Wrap .org XML RPC error enum in an Error-conforming struct

Jumping through this hoop was necessary to avoid the Swift compiler automatically generating an error domain for the `Error` and making it impossible to successfully redefine the domain at the `CustomNSError` conformance site.
wordpress-mobile · Apr 17, 2024 · ac15e9a · ac15e9a
1 parent f6f0c1c
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -30,6 +30,24 @@ _None._
 
 -->
 
+## Unreleased
+
+### Breaking Changes
+
+- The Objective-C-visible `WordPressOrgXMLRPCError` `enum` has been renamed to `WordPressOrgXMLRPCErrorCode` [#790]
+
+### New Features
+
+_None._
+
+### Bug Fixes
+
+_None._
+
+### Internal Changes
+
+_None._
+
 ## 17.0.0
 
 ### Breaking Changes

diff --git a/Sources/CoreAPI/WordPressOrgXMLRPCApi.swift b/Sources/CoreAPI/WordPressOrgXMLRPCApi.swift
@@ -288,43 +288,6 @@ private class SessionDelegate: NSObject, URLSessionDelegate {
         }
     }
 }
-
-// Hack to avoid the Swift compiler generating a domain constant for us that would then conflict with the one we define in APIInterface.
-// The automatic generation occurs, as far as I can tell, because of @objc and Error, neither of which we can remove.
-// Reminder: We define our own constant for the domain so that we can conform WordPressOrgXMLRPCApiError to CustomNSError.
-typealias WordPressOrgXMLRPCApiError = WordPressOrgXMLRPCAPIError
-
-/// Error constants for the WordPress XML-RPC API
-@objc public enum WordPressOrgXMLRPCAPIError: Int, Error, CaseIterable {
-    /// An error HTTP status code was returned.
-    case httpErrorStatusCode
-    /// The serialization of the request failed.
-    case requestSerializationFailed
-    /// The serialization of the response failed.
-    case responseSerializationFailed
-    /// An unknown error occurred.
-    case unknown
-}
-
-extension WordPressOrgXMLRPCApiError: LocalizedError {
-    public var errorDescription: String? {
-        return NSLocalizedString("There was a problem communicating with the site.", comment: "A general error message shown to the user when there was an API communication failure.")
-    }
-
-    public var failureReason: String? {
-        switch self {
-        case .httpErrorStatusCode:
-            return NSLocalizedString("An HTTP error code was returned.", comment: "A failure reason for when an error HTTP status code was returned from the site.")
-        case .requestSerializationFailed:
-            return NSLocalizedString("The serialization of the request failed.", comment: "A failure reason for when the request couldn't be serialized.")
-        case .responseSerializationFailed:
-            return NSLocalizedString("The serialization of the response failed.", comment: "A failure reason for when the response couldn't be serialized.")
-        case .unknown:
-            return NSLocalizedString("An unknown error occurred.", comment: "A failure reason for when the error that occured wasn't able to be determined.")
-        }
-    }
-}
-
 public struct WordPressOrgXMLRPCApiFault: LocalizedError, HTTPURLResponseProviding {
     public var response: HTTPAPIResponse<Data>
     public let code: Int?
@@ -352,7 +315,13 @@ private extension WordPressAPIResult<HTTPAPIResponse<Data>, WordPressOrgXMLRPCAp
         // https://github.com/wordpress-mobile/WordPressKit-iOS/blob/11.0.0/WordPressKit/WordPressOrgXMLRPCApi.swift#L265
         flatMap { response in
             guard let contentType = response.response.allHeaderFields["Content-Type"] as? String else {
-                return .failure(.unparsableResponse(response: response.response, body: response.body, underlyingError: WordPressOrgXMLRPCApiError.unknown))
+                return .failure(
+                    .unparsableResponse(
+                        response: response.response,
+                        body: response.body,
+                        underlyingError: WordPressOrgXMLRPCApiError(code: .unknown)
+                    )
+                )
             }
 
             if (400..<600).contains(response.response.statusCode) {
@@ -366,7 +335,13 @@ private extension WordPressAPIResult<HTTPAPIResponse<Data>, WordPressOrgXMLRPCAp
             }
 
             guard contentType.hasPrefix("application/xml") || contentType.hasPrefix("text/xml") else {
-                return .failure(.unparsableResponse(response: response.response, body: response.body, underlyingError: WordPressOrgXMLRPCApiError.unknown))
+                return .failure(
+                    .unparsableResponse(
+                        response: response.response,
+                        body: response.body,
+                        underlyingError: WordPressOrgXMLRPCApiError(code: .unknown)
+                    )
+                )
             }
 
             guard let decoder = WPXMLRPCDecoder(data: response.body) else {
@@ -418,7 +393,7 @@ private extension WordPressAPIError where EndpointError == WordPressOrgXMLRPCApi
             data = fault.response.body
             statusCode = nil
         case let .unacceptableStatusCode(response, body):
-            error = WordPressOrgXMLRPCApiError.httpErrorStatusCode as NSError
+            error = WordPressOrgXMLRPCApiError(code: .httpErrorStatusCode) as NSError
             data = body
             statusCode = response.statusCode
         case let .unparsableResponse(_, body, underlyingError):

diff --git a/Sources/CoreAPI/WordPressOrgXMLRPCApiError+NSErrorBridge.swift b/Sources/CoreAPI/WordPressOrgXMLRPCApiError+NSErrorBridge.swift
@@ -8,7 +8,7 @@ extension WordPressOrgXMLRPCApiError: CustomNSError {
 
     public static let errorDomain = WordPressOrgXMLRPCApiErrorDomain
 
-    public var errorCode: Int { self.rawValue }
+    public var errorCode: Int { code.rawValue }
 
     public var errorUserInfo: [String: Any] { [:] }
 }
diff --git a/Sources/CoreAPI/WordPressOrgXMLRPCApiError.swift b/Sources/CoreAPI/WordPressOrgXMLRPCApiError.swift
@@ -0,0 +1,39 @@
+import Foundation
+
+/// Error constants for the WordPress XML-RPC API
+@objc public enum WordPressOrgXMLRPCApiErrorCode: Int, CaseIterable {
+    /// An error HTTP status code was returned.
+    case httpErrorStatusCode
+    /// The serialization of the request failed.
+    case requestSerializationFailed
+    /// The serialization of the response failed.
+    case responseSerializationFailed
+    /// An unknown error occurred.
+    case unknown
+}
+
+public struct WordPressOrgXMLRPCApiError: Error {
+    let code: WordPressOrgXMLRPCApiErrorCode
+}
+
+extension WordPressOrgXMLRPCApiError: LocalizedError {
+    public var errorDescription: String? {
+        return NSLocalizedString(
+            "There was a problem communicating with the site.",
+            comment: "A general error message shown to the user when there was an API communication failure."
+        )
+    }
+
+    public var failureReason: String? {
+        switch code {
+        case .httpErrorStatusCode:
+            return NSLocalizedString("An HTTP error code was returned.", comment: "A failure reason for when an error HTTP status code was returned from the site.")
+        case .requestSerializationFailed:
+            return NSLocalizedString("The serialization of the request failed.", comment: "A failure reason for when the request couldn't be serialized.")
+        case .responseSerializationFailed:
+            return NSLocalizedString("The serialization of the response failed.", comment: "A failure reason for when the response couldn't be serialized.")
+        case .unknown:
+            return NSLocalizedString("An unknown error occurred.", comment: "A failure reason for when the error that occured wasn't able to be determined.")
+        }
+    }
+}
diff --git a/Tests/CoreAPITests/WordPressOrgXMLRPCApiErrorTests.swift b/Tests/CoreAPITests/WordPressOrgXMLRPCApiErrorTests.swift
@@ -9,8 +9,8 @@ import XCTest
 class WordPressOrgXMLRPCApiErrorTests: XCTestCase {
 
     func testNSErrorBridging() throws {
-        for error in WordPressOrgXMLRPCApiError.allCases {
-            let xmlRPCError = try XCTUnwrap(WordPressOrgXMLRPCApiError(rawValue: error.rawValue))
+        for error in WordPressOrgXMLRPCApiErrorCode.allCases {
+            let xmlRPCError = try XCTUnwrap(WordPressOrgXMLRPCApiError(code: error))
             let apiError = WordPressAPIError.endpointError(xmlRPCError)
             let newNSError = apiError as NSError
 

diff --git a/Tests/CoreAPITests/WordPressOrgXMLRPCApiTests.swift b/Tests/CoreAPITests/WordPressOrgXMLRPCApiTests.swift
@@ -65,7 +65,7 @@ class WordPressOrgXMLRPCApiTests: XCTestCase {
             failure: { (error, _) in
                 expect.fulfill()
                 XCTAssertEqual(error.domain, WordPressOrgXMLRPCApiErrorDomain)
-                XCTAssertEqual(error.code, WordPressOrgXMLRPCApiError.httpErrorStatusCode.rawValue)
+                XCTAssertEqual(error.code, WordPressOrgXMLRPCApiErrorCode.httpErrorStatusCode.rawValue)
                 XCTAssertEqual(error.localizedFailureReason, "An HTTP error code 404 was returned.")
                 XCTAssertNotNil(error.userInfo[WordPressOrgXMLRPCApi.WordPressOrgXMLRPCApiErrorKeyData as String])
                 XCTAssertNotNil(error.userInfo[WordPressOrgXMLRPCApi.WordPressOrgXMLRPCApiErrorKeyStatusCode as String])
@@ -119,10 +119,10 @@ class WordPressOrgXMLRPCApiTests: XCTestCase {
             failure: { (error, _) in
                 expect.fulfill()
 
-                XCTAssertTrue(error is WordPressOrgXMLRPCApiError)
                 XCTAssertEqual(error.domain, WordPressOrgXMLRPCApiErrorDomain)
-                XCTAssertEqual(error.code, WordPressOrgXMLRPCApiError.unknown.rawValue)
-                XCTAssertEqual(error.localizedFailureReason, WordPressOrgXMLRPCApiError.unknown.failureReason)
+                let errorUnknonw = WordPressOrgXMLRPCApiError(code: .unknown)
+                XCTAssertEqual(error.code, errorUnknonw.code.rawValue)
+                XCTAssertEqual(error.localizedFailureReason, errorUnknonw.failureReason)
                 XCTAssertNotNil(error.userInfo[WordPressOrgXMLRPCApi.WordPressOrgXMLRPCApiErrorKeyData as String])
                 XCTAssertNil(error.userInfo[WordPressOrgXMLRPCApi.WordPressOrgXMLRPCApiErrorKeyStatusCode as String])
             }

diff --git a/WordPressKit.xcodeproj/project.pbxproj b/WordPressKit.xcodeproj/project.pbxproj
@@ -70,6 +70,7 @@
 		3F8308A729EE683500354497 /* ActivityTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3F8308A629EE683500354497 /* ActivityTests.swift */; };
 		3FA4258F2BCCFDA6007539BF /* WordPressComRestApiErrorDomain.h in Headers */ = {isa = PBXBuildFile; fileRef = 3FA4258E2BCCFDA6007539BF /* WordPressComRestApiErrorDomain.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		3FA425A72BCF7EDC007539BF /* WordPressOrgXMLRPCApiErrorDomain.h in Headers */ = {isa = PBXBuildFile; fileRef = 3FA425A62BCF7E7C007539BF /* WordPressOrgXMLRPCApiErrorDomain.h */; settings = {ATTRIBUTES = (Public, ); }; };
+		3FA425A92BCF8721007539BF /* WordPressOrgXMLRPCApiError.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3FA425A82BCF8721007539BF /* WordPressOrgXMLRPCApiError.swift */; };
 		3FB8642C2888089F003A86BE /* BuildkiteTestCollector in Frameworks */ = {isa = PBXBuildFile; productRef = 3FB8642B2888089F003A86BE /* BuildkiteTestCollector */; };
 		3FD634E52BC3A55F00CEDF5E /* WordPressOrgXMLRPCValidator.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3FD634E32BC3A55F00CEDF5E /* WordPressOrgXMLRPCValidator.swift */; };
 		3FD634E62BC3A55F00CEDF5E /* Date+WordPressCom.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3FD634E42BC3A55F00CEDF5E /* Date+WordPressCom.swift */; };
@@ -821,6 +822,7 @@
 		3F8308A629EE683500354497 /* ActivityTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ActivityTests.swift; sourceTree = "<group>"; };
 		3FA4258E2BCCFDA6007539BF /* WordPressComRestApiErrorDomain.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = WordPressComRestApiErrorDomain.h; sourceTree = "<group>"; };
 		3FA425A62BCF7E7C007539BF /* WordPressOrgXMLRPCApiErrorDomain.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = WordPressOrgXMLRPCApiErrorDomain.h; sourceTree = "<group>"; };
+		3FA425A82BCF8721007539BF /* WordPressOrgXMLRPCApiError.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = WordPressOrgXMLRPCApiError.swift; sourceTree = "<group>"; };
 		3FB8642D288813E9003A86BE /* UnitTests.xctestplan */ = {isa = PBXFileReference; lastKnownFileType = text; path = UnitTests.xctestplan; sourceTree = "<group>"; };
 		3FD634E32BC3A55F00CEDF5E /* WordPressOrgXMLRPCValidator.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = WordPressOrgXMLRPCValidator.swift; sourceTree = "<group>"; };
 		3FD634E42BC3A55F00CEDF5E /* Date+WordPressCom.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = "Date+WordPressCom.swift"; sourceTree = "<group>"; };
@@ -2143,6 +2145,7 @@
 				3FE2E97A2BC3A332002CA2E1 /* WordPressComRestApi.swift */,
 				4A05E7992B2FDC3200C25E3B /* WordPressOrgRestApi.swift */,
 				93BD27791EE73944002BB00B /* WordPressOrgXMLRPCApi.swift */,
+				3FA425A82BCF8721007539BF /* WordPressOrgXMLRPCApiError.swift */,
 				3F6128122BCB31660063810D /* WordPressOrgXMLRPCApiError+NSErrorBridge.swift */,
 				3FD634E32BC3A55F00CEDF5E /* WordPressOrgXMLRPCValidator.swift */,
 				93BD277B1EE73944002BB00B /* WordPressRSDParser.swift */,
@@ -3314,6 +3317,7 @@
 				9AB6D647218705E90008F274 /* RemoteDiff.swift in Sources */,
 				93BD277C1EE73944002BB00B /* HTTPAuthenticationAlertController.swift in Sources */,
 				7433BC011EFC4505002D9E92 /* PlanServiceRemote.swift in Sources */,
+				3FA425A92BCF8721007539BF /* WordPressOrgXMLRPCApiError.swift in Sources */,
 				4041405E220F9EF500CF7C5B /* StatsDotComFollowersInsight.swift in Sources */,
 				74650F721F0EA1A700188EDB /* GravatarServiceRemote.swift in Sources */,
 				B5969E1D20A49AC4005E9DF1 /* NSString+MD5.m in Sources */,