Expansion context

Package.swift

@@ -53,7 +53,13 @@ let package = Package(
         ),
         .testTarget(
             name: "PrincipleMacrosTests",
-            dependencies: ["PrincipleMacros"]
+            dependencies: [
+                "PrincipleMacros",
+                .product(
+                    name: "SwiftSyntaxMacroExpansion",
+                    package: "swift-syntax"
+                )
+            ]
         )
     ]
 )

Sources/PrincipleMacros/ExpansionContext/MacroExpansionContext.swift

@@ -0,0 +1,21 @@
+//
+//  MacroExpansionContext.swift
+//  PrincipleMacros
+//
+//  Created by Kamil Strzelecki on 30/03/2025.
+//  Copyright © 2025 Kamil Strzelecki. All rights reserved.
+//
+
+import SwiftSyntaxMacros
+
+extension MacroExpansionContext {
+
+    public func diagnose(
+        node: some SyntaxProtocol,
+        errorMessage: String
+    ) {
+        let message = MacroExpansionErrorMessage(errorMessage)
+        let diagnostic = Diagnostic(node: node, message: message)
+        diagnose(diagnostic)
+    }
+}

Sources/PrincipleMacros/Parsers/Common/Parser.swift

@@ -7,18 +7,19 @@
 //
 
 import SwiftSyntax
+import SwiftSyntaxMacros
 
 public protocol Parser {
 
     associatedtype ResultsCollection: ParserResultsCollection
 
     static func parse(
         declaration: DeclSyntaxProtocol,
-        in context: DiagnosticContext
+        in context: MacroExpansionContext
     ) -> ResultsCollection
 
     static func parse(
         memberBlock: MemberBlockSyntax,
-        in context: DiagnosticContext
+        in context: MacroExpansionContext
     ) -> ResultsCollection
 }

Sources/PrincipleMacros/Parsers/Common/_Parser.swift

@@ -6,14 +6,17 @@
 //  Copyright © 2025 Kamil Strzelecki. All rights reserved.
 //
 
+import SwiftSyntax
+import SwiftSyntaxMacros
+
 internal protocol _Parser: Parser
 where ResultsCollection: _ParserResultsCollection {}
 
 extension _Parser {
 
     public static func parse(
         memberBlock: MemberBlockSyntax,
-        in context: DiagnosticContext
+        in context: MacroExpansionContext
     ) -> ResultsCollection {
         ResultsCollection(
             memberBlock.members.flatMap { member in

Sources/PrincipleMacros/Parsers/EnumCases/EnumCasesParser.swift

@@ -7,12 +7,13 @@
 //
 
 import SwiftSyntax
+import SwiftSyntaxMacros
 
 public enum EnumCasesParser: _Parser {
 
     public static func parse(
         declaration: DeclSyntaxProtocol,
-        in _: DiagnosticContext
+        in _: MacroExpansionContext
     ) -> EnumCasesList {
         guard let declaration = EnumCaseDeclSyntax(declaration) else {
             return .init()

Sources/PrincipleMacros/Parsers/Properties/PropertiesParser.swift

@@ -7,12 +7,13 @@
 //
 
 import SwiftSyntax
+import SwiftSyntaxMacros
 
 public enum PropertiesParser: _Parser {
 
     public static func parse(
         declaration: DeclSyntaxProtocol,
-        in context: DiagnosticContext
+        in context: MacroExpansionContext
     ) -> PropertiesList {
         guard let declaration = VariableDeclSyntax(declaration) else {
             return .init()

Tests/PrincipleMacrosTests/Parsers/EnumCasesParserTests.swift

@@ -7,11 +7,12 @@
 //
 
 @testable import PrincipleMacros
+import SwiftSyntaxMacroExpansion
 import Testing
 
 internal struct EnumCasesParserTests {
 
-    private let context = DiagnosticContextMock()
+    private let context = BasicMacroExpansionContext()
 
     @Test
     func testEnumCase() throws {

Tests/PrincipleMacrosTests/Parsers/PropertiesParserTests.swift

@@ -7,11 +7,12 @@
 //
 
 @testable import PrincipleMacros
+import SwiftSyntaxMacroExpansion
 import Testing
 
 internal struct PropertiesParserTests {
 
-    private let context = DiagnosticContextMock()
+    private let context = BasicMacroExpansionContext()
 
     @Test
     func testStoredLet() throws {