Add foreach Assignment to AvoidAssignmentToAutomaticVariable (#2021)

* Add Evaluation for foreach Assignment

* Add Tests for foreach Assignment

* Update Tests for Consistency

* Remove Unnecessary ExcludeRule

* Update Test Description

---------

Co-authored-by: PoshAJ <[email protected]>

Author: poshAJ

Rules/AvoidAssignmentToAutomaticVariable.cs

@@ -79,6 +79,31 @@ public IEnumerable<DiagnosticRecord> AnalyzeScript(Ast ast, string fileName)
                 }
             }
 
+            IEnumerable<Ast> forEachStatementAsts = ast.FindAll(testAst => testAst is ForEachStatementAst, searchNestedScriptBlocks: true);
+            foreach (ForEachStatementAst forEachStatementAst in forEachStatementAsts)
+            {
+                var variableExpressionAst = forEachStatementAst.Variable;
+                var variableName = variableExpressionAst.VariablePath.UserPath;
+                if (_readOnlyAutomaticVariables.Contains(variableName, StringComparer.OrdinalIgnoreCase))
+                {
+                    yield return new DiagnosticRecord(DiagnosticRecordHelper.FormatError(Strings.AvoidAssignmentToReadOnlyAutomaticVariableError, variableName),
+                                                      variableExpressionAst.Extent, GetName(), DiagnosticSeverity.Error, fileName, variableName);
+                }
+
+                if (_readOnlyAutomaticVariablesIntroducedInVersion6_0.Contains(variableName, StringComparer.OrdinalIgnoreCase))
+                {
+                    var severity = IsPowerShellVersion6OrGreater() ? DiagnosticSeverity.Error : DiagnosticSeverity.Warning;
+                    yield return new DiagnosticRecord(DiagnosticRecordHelper.FormatError(Strings.AvoidAssignmentToReadOnlyAutomaticVariableIntroducedInPowerShell6_0Error, variableName),
+                                                      variableExpressionAst.Extent, GetName(), severity, fileName, variableName);
+                }
+
+                if (_writableAutomaticVariables.Contains(variableName, StringComparer.OrdinalIgnoreCase))
+                {
+                    yield return new DiagnosticRecord(DiagnosticRecordHelper.FormatError(Strings.AvoidAssignmentToWritableAutomaticVariableError, variableName),
+                                                      variableExpressionAst.Extent, GetName(), DiagnosticSeverity.Warning, fileName, variableName);
+                }
+            }
+
             IEnumerable<Ast> parameterAsts = ast.FindAll(testAst => testAst is ParameterAst, searchNestedScriptBlocks: true);
             foreach (ParameterAst parameterAst in parameterAsts)
             {

Tests/Rules/AvoidAssignmentToAutomaticVariable.tests.ps1

@@ -65,13 +65,22 @@ Describe "AvoidAssignmentToAutomaticVariables" {
         It "Variable <VariableName> produces warning of Severity <ExpectedSeverity>" -TestCases $testCases_AutomaticVariables {
             param ($VariableName, $ExpectedSeverity)
 
-            $warnings = Invoke-ScriptAnalyzer -ScriptDefinition "`$${VariableName} = 'foo'" -ExcludeRule PSUseDeclaredVarsMoreThanAssignments
+            [System.Array] $warnings = Invoke-ScriptAnalyzer -ScriptDefinition "`$${VariableName} = 'foo'" -ExcludeRule PSUseDeclaredVarsMoreThanAssignments
             $warnings.Count | Should -Be 1
             $warnings.Severity | Should -Be $ExpectedSeverity
             $warnings.RuleName | Should -Be $ruleName
         }
 
-        It "Using Variable <VariableName> as parameter name produces warning of Severity error" -TestCases $testCases_AutomaticVariables {
+        It "Using Variable <VariableName> as foreach assignment produces warning of Severity <ExpectedSeverity>" -TestCases $testCases_AutomaticVariables {
+            param ($VariableName, $ExpectedSeverity)
+
+            [System.Array] $warnings = Invoke-ScriptAnalyzer -ScriptDefinition "foreach (`$$VariableName in `$foo) {}"
+            $warnings.Count | Should -Be 1
+            $warnings.Severity | Should -Be $ExpectedSeverity
+            $warnings.RuleName | Should -Be $ruleName
+        }
+
+        It "Using Variable <VariableName> as parameter name produces warning of Severity <ExpectedSeverity>" -TestCases $testCases_AutomaticVariables {
             param ($VariableName, $ExpectedSeverity)
 
             [System.Array] $warnings = Invoke-ScriptAnalyzer -ScriptDefinition "function foo{Param(`$$VariableName)}" -ExcludeRule PSReviewUnusedParameter
@@ -80,7 +89,7 @@ Describe "AvoidAssignmentToAutomaticVariables" {
             $warnings.RuleName | Should -Be $ruleName
         }
 
-        It "Using Variable <VariableName> as parameter name in param block produces warning of Severity error" -TestCases $testCases_AutomaticVariables {
+        It "Using Variable <VariableName> as parameter name in param block produces warning of Severity <ExpectedSeverity>" -TestCases $testCases_AutomaticVariables {
             param ($VariableName, $ExpectedSeverity)
 
             [System.Array] $warnings = Invoke-ScriptAnalyzer -ScriptDefinition "function foo(`$$VariableName){}"