Use self as the decoder when decoding a ByteBuffer (#1221)

Motivation:

JSONDecoder settings should be respected but were not.

Modifications:

This allows actually configuring the `JSONDecoder` instead of being stuck with the defaults.

Result:

Settings respected.

Sources/NIOFoundationCompat/Codable+ByteBuffer.swift

@@ -104,6 +104,7 @@ extension JSONDecoder {
     /// - returns: The decoded object.
     public func decode<T: Decodable>(_ type: T.Type, from buffer: ByteBuffer) throws -> T {
         return try buffer.getJSONDecodable(T.self,
+                                           decoder: self,
                                            at: buffer.readerIndex,
                                            length: buffer.readableBytes)! // must work, enough readable bytes
     }

Tests/NIOFoundationCompatTests/Codable+ByteBufferTest+XCTest.swift

@@ -36,6 +36,8 @@ extension CodableByteBufferTest {
                 ("testReadWriteJSONDecodableWorks", testReadWriteJSONDecodableWorks),
                 ("testGetSetJSONDecodableWorks", testGetSetJSONDecodableWorks),
                 ("testFailingReadsDoNotChangeReaderIndex", testFailingReadsDoNotChangeReaderIndex),
+                ("testCustomEncoderIsRespected", testCustomEncoderIsRespected),
+                ("testCustomDecoderIsRespected", testCustomDecoderIsRespected),
            ]
    }
 }

Tests/NIOFoundationCompatTests/Codable+ByteBufferTest.swift

@@ -156,6 +156,38 @@ class CodableByteBufferTest: XCTestCase {
         }
         XCTAssertNoThrow(try self.buffer.readJSONDecodable(StringAndInt.self, length: writtenBytes ?? -1))
     }
+
+    func testCustomEncoderIsRespected() {
+        let expectedDate = Date(timeIntervalSinceReferenceDate: 86400)
+        let strategyExpectation = XCTestExpectation(description: "Custom encoding strategy invoked")
+        let encoder = JSONEncoder()
+        encoder.dateEncodingStrategy = .custom({ date, encoder in
+            var container = encoder.singleValueContainer()
+            try container.encode(date.timeIntervalSinceReferenceDate)
+            strategyExpectation.fulfill()
+        })
+        XCTAssertNoThrow(try encoder.encode(["date": expectedDate], into: &self.buffer))
+        XCTAssertEqual(XCTWaiter().wait(for: [strategyExpectation], timeout: 0.0), .completed)
+    }
+
+    func testCustomDecoderIsRespected() {
+        let expectedDate = Date(timeIntervalSinceReferenceDate: 86400)
+        let strategyExpectation = XCTestExpectation(description: "Custom decoding strategy invoked")
+        let encoder = JSONEncoder()
+        let decoder = JSONDecoder()
+        encoder.dateEncodingStrategy = .custom({ date, encoder in
+            var container = encoder.singleValueContainer()
+            try container.encode(date.timeIntervalSinceReferenceDate)
+        })
+        decoder.dateDecodingStrategy = .custom({ decoder in
+            strategyExpectation.fulfill()
+            let container = try decoder.singleValueContainer()
+            return Date(timeIntervalSinceReferenceDate: try container.decode(Double.self))
+        })
+        XCTAssertNoThrow(try encoder.encode(["date": expectedDate], into: &self.buffer))
+        XCTAssertNoThrow(XCTAssertEqual(["date": expectedDate], try decoder.decode(Dictionary<String, Date>.self, from: self.buffer)))
+        XCTAssertEqual(XCTWaiter().wait(for: [strategyExpectation], timeout: 0.0), .completed)
+    }
 }
 
 struct StringAndInt: Codable, Equatable {