Add PostgresDecodingError debugDescription (#358)

Author: gwynne

Sources/PostgresNIO/New/PSQLError.swift

@@ -393,7 +393,7 @@ public struct PSQLError: Error {
 
 /// An error that may happen when a ``PostgresRow`` or ``PostgresCell`` is decoded to native Swift types.
 public struct PostgresDecodingError: Error, Equatable {
-    public struct Code: Hashable, Error {
+    public struct Code: Hashable, Error, CustomStringConvertible {
         enum Base {
             case missingData
             case typeMismatch
@@ -409,6 +409,17 @@ public struct PostgresDecodingError: Error, Equatable {
         public static let missingData = Self.init(.missingData)
         public static let typeMismatch = Self.init(.typeMismatch)
         public static let failure = Self.init(.failure)
+        
+        public var description: String {
+            switch self.base {
+            case .missingData:
+                return "missingData"
+            case .typeMismatch:
+                return "typeMismatch"
+            case .failure:
+                return "failure"
+            }
+        }
     }
 
     /// The decoding error code
@@ -476,3 +487,24 @@ extension PostgresDecodingError: CustomStringConvertible {
         "Database error"
     }
 }
+
+extension PostgresDecodingError: CustomDebugStringConvertible {
+    public var debugDescription: String {
+        var result = #"PostgresDecodingError(code: \#(self.code)"#
+        
+        result.append(#", columnName: \#(String(reflecting: self.columnName))"#)
+        result.append(#", columnIndex: \#(self.columnIndex)"#)
+        result.append(#", targetType: \#(String(reflecting: self.targetType))"#)
+        result.append(#", postgresType: \#(self.postgresType)"#)
+        result.append(#", postgresFormat: \#(self.postgresFormat)"#)
+        if let postgresData = self.postgresData {
+            result.append(#", postgresData: \#(postgresData.debugDescription)"#) // https://github.com/apple/swift-nio/pull/2418
+        }
+        result.append(#", file: \#(self.file)"#)
+        result.append(#", line: \#(self.line)"#)
+        result.append(")")
+
+        return result
+    }
+}
+

Tests/PostgresNIOTests/New/PostgresErrorTests.swift

@@ -34,7 +34,7 @@ final class PostgresDecodingErrorTests: XCTestCase {
     }
 
     func testPostgresDecodingErrorDescription() {
-        let error = PostgresDecodingError(
+        let error1 = PostgresDecodingError(
             code: .typeMismatch,
             columnName: "column",
             columnIndex: 0,
@@ -46,6 +46,39 @@ final class PostgresDecodingErrorTests: XCTestCase {
             line: 123
         )
 
-        XCTAssertEqual("\(error)", "Database error")
+        let error2 = PostgresDecodingError(
+            code: .missingData,
+            columnName: "column",
+            columnIndex: 0,
+            targetType: [[String: String]].self,
+            postgresType: .jsonbArray,
+            postgresFormat: .binary,
+            postgresData: nil,
+            file: "bar.swift",
+            line: 123
+        )
+
+        // Plain description
+        XCTAssertEqual(String(describing: error1), "Database error")
+        XCTAssertEqual(String(describing: error2), "Database error")
+        
+        // Extended debugDescription
+        XCTAssertEqual(String(reflecting: error1), """
+            PostgresDecodingError(code: typeMismatch,\
+             columnName: "column", columnIndex: 0,\
+             targetType: Swift.String,\
+             postgresType: TEXT, postgresFormat: binary,\
+             postgresData: \(error1.postgresData?.debugDescription ?? "nil"),\
+             file: foo.swift, line: 123\
+            )
+            """)
+        XCTAssertEqual(String(reflecting: error2), """
+            PostgresDecodingError(code: missingData,\
+             columnName: "column", columnIndex: 0,\
+             targetType: Swift.Array<Swift.Dictionary<Swift.String, Swift.String>>,\
+             postgresType: JSONB[], postgresFormat: binary,\
+             file: bar.swift, line: 123\
+            )
+            """)
     }
 }