feat(GraphQLAPIAdapter): Add variadic generic initializer for network observers

This introduces a new initializer for `GraphQLAPIAdapter` that leverages Swift 5.9's variadic generics, allowing multiple `GraphQLNetworkObserver` instances to be passed directly without being wrapped in an array. This improves API ergonomics and simplifies usage. The `swift-tools-version` has been updated to 5.9 accordingly.

Author: Šimon Šesták

Sources/GraphQLAPIKit/GraphQLAPIAdapter.swift

@@ -38,11 +38,37 @@ public protocol GraphQLAPIAdapterProtocol: AnyObject {
 public final class GraphQLAPIAdapter: GraphQLAPIAdapterProtocol {
     private let apollo: ApolloClientProtocol
 
+    public init<each Observer: GraphQLNetworkObserver>(
+        url: URL,
+        urlSessionConfiguration: URLSessionConfiguration = .default,
+        defaultHeaders: [String: String] = [:],
+        networkObservers: repeat each Observer
+    ) {
+        var observers: [any GraphQLNetworkObserver] = []
+        repeat observers.append(each networkObservers)
+
+        let provider = NetworkInterceptorProvider(
+            client: URLSessionClient(sessionConfiguration: urlSessionConfiguration),
+            defaultHeaders: defaultHeaders,
+            networkObservers: observers
+        )
+
+        let networkTransport = RequestChainNetworkTransport(
+            interceptorProvider: provider,
+            endpointURL: url
+        )
+
+        self.apollo = ApolloClient(
+            networkTransport: networkTransport,
+            store: ApolloStore()
+        )
+    }
+
     public init(
         url: URL,
         urlSessionConfiguration: URLSessionConfiguration = .default,
         defaultHeaders: [String: String] = [:],
-        networkObservers: [any GraphQLNetworkObserver] = []
+        networkObservers: [any GraphQLNetworkObserver]
     ) {
         let provider = NetworkInterceptorProvider(
             client: URLSessionClient(sessionConfiguration: urlSessionConfiguration),

Tests/GraphQLAPIKitTests/GraphQLAPIAdapterIntegrationTests.swift

@@ -175,7 +175,7 @@ final class GraphQLAPIAdapterIntegrationTests: XCTestCase {
             url: URL(string: "https://api.example.com/graphql")!,
             urlSessionConfiguration: mockSessionConfiguration(),
             defaultHeaders: defaultHeaders,
-            networkObservers: [observer]
+            networkObservers: observer
         )
 
         _ = adapter.fetch(query: MockQuery(), context: nil, queue: .main) { _ in
@@ -210,7 +210,7 @@ final class GraphQLAPIAdapterIntegrationTests: XCTestCase {
             url: URL(string: "https://api.example.com/graphql")!,
             urlSessionConfiguration: mockSessionConfiguration(),
             defaultHeaders: [:],
-            networkObservers: [observer]
+            networkObservers: observer
         )
 
         _ = adapter.fetch(query: MockQuery(), context: contextHeaders, queue: .main) { _ in
@@ -249,7 +249,7 @@ final class GraphQLAPIAdapterIntegrationTests: XCTestCase {
             url: URL(string: "https://api.example.com/graphql")!,
             urlSessionConfiguration: mockSessionConfiguration(),
             defaultHeaders: defaultHeaders,
-            networkObservers: [observer]
+            networkObservers: observer
         )
 
         _ = adapter.fetch(query: MockQuery(), context: contextHeaders, queue: .main) { _ in
@@ -285,7 +285,7 @@ final class GraphQLAPIAdapterIntegrationTests: XCTestCase {
             url: URL(string: "https://api.example.com/graphql")!,
             urlSessionConfiguration: mockSessionConfiguration(),
             defaultHeaders: defaultHeaders,
-            networkObservers: [observer1, observer2, observer3]
+            networkObservers: observer1, observer2, observer3
         )
 
         _ = adapter.fetch(query: MockQuery(), context: nil, queue: .main) { _ in
@@ -322,7 +322,7 @@ final class GraphQLAPIAdapterIntegrationTests: XCTestCase {
             url: URL(string: "https://api.example.com/graphql")!,
             urlSessionConfiguration: mockSessionConfiguration(),
             defaultHeaders: [:],
-            networkObservers: [observer]
+            networkObservers: observer
         )
 
         _ = adapter.fetch(query: MockQuery(), context: nil, queue: .main) { _ in