Tighten DSC resource detection in AvoidAlias

Rules/AvoidAlias.cs

@@ -195,7 +195,25 @@ private bool IgnoreCommandast(CommandAst cmdAst)
 
         private bool IsDscResourceDeclaration(CommandAst cmdAst)
         {
-            if (GetDscResourceBody(cmdAst) == null)
+            bool hasConfigurationAncestor = false;
+            for (Ast parent = cmdAst.Parent; parent != null; parent = parent.Parent)
+            {
+                if (parent is ConfigurationDefinitionAst)
+                {
+                    hasConfigurationAncestor = true;
+                    break;
+                }
+
+                if (parent is FunctionDefinitionAst
+                    || parent is HashtableAst
+                    || parent is AssignmentStatementAst
+                    || parent is ParenExpressionAst)
+                {
+                    return false;
+                }
+            }
+
+            if (!hasConfigurationAncestor || GetDscResourceBody(cmdAst) == null)
             {
                 return false;
             }
@@ -207,7 +225,17 @@ private bool IsDscResourceDeclaration(CommandAst cmdAst)
                     return true;
                 }
 
-                if (parent is FunctionDefinitionAst || parent is HashtableAst)
+                if (parent is FunctionDefinitionAst
+                    || parent is HashtableAst
+                    || parent is AssignmentStatementAst
+                    || parent is ParenExpressionAst)
+                {
+                    return false;
+                }
+
+                if (parent is CommandExpressionAst commandExpression
+                    && (!(commandExpression.Expression is ScriptBlockExpressionAst body)
+                        || !IsFollowingLineDscResourceBody(body)))
                 {
                     return false;
                 }
@@ -236,6 +264,41 @@ private bool IsDscResourceDeclaration(CommandAst cmdAst)
             return false;
         }
 
+        private bool IsFollowingLineDscResourceBody(ScriptBlockExpressionAst body)
+        {
+            if (!(body.Parent is CommandExpressionAst bodyExpression)
+                || !(bodyExpression.Parent is PipelineAst bodyPipeline)
+                || bodyPipeline.PipelineElements.Count != 1
+                || bodyPipeline.PipelineElements[0] != bodyExpression)
+            {
+                return false;
+            }
+
+            Ast statement = bodyPipeline;
+            for (Ast parent = bodyPipeline.Parent; parent != null; parent = parent.Parent)
+            {
+                var statements = (parent as NamedBlockAst)?.Statements
+                    ?? (parent as StatementBlockAst)?.Statements;
+                if (statements == null)
+                {
+                    statement = parent;
+                    continue;
+                }
+
+                int index = statements.IndexOf(statement as StatementAst);
+                if (index <= 0 || !(statements[index - 1] is PipelineAst declarationPipeline)
+                    || declarationPipeline.PipelineElements.Count != 1
+                    || !(declarationPipeline.PipelineElements[0] is CommandAst declaration))
+                {
+                    return false;
+                }
+
+                return GetDscResourceBody(declaration) == body;
+            }
+
+            return false;
+        }
+
         private ScriptBlockExpressionAst GetDscResourceBody(CommandAst cmdAst)
         {
             if (cmdAst.InvocationOperator != TokenKind.Unknown
@@ -246,6 +309,13 @@ private ScriptBlockExpressionAst GetDscResourceBody(CommandAst cmdAst)
                 return null;
             }
 
+            if (!(cmdAst.Parent is PipelineAst commandPipeline)
+                || commandPipeline.PipelineElements.Count != 1
+                || commandPipeline.PipelineElements[0] != cmdAst)
+            {
+                return null;
+            }
+
             if (cmdAst.CommandElements.Count == 3)
             {
                 return cmdAst.CommandElements[2] as ScriptBlockExpressionAst;

Tests/Rules/AvoidUsingAlias.tests.ps1

@@ -146,6 +146,45 @@ Configuration PackageTest {
             $violations[5].Extent.Text | Should -Be 'Verb'
             $violations[6].Extent.Text | Should -Be 'Verb'
         }
+
+        It "does not ignore executable commands in assignment and expression contexts or pipelines" {
+            $target = @'
+{
+    $items = ChildItem . {}
+    $result = Verb Argument {}
+    $action = { Verb Argument {} }
+    Name = (Verb Argument {})
+    Script ScriptExample {
+        SetScript =
+        {
+            Verb Argument {}
+        }
+    }
+    Verb Argument {} | Out-Null
+    gci . | Out-Null
+    {
+    }
+}
+'@
+            $ast = [System.Management.Automation.Language.Parser]::ParseInput($target, [ref]$null, [ref]$null)
+            $body = $ast.EndBlock.Statements[0].PipelineElements[0].Expression.Copy()
+            $configuration = [System.Management.Automation.Language.ConfigurationDefinitionAst]::new(
+                $ast.Extent, $body, 'Resource',
+                [System.Management.Automation.Language.StringConstantExpressionAst]::new($ast.Extent, 'Test', 'BareWord'))
+            $rule = [Microsoft.Windows.PowerShell.ScriptAnalyzer.BuiltinRules.AvoidAlias]::new()
+
+            $violations = @($rule.AnalyzeScript($configuration, $null))
+
+            $violations.Count | Should -Be 7
+            $violations[0].Extent.Text | Should -Be 'ChildItem'
+            $violations[0].SuggestedCorrections[0].Text | Should -Be 'Get-ChildItem'
+            $violations[1].Extent.Text | Should -Be 'Verb'
+            $violations[2].Extent.Text | Should -Be 'Verb'
+            $violations[3].Extent.Text | Should -Be 'Verb'
+            $violations[4].Extent.Text | Should -Be 'Verb'
+            $violations[5].Extent.Text | Should -Be 'Verb'
+            $violations[6].Extent.Text | Should -Be 'gci'
+        }
     }
 
     Context "Settings file provides allowlist" {