feat: add .bearer credential for OAuth access tokens (#4)

Sources/ForgejoKit/Services/ForgejoClient.swift

@@ -7,6 +7,7 @@ public final class ForgejoClient: Sendable {
     private enum AuthCredential: Sendable {
         case basic(base64: String)
         case token(String)
+        case bearer(String)
     }
 
     private let credential: AuthCredential
@@ -48,6 +49,21 @@ public final class ForgejoClient: Sendable {
         )
     }
 
+    /// Creates a client authenticated with an OAuth2 access token.
+    ///
+    /// OAuth2 access tokens are sent with the `Authorization: Bearer` scheme,
+    /// unlike personal access tokens which use `Authorization: token`.
+    public convenience init(
+        serverURL: String, username: String, bearerToken: String,
+        allowSelfSignedCertificates: Bool = false,
+    ) {
+        self.init(
+            serverURL: serverURL, username: username,
+            credential: .bearer(bearerToken),
+            allowSelfSignedCertificates: allowSelfSignedCertificates,
+        )
+    }
+
     public static func login(
         serverURL: String, username: String, password: String,
         allowSelfSignedCertificates: Bool = false,
@@ -125,11 +141,19 @@ public final class ForgejoClient: Sendable {
     }
 
     private func applyAuthHeader(to request: inout URLRequest) {
+        request.setValue(authorizationHeaderValue, forHTTPHeaderField: "Authorization")
+    }
+
+    /// The `Authorization` header value for this client's credential.
+    /// Exposed internally so tests can assert the scheme without issuing a request.
+    var authorizationHeaderValue: String {
         switch credential {
         case let .basic(base64):
-            request.setValue("Basic \(base64)", forHTTPHeaderField: "Authorization")
+            "Basic \(base64)"
         case let .token(token):
-            request.setValue("token \(token)", forHTTPHeaderField: "Authorization")
+            "token \(token)"
+        case let .bearer(token):
+            "Bearer \(token)"
         }
     }
 

Tests/ForgejoKitTests/BearerCredentialTests.swift

@@ -0,0 +1,27 @@
+import Foundation
+import Testing
+@testable import ForgejoKit
+
+struct BearerCredentialTests {
+    @Test func bearerCredentialUsesBearerScheme() {
+        let client = ForgejoClient(
+            serverURL: "https://codeberg.org", username: "octocat", bearerToken: "abc123",
+        )
+        #expect(client.authorizationHeaderValue == "Bearer abc123")
+    }
+
+    @Test func tokenCredentialStillUsesTokenScheme() {
+        let client = ForgejoClient(
+            serverURL: "https://codeberg.org", username: "octocat", token: "abc123",
+        )
+        #expect(client.authorizationHeaderValue == "token abc123")
+    }
+
+    @Test func basicCredentialUsesBasicScheme() {
+        let client = ForgejoClient(
+            serverURL: "https://codeberg.org", username: "octocat", password: "pw",
+        )
+        let expected = "Basic " + Data("octocat:pw".utf8).base64EncodedString()
+        #expect(client.authorizationHeaderValue == expected)
+    }
+}