Equatable support on node

Sources/SGFKit/Collection.swift

@@ -47,6 +47,10 @@ extension Collection: NodeProtocol {
     func node(treeStructureDidUpdated number: Int?) {
         refreshStructure()
     }
+
+    public static func == (lhs: Collection<Game>, rhs: Collection<Game>) -> Bool {
+        lhs.nodes == rhs.nodes
+    }
 }
 
 private final class NumberPublisher {

Sources/SGFKit/Node.swift

@@ -1,4 +1,4 @@
-protocol NodeProtocol<Game>: AnyObject {
+protocol NodeProtocol<Game>: AnyObject, Equatable {
     associatedtype Game: SGFKit.Game
 
     var number: Int? { get }
@@ -9,6 +9,7 @@ protocol NodeProtocol<Game>: AnyObject {
 
 /// A node object for SGF.
 public final class Node<Game: SGFKit.Game> {
+
     /// A unique number for the node in the collection.
     ///
     /// The numbering rule follows [the official documents rule](https://www.red-bean.com/sgf/sgf4.html#1)
@@ -105,6 +106,12 @@ extension Node: NodeProtocol {
     func node(treeStructureDidUpdated index: Int?) {
         parent?.node(treeStructureDidUpdated: index)
     }
+
+    public static func == (lhs: Node<Game>, rhs: Node<Game>) -> Bool {
+        lhs.number == rhs.number
+        && lhs.children == rhs.children
+        && lhs.properties == rhs.properties
+    }
 }
 
 /// A struct indicating a raw property of a node.

Tests/SGFKitTests/NodeTests.swift

@@ -0,0 +1,94 @@
+@testable import SGFKit
+import Testing
+
+@Suite
+struct NodeTests {
+
+    // MARK: - Equatable Tests
+
+    @Test
+    func equalityWithSameProperties() throws {
+        let property1 = Property(identifier: "B", values: [.single("cc")])
+        let node1 = Node<Go>(properties: [property1])
+
+        let property2 = Property(identifier: "B", values: [.single("cc")])
+        let node2 = Node<Go>(properties: [property2])
+
+        #expect(node1 == node2)
+    }
+
+    @Test
+    func equalityWithDifferentProperties() throws {
+        let property1 = Property(identifier: "B", values: [.single("cc")])
+        let node1 = Node<Go>(properties: [property1])
+
+        let property2 = Property(identifier: "B", values: [.single("dd")])
+        let node2 = Node<Go>(properties: [property2])
+
+        #expect(node1 != node2)
+    }
+
+    @Test
+    func equalityWithDifferentNumbers() throws {
+        let property1 = Property(identifier: "B", values: [.single("cc")])
+        let node1 = Node<Go>(number: 1, properties: [property1])
+
+        let property2 = Property(identifier: "B", values: [.single("cc")])
+        let node2 = Node<Go>(number: 2, properties: [property2])
+
+        #expect(node1 != node2)
+    }
+
+    @Test
+    func equalityWithSameChildren() throws {
+        let childProperty1 = Property(identifier: "W", values: [.single("dd")])
+        let child1 = Node<Go>(properties: [childProperty1])
+
+        let property1 = Property(identifier: "B", values: [.single("cc")])
+        let node1 = Node<Go>(properties: [property1])
+        node1.children = [child1]
+
+        let childProperty2 = Property(identifier: "W", values: [.single("dd")])
+        let child2 = Node<Go>(properties: [childProperty2])
+
+        let property2 = Property(identifier: "B", values: [.single("cc")])
+        let node2 = Node<Go>(properties: [property2])
+        node2.children = [child2]
+
+        #expect(node1 == node2)
+    }
+
+    @Test
+    func equalityWithDifferentChildren() throws {
+        let childProperty1 = Property(identifier: "W", values: [.single("dd")])
+        let child1 = Node<Go>(properties: [childProperty1])
+
+        let property1 = Property(identifier: "B", values: [.single("cc")])
+        let node1 = Node<Go>(properties: [property1])
+        node1.children = [child1]
+
+        let childProperty2 = Property(identifier: "W", values: [.single("ee")])
+        let child2 = Node<Go>(properties: [childProperty2])
+
+        let property2 = Property(identifier: "B", values: [.single("cc")])
+        let node2 = Node<Go>(properties: [property2])
+        node2.children = [child2]
+
+        #expect(node1 != node2)
+    }
+
+    @Test
+    func equalityWithDifferentChildrenCount() throws {
+        let childProperty1 = Property(identifier: "W", values: [.single("dd")])
+        let child1 = Node<Go>(properties: [childProperty1])
+
+        let property1 = Property(identifier: "B", values: [.single("cc")])
+        let node1 = Node<Go>(properties: [property1])
+        node1.children = [child1]
+
+        let property2 = Property(identifier: "B", values: [.single("cc")])
+        let node2 = Node<Go>(properties: [property2])
+
+        #expect(node1 != node2)
+    }
+}