Support token providers in Bearer Auth middleware.

README.md

@@ -54,6 +54,14 @@ let client = Client(
 )
 ```
 
+Tokens expire after 20 minutes at most. For longer-lived clients, pass a token provider instead, which is called on every request:
+
+```swift
+BearerAuthMiddleware {
+    try await tokenStore.validToken()
+}
+```
+
 ### Making API Calls
 
 The `Client` conforms to `APIProtocol`, which defines a method for every endpoint in the App Store Connect API. Each method accepts an `Input` value and returns an `Output` value with the response.

Sources/ASConnectService/Catalogs/ASConnectService.docc/Library.md

@@ -25,6 +25,14 @@ let client = Client(
 )
 ```
 
+Tokens expire after 20 minutes at most. For longer-lived clients, pass a token provider instead, which is called on every request:
+
+```swift
+BearerAuthMiddleware {
+    try await tokenStore.validToken()
+}
+```
+
 ### Making API Calls
 
 The ``Client`` conforms to ``APIProtocol``, which defines a method for every endpoint in the App Store Connect API. Each method accepts an `Input` value and returns an `Output` value with the response.

Sources/ASConnectService/Sources/Public/Middlewares/BearerAuthMiddleware.swift

@@ -13,10 +13,6 @@
 // ===----------------------------------------------------------------------===
 
 import struct Foundation.URL
-import struct Foundation.URLComponents
-import struct Foundation.URLQueryItem
-import struct HTTPTypes.HTTPField
-import struct HTTPTypes.HTTPFields
 import struct HTTPTypes.HTTPRequest
 import struct HTTPTypes.HTTPResponse
 import protocol OpenAPIRuntime.ClientMiddleware
@@ -30,21 +26,43 @@ import class OpenAPIRuntime.HTTPBody
 ///
 /// ## Usage
 ///
+/// Provide a fixed token:
+///
 /// ```swift
 /// let middleware = BearerAuthMiddleware(token: "your-jwt-token")
 /// ```
+///
+/// Tokens expire after 20 minutes at most, so long-lived clients should provide a token provider instead:
+///
+/// ```swift
+/// let middleware = BearerAuthMiddleware {
+///     try await tokenStore.validToken()
+/// }
+/// ```
 public struct BearerAuthMiddleware {
     // MARK: Properties
 
-    /// The Bearer token to include in the `Authorization` header of each request.
+    /// The closure that provides the Bearer token for each request.
-    private let token: String
+    private let tokenProvider: @Sendable () async throws -> String
 
     // MARK: Initializers
 
-    /// Creates a new middleware instance with the given Bearer token.
+    /// Creates a new middleware instance with a fixed Bearer token.
-    /// - Parameter token: A JSON Web Token (JWT) string used to authenticate requests to the App Store Connect API.
+    /// - Parameter token: A JSON Web Token (JWT) used to authenticate requests to the App Store Connect API.
-    init(token: String) {
+    public init(
-        self.token = token
+        token: String
+    ) {
+        self.init { token }
+    }
+
+    /// Creates a new middleware instance that asks for a Bearer token on every request.
+    ///
+    /// If the provider throws, the error is rethrown and the request is not sent.
+    /// - Parameter tokenProvider: A closure that returns a valid JSON Web Token (JWT).
+    public init(
+        tokenProvider: @escaping @Sendable () async throws -> String
+    ) {
+        self.tokenProvider = tokenProvider
     }
 }
 
@@ -68,6 +86,8 @@ extension BearerAuthMiddleware: ClientMiddleware {
         operationID: String,
         next: @Sendable (HTTPRequest, HTTPBody?, URL) async throws -> (HTTPResponse, HTTPBody?)
     ) async throws -> (HTTPResponse, HTTPBody?) {
+        let token = try await tokenProvider()
+
         var request = request
         request.headerFields[.authorization] = "Bearer \(token)"
 

Tests/ASConnectService/Cases/Public/Middlewares/BearerAuthMiddlewareTests.swift

@@ -3,7 +3,8 @@ import HTTPTypes
 import OpenAPIRuntime
 import Testing
 
-@testable import ASConnectService
+// A non-testable import ensures that the middleware can be created from outside the module.
+import ASConnectService
 
 @Suite("BearerAuthMiddleware")
 struct BearerAuthMiddlewareTests {
@@ -112,6 +113,67 @@ struct BearerAuthMiddlewareTests {
             }
         )
     }
+
+    @Test("Asks the token provider for a token on every request")
+    func asksTokenProviderOnEveryRequest() async throws {
+        let tokens = TokenSequence()
+        let middleware = BearerAuthMiddleware {
+            await tokens.next()
+        }
+
+        for expectedToken in ["token-1", "token-2"] {
+            _ = try await middleware.intercept(
+                .get,
+                body: nil,
+                baseURL: .base,
+                operationID: "listApps",
+                next: { interceptedRequest, _, _ in
+                    #expect(interceptedRequest.headerFields[.authorization] == "Bearer \(expectedToken)")
+
+                    return (HTTPResponse(status: .ok), nil)
+                }
+            )
+        }
+    }
+
+    @Test("Rethrows the token provider error without calling the next handler")
+    func rethrowsTokenProviderError() async throws {
+        let middleware = BearerAuthMiddleware {
+            throw TokenError.expired
+        }
+
+        await #expect(throws: TokenError.expired) {
+            _ = try await middleware.intercept(
+                .get,
+                body: nil,
+                baseURL: .base,
+                operationID: "listApps",
+                next: { _, _, _ in
+                    Issue.record("The next handler should not be called when the token provider throws")
+
+                    return (HTTPResponse(status: .ok), nil)
+                }
+            )
+        }
+    }
+}
+
+// MARK: - Helpers
+
+/// An actor that returns a new token every time it is asked for one.
+private actor TokenSequence {
+    private var count = 0
+
+    func next() -> String {
+        count += 1
+
+        return "token-\(count)"
+    }
+}
+
+/// An error thrown by a token provider.
+private enum TokenError: Error {
+    case expired
 }
 
 // MARK: - HTTPRequest+Samples