add init

Sources/SGFKit/Node.swift

@@ -124,6 +124,20 @@ public struct Property: Hashable, Equatable, Sendable {
         self.identifier = identifier
         self.values = values
     }
+
+    /// Creates a Property with type-safe property definition and value.
+    /// - Parameters:
+    ///   - definition: A property definition that specifies the property type.
+    ///   - value: The value conforming to the property definition's value type.
+    public init<Game: SGFKit.Game, Value: PropertyValue>(
+        _ definition: PropertyDefinition<Game, Value>,
+        value: Value
+    ) {
+        self.init(
+            identifier: definition.name,
+            values: value.convertToComposes()
+        )
+    }
 }
 
 /// An enum indicating a composed value of a node.

Tests/SGFKitTests/PropertyTests.swift

@@ -0,0 +1,50 @@
+@testable import SGFKit
+import Testing
+
+@Suite
+struct PropertyTests {
+
+    @Test
+    func propertyInitializerWithMove() throws {
+        let point = GoPoint(column: 3, row: 3)
+        let definition: PropertyDefinition<Go, GoPoint> = .black
+        let property = Property(definition, value: point)
+
+        #expect(property.identifier == "B")
+        #expect(property.values == [.single("cc")])
+    }
+
+    @Test
+    func propertyInitializerWithText() throws {
+        let comment = "This is a test comment"
+        let definition: PropertyDefinition<Go, String> = .comment
+        let property = Property(definition, value: comment)
+
+        #expect(property.identifier == "C")
+        #expect(property.values == [.single(comment)])
+    }
+
+    @Test
+    func propertyInitializerWithNumber() throws {
+        let fileFormat = 4
+        let definition: PropertyDefinition<Go, Int> = .fileFormat
+        let property = Property(definition, value: fileFormat)
+
+        #expect(property.identifier == "FF")
+        #expect(property.values == [.single("4")])
+    }
+
+    @Test
+    func propertyInitializerWithList() throws {
+        let go = try Go(input: "(;FF[4];B[ab];B[ba])")
+        let rootNode = go.tree.nodes[0]
+        let node = rootNode.children[0]
+
+        let point = GoPoint(column: 3, row: 3)
+        let definition: PropertyDefinition<Go, GoPoint> = .black
+        let newNode = Node<Go>(properties: [Property(definition, value: point)])
+        node.children.append(newNode)
+
+        #expect(go.tree.convertToSGF() == "(;FF[4];B[ab](;B[ba])(;B[cc]))")
+    }
+}