Use writerIndex to figure out the convinience end of useful content i…

…n the buffer

Sources/NIOCore/ByteBuffer-core.swift

@@ -1129,7 +1129,7 @@ extension ByteBuffer {
     ///     - offset:  The offset from the beginning of the buffer, in bytes. Defaults to 0.
     ///     - readableOnly: Whether to only dump the `readableBytes` part (before the `writerIndex`), or to dump the full buffer, including empty bytes in the end of the allocated space. Defaults to true.
     func hexDumpShort(offset: Int = 0, readableOnly: Bool = true) -> String {
-        let length = (readableOnly ? self.readableBytes : self.capacity) - offset
+        let length = (readableOnly ? self.writerIndex : self.capacity) - offset
         return self._storage.dumpBytes(slice: self._storage.fullSlice,
                                        offset: offset,
                                        length: length)

Tests/NIOCoreTests/ByteBufferTest.swift

@@ -1874,7 +1874,24 @@ class ByteBufferTest: XCTestCase {
         XCTAssertEqual("6c 6c 6f", buf.hexDumpShort(offset: 2))
     }
 
-    func testXXDClippedHexDump() {
+    func testHexDumpShortWithReaderIndexOffset() {
+        var buf = ByteBufferAllocator().buffer(string: "Hello")
+        let firstTwo = buf.readBytes(length: 2)!
+        XCTAssertEqual([72, 101], firstTwo)
+        XCTAssertEqual("48 65 6c 6c 6f", buf.hexDumpShort())
+    }
+
+    func testHexDumpShortWithReaderIndexOffsetAndReadableOnlyFalse() {
+        var buf = ByteBufferAllocator().buffer(string: "Hello")
+
+        let firstTwo = buf.readBytes(length: 2)!
+        XCTAssertEqual([72, 101], firstTwo)
+
+        let zeroes = String(repeating: " 00", count: buf.capacity - buf.writerIndex)
+        XCTAssertEqual("48 65 6c 6c 6f" + zeroes, buf.hexDumpShort(readableOnly: false))
+    }
+
+    func testHexDumpShortWithLimit() {
         self.buf.clear()
         for f in UInt8.min...UInt8.max {
             self.buf.writeInteger(f)
@@ -1884,8 +1901,6 @@ class ByteBufferTest: XCTestCase {
         XCTAssertEqual(expected, actual)
     }
 
-
-
     func testHexASCIIDump() {
         let buf = ByteBufferAllocator().buffer(string: "Goodbye, world! It was nice knowing you.\n")
         let expected = """