fix: add an error when trying to generate twitch http headers without…

… client ID

Sources/Twitch/API/Helix.swift

@@ -38,7 +38,7 @@ public final class Helix {
 
     var urlRequest = URLRequest(url: url)
     urlRequest.httpMethod = method
-    urlRequest.allHTTPHeaderFields = authentication.httpHeaders()
+    urlRequest.allHTTPHeaderFields = try? authentication.httpHeaders()
 
     return try await self.send(urlRequest)
   }

Sources/Twitch/TwitchCredentials.swift

@@ -5,6 +5,7 @@ public struct TwitchCredentials {
   internal let clientID: String?
 
   public init(oAuth: String, clientID: String? = nil) {
+    // assure that the stored token always starts with "oauth:"
     if !oAuth.starts(with: oAuthPrefix) {
       self.oAuth = oAuthPrefix + oAuth
     } else {
@@ -18,14 +19,18 @@ public struct TwitchCredentials {
     return String(oAuth.dropFirst(oAuthPrefix.count))
   }
 
-  internal func httpHeaders() -> [String: String] {
+  internal func httpHeaders() throws -> [String: String] {
+    guard let clientID = self.clientID else {
+      throw CredentialError.missingClientID
+    }
+
     var headers: [String: String] = [:]
-    headers.updateValue("Bearer " + self.cleanOAuth, forKey: "Authorization")
 
-    if let clientID = self.clientID {
-      headers.updateValue(clientID, forKey: "Client-Id")
-    }
+    headers.updateValue(clientID, forKey: "Client-Id")
+    headers.updateValue("Bearer \(self.cleanOAuth)", forKey: "Authorization")
 
     return headers
   }
 }
+
+public enum CredentialError: Error { case missingClientID }

Tests/TwitchTests/AuthenticationTests.swift

@@ -26,19 +26,26 @@ class AuthenticationTests: XCTestCase {
     XCTAssertEqual(auth.oAuth, "oauth:" + oAuth)
   }
 
-  func testHTTPHeaders() {
+  func testHTTPHeaders() throws {
     let oAuth = "abcdefghijklmnop"
     let clientID = "1234567890"
     let auth = TwitchCredentials(oAuth: oAuth, clientID: clientID)
 
-    let headers = auth.httpHeaders()
+    let headers = try auth.httpHeaders()
 
     XCTAssert(
       headers.contains(where: {
-        $0.key == "Authorization" && $0.value == "Bearer " + oAuth
+        $0.key == "Authorization" && $0.value == "Bearer \(oAuth)"
       }))
     XCTAssert(
       headers.contains(where: { $0.key == "Client-Id" && $0.value == clientID })
     )
   }
+
+  func testHTTPHeadersWithoutClientId() {
+    let oAuth = "abcdefghijklmnop"
+    let auth = TwitchCredentials(oAuth: oAuth)
+
+    XCTAssertThrowsError(try auth.httpHeaders())
+  }
 }