Fix bulkString bug

Author: Mordil

Sources/NIORedis/Coders/RedisDataDecoder.swift

@@ -128,23 +128,22 @@ extension RedisDataDecoder {
         // Redis sends '-1' to represent a null string
         guard size > -1 else { return .parsed(.null) }
 
-        // Redis can hold empty bulk strings, and represents it with a 0 size
-        // so return an empty string
+        // verify that we have our expected bulk string message
+        // by adding the expected CRLF bytes to the parsed size
+        // even if the size is 0, Redis provides line endings (i.e. $0\r\n\r\n)
+        let readableByteCount = buffer.readableBytes - position
+        let expectedRemainingMessageSize = size + 2
+        guard readableByteCount >= expectedRemainingMessageSize else { return .notYetParsed }
+
         guard size > 0 else {
             // Move the tip of the message position
-            // since size = 0, and we successfully parsed the size
-            // the beginning of the next message should be 2 further (the final \r\n - $0\r\n\r\n)
             position += 2
             return .parsed(.bulkString(Data()))
         }
 
-        // verify that we have at least our expected bulk string message
-        // by adding the expected CRLF bytes to the parsed size
-        let readableByteCount = buffer.readableBytes - position
-        let expectedRemainingMessageSize = size + 2
-        guard readableByteCount >= expectedRemainingMessageSize else { return .notYetParsed }
-
-        guard let bytes = buffer.copyBytes(at: position, length: expectedRemainingMessageSize) else { return .notYetParsed }
+        guard let bytes = buffer.copyBytes(at: position, length: expectedRemainingMessageSize) else {
+            return .notYetParsed
+        }
 
         // Move the tip of the message position for recursive parsing to just after the newline
         // of the bulk string content

Tests/NIORedisTests/RedisDataDecoder+ParsingTests.swift renamed to Tests/NIORedisTests/Data/RedisDataDecoder+ParsingTests.swift

@@ -255,13 +255,13 @@ extension RedisDataDecoderParsingTests {
 
 extension RedisDataDecoderParsingTests {
     func testParsing_bulkString_handlesMissingEndings() throws {
-        for message in ["$6", "$6\r\n", "$6\r\nabcdef"]  {
+        for message in ["$6", "$6\r\n", "$6\r\nabcdef", "$0\r\n"]  {
             XCTAssertNil(parseTestBulkString(message))
         }
     }
 
     func testParsing_bulkString_withNoSize_returnsEmpty() throws {
-        let result = parseTestBulkString("$0\r\n")
+        let result = parseTestBulkString("$0\r\n\r\n")
         XCTAssertEqual(result?.data?.count, 0)
     }