Add URLEncodedFormError.description, update array value in error

Author: adam-fowler

Sources/Hummingbird/Codable/URLEncodedForm/URLEncodedFormNode.swift

@@ -12,7 +12,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-public struct URLEncodedFormError: Error {
+/// Error thrown from parsing URLEncoded forms
+public struct URLEncodedFormError: Error, CustomStringConvertible {
     public struct Code: Sendable, Equatable {
         fileprivate enum Internal: Equatable {
             case duplicateKeys
@@ -55,6 +56,20 @@ public struct URLEncodedFormError: Error {
     }
 }
 
+extension URLEncodedFormError {
+    public var description: String {
+        switch self.code.value {
+        case .duplicateKeys: "Found duplicate keys with name '\(self.value)'"
+        case .addingToInvalidType: "Adding array or dictionary value to non array or dictionary value '\(self.value)'"
+        case .failedToPercentDecode: "Failed to percent decode '\(self.value)'"
+        case .corruptKeyValue: "Parsing dictionary key value failed '\(self.value)'"
+        case .notSupported: "URLEncoded form structure not supported '\(self.value)'"
+        case .invalidArrayIndex: "Invalid array index '\(self.value)'"
+        case .unexpectedError:
+            "Unexpected error with '\(self.value)' please add an issue at https://github.com/hummingbird-project/hummingbird/issues"
+        }
+    }
+}
 /// Internal representation of URL encoded form data used by both encode and decode
 enum URLEncodedFormNode: CustomStringConvertible, Equatable {
     /// holds a value
@@ -142,7 +157,7 @@ enum URLEncodedFormNode: CustomStringConvertible, Equatable {
             }
         case (.array(let array), .arrayWithIndices(let index)):
             guard keys.count == 0, array.values.count == index else {
-                throw URLEncodedFormError(code: .invalidArrayIndex, value: key)
+                throw URLEncodedFormError(code: .invalidArrayIndex, value: "\(key)[\(index)]")
             }
             array.values.append(.leaf(value))
         case (_, .arrayWithIndices), (_, .array):

Tests/HummingbirdTests/URLEncodedForm/URLDecoderTests.swift

@@ -141,7 +141,7 @@ final class URLDecodedFormDecoderTests: XCTestCase {
                 return
             }
             XCTAssertEqual(error.code, .invalidArrayIndex)
-            XCTAssertEqual(error.value, "arr")
+            XCTAssertEqual(error.value, "arr[2]")
         }
     }
 
@@ -295,7 +295,7 @@ final class URLDecodedFormDecoderTests: XCTestCase {
         self.testForm(ArrayDecoding(array: [], map: [:], a: 3), query: "a=3")
     }
 
-    func testDecodeErrors() throws {
+    func testParsingErrors() throws {
         struct Input1: Decodable {}
         XCTAssertThrowsError(try URLEncodedFormDecoder().decode(Input1.self, from: "someField=1&someField=2")) { error in
             guard let error = try? XCTUnwrap(error as? URLEncodedFormError) else {
@@ -305,6 +305,14 @@ final class URLDecodedFormDecoderTests: XCTestCase {
             XCTAssertEqual(error.code, .duplicateKeys)
             XCTAssertEqual(error.value, "someField")
         }
+        XCTAssertThrowsError(try URLEncodedFormDecoder().decode(Input1.self, from: "someField[]=1&someField=2")) { error in
+            guard let error = try? XCTUnwrap(error as? URLEncodedFormError) else {
+                XCTFail()
+                return
+            }
+            XCTAssertEqual(error.code, .duplicateKeys)
+            XCTAssertEqual(error.value, "someField")
+        }
         XCTAssertThrowsError(try URLEncodedFormDecoder().decode(Input1.self, from: "someField=1&someField[]=2")) { error in
             guard let error = try? XCTUnwrap(error as? URLEncodedFormError) else {
                 XCTFail()
@@ -321,5 +329,13 @@ final class URLDecodedFormDecoderTests: XCTestCase {
             XCTAssertEqual(error.code, .addingToInvalidType)
             XCTAssertEqual(error.value, "someField")
         }
+        XCTAssertThrowsError(try URLEncodedFormDecoder().decode(Input1.self, from: "someField[=2")) { error in
+            guard let error = try? XCTUnwrap(error as? URLEncodedFormError) else {
+                XCTFail()
+                return
+            }
+            XCTAssertEqual(error.code, .corruptKeyValue)
+            XCTAssertEqual(error.value, "someField[")
+        }
     }
 }