MBL-1382: Log more detailed errors when keychain fails (#2631)

Author: amy-at-kickstarter

Library/AppEnvironment.swift

@@ -335,6 +335,14 @@ public struct AppEnvironment: AppEnvironmentType {
     )
   }
 
+  private static func logKeychainError(_ error: KeychainError) {
+    Crashlytics.crashlytics().record(error: error.nsError)
+  }
+
+  private static func logUnknownError(_ error: Error) {
+    Crashlytics.crashlytics().record(error: error)
+  }
+
   internal static let accountNameForKeychain = "kickstarter_currently_logged_in_user"
 
   private static func storeOAuthTokenToKeychain(_ oauthToken: String) -> Bool {
@@ -346,8 +354,10 @@ public struct AppEnvironment: AppEnvironmentType {
     do {
       try Keychain.storePassword(oauthToken, forAccount: self.accountNameForKeychain)
       return true
+    } catch let error as KeychainError {
+      logKeychainError(error)
     } catch {
-      Crashlytics.crashlytics().record(error: error)
+      self.logUnknownError(error)
     }
 
     return false
@@ -361,8 +371,10 @@ public struct AppEnvironment: AppEnvironmentType {
 
     do {
       return try Keychain.fetchPassword(forAccount: self.accountNameForKeychain)
+    } catch let error as KeychainError {
+      logKeychainError(error)
     } catch {
-      Crashlytics.crashlytics().record(error: error)
+      self.logUnknownError(error)
     }
 
     return nil
@@ -374,8 +386,10 @@ public struct AppEnvironment: AppEnvironmentType {
     do {
       try Keychain.deletePassword(forAccount: self.accountNameForKeychain)
       return true
+    } catch let error as KeychainError {
+      logKeychainError(error)
     } catch {
-      Crashlytics.crashlytics().record(error: error)
+      self.logUnknownError(error)
     }
 
     return false

Library/Keychain.swift

@@ -5,7 +5,7 @@ public enum KeychainError: Error {
   case unexpectedStatus(OSStatus)
   case unableToDecodePasswordData
 
-  public var errorMessage: String {
+  private var errorMessage: String {
     switch self {
     case let .unexpectedStatus(status):
       let errString = SecCopyErrorMessageString(status, nil) as String?
@@ -14,6 +14,25 @@ public enum KeychainError: Error {
       return "Unable to decode password data from keychain."
     }
   }
+
+  private var errorCode: Int {
+    switch self {
+    case let .unexpectedStatus(status):
+      return Int(status)
+    case .unableToDecodePasswordData:
+      return -999
+    }
+  }
+
+  public var nsError: NSError {
+    return NSError(
+      domain: "Library.KeychainError",
+      code: self.errorCode,
+      userInfo: [
+        NSLocalizedDescriptionKey: self.errorMessage
+      ]
+    )
+  }
 }
 
 public struct Keychain {