OrdinalIgnoreCase), "global:".Length);
+                return !SpecialVars.InitializedVariables.Contains(varName, StringComparer.OrdinalIgnoreCase);
+            }
+            return false;
+        }
+
+
         /// <summary>
         /// Checks whether all the code path of ast returns.
         /// Runs InitializeVariableAnalysis before calling this method

Rules/AvoidGlobalVars.cs

@@ -41,7 +41,7 @@ public IEnumerable<DiagnosticRecord> AnalyzeScript(Ast ast, string fileName)
             {
                 foreach (VariableExpressionAst varAst in varAsts)
                 {
-                    if (varAst.VariablePath.IsGlobal)
+                    if (Helper.Instance.IsVariableGlobal(varAst))
                     {
                         yield return
                             new DiagnosticRecord(

Tests/Rules/AvoidGlobalOrUnitializedVars.ps1

@@ -1,4 +1,7 @@
-$Global:1 = "Globalization?"
+$Global:1 = "globalVar“
+$Global:DebugPreference
+
+
 
 function NotGlobal {
     $localVars = "Localization?"

Tests/Rules/AvoidGlobalOrUnitializedVarsNoViolations.ps1

@@ -1,4 +1,7 @@
-function Test {
+$Global:DebugPreference
+
+
+function Test {
     $initialized = "Initialized"
     $noglobal = "local"
     $env:ShouldNotRaiseError
@@ -31,18 +34,11 @@ $proc[0]
 
 function Test-PreferenceVariable
 {
-    Param(
-        [switch]
-        $a,
-
-        [System.Management.Automation.SwitchParameter]
-        $b
-    )
 
    if (-not $PSBoundParameters.ContainsKey('Verbose')) {
        $VerbosePreference = $PSCmdlet.GetVariableValue('VerbosePreference') -as 
         [System.Management.Automation.ActionPreference]
         }
 
         $VerbosePreference
-}
+    }