Add negative tests for updated read/writeElement.

This commit adds tests for the error paths in the updated readElement and
writeElement functions.

This brings the test coverage back up to 100%.

common_test.go

@@ -147,6 +147,73 @@ func TestElementWire(t *testing.T) {
 	}
 }
 
+// TestElementWireErrors performs negative tests against wire encode and decode
+// of various element types to confirm error paths work correctly.
+func TestElementWireErrors(t *testing.T) {
+	tests := []struct {
+		in       interface{} // Value to encode
+		max      int         // Max size of fixed buffer to induce errors
+		writeErr error       // Expected write error
+		readErr  error       // Expected read error
+	}{
+		{int32(1), 0, io.ErrShortWrite, io.EOF},
+		{uint32(256), 0, io.ErrShortWrite, io.EOF},
+		{int64(65536), 0, io.ErrShortWrite, io.EOF},
+		{[4]byte{0x01, 0x02, 0x03, 0x04}, 0, io.ErrShortWrite, io.EOF},
+		{
+			[btcwire.CommandSize]byte{
+				0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
+				0x09, 0x0a, 0x0b, 0x0c,
+			},
+			0, io.ErrShortWrite, io.EOF,
+		},
+		{
+			[16]byte{
+				0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
+				0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10,
+			},
+			0, io.ErrShortWrite, io.EOF,
+		},
+		{
+			(*btcwire.ShaHash)(&[btcwire.HashSize]byte{ // Make go vet happy.
+				0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
+				0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10,
+				0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18,
+				0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20,
+			}),
+			0, io.ErrShortWrite, io.EOF,
+		},
+		{btcwire.ServiceFlag(btcwire.SFNodeNetwork), 0, io.ErrShortWrite, io.EOF},
+		{btcwire.InvType(btcwire.InvTypeTx), 0, io.ErrShortWrite, io.EOF},
+		{btcwire.BitcoinNet(btcwire.MainNet), 0, io.ErrShortWrite, io.EOF},
+	}
+
+	t.Logf("Running %d tests", len(tests))
+	for i, test := range tests {
+		// Encode to wire format.
+		w := newFixedWriter(test.max)
+		err := btcwire.TstWriteElement(w, test.in)
+		if err != test.writeErr {
+			t.Errorf("writeElement #%d wrong error got: %v, want: %v",
+				i, err, test.writeErr)
+			continue
+		}
+
+		// Decode from wire format.
+		r := newFixedReader(test.max, nil)
+		val := test.in
+		if reflect.ValueOf(test.in).Kind() != reflect.Ptr {
+			val = reflect.New(reflect.TypeOf(test.in)).Interface()
+		}
+		err = btcwire.TstReadElement(r, val)
+		if err != test.readErr {
+			t.Errorf("readElement #%d wrong error got: %v, want: %v",
+				i, err, test.readErr)
+			continue
+		}
+	}
+}
+
 // TestVarIntWire tests wire encode and decode for variable length integers.
 func TestVarIntWire(t *testing.T) {
 	pver := btcwire.ProtocolVersion

test_coverage.txt

@@ -1,28 +1,30 @@
 
+github.com/conformal/btcwire/common.go		 writeElement				 100.00% (61/61)
+github.com/conformal/btcwire/common.go		 readElement				 100.00% (61/61)
 github.com/conformal/btcwire/message.go		 ReadMessage				 100.00% (37/37)
 github.com/conformal/btcwire/msgtx.go		 MsgTx.BtcDecode			 100.00% (36/36)
 github.com/conformal/btcwire/message.go		 WriteMessage				 100.00% (31/31)
 github.com/conformal/btcwire/msgtx.go		 MsgTx.BtcEncode			 100.00% (26/26)
 github.com/conformal/btcwire/msgversion.go	 MsgVersion.BtcDecode			 100.00% (25/25)
 github.com/conformal/btcwire/msgtx.go		 MsgTx.Copy				 100.00% (24/24)
-github.com/conformal/btcwire/msgtx.go		 readTxIn				 100.00% (22/22)
 github.com/conformal/btcwire/msgversion.go	 MsgVersion.BtcEncode			 100.00% (22/22)
+github.com/conformal/btcwire/msgtx.go		 readTxIn				 100.00% (22/22)
 github.com/conformal/btcwire/common.go		 readVarInt				 100.00% (21/21)
-github.com/conformal/btcwire/netaddress.go	 readNetAddress				 100.00% (20/20)
-github.com/conformal/btcwire/common.go		 writeVarInt				 100.00% (20/20)
-github.com/conformal/btcwire/msggetheaders.go	 MsgGetHeaders.BtcDecode		 100.00% (20/20)
 github.com/conformal/btcwire/message.go		 makeEmptyMessage			 100.00% (20/20)
 github.com/conformal/btcwire/msggetblocks.go	 MsgGetBlocks.BtcDecode			 100.00% (20/20)
+github.com/conformal/btcwire/common.go		 writeVarInt				 100.00% (20/20)
+github.com/conformal/btcwire/msggetheaders.go	 MsgGetHeaders.BtcDecode		 100.00% (20/20)
+github.com/conformal/btcwire/netaddress.go	 readNetAddress				 100.00% (20/20)
 github.com/conformal/btcwire/msgblock.go	 MsgBlock.DeserializeTxLoc		 100.00% (19/19)
-github.com/conformal/btcwire/msggetheaders.go	 MsgGetHeaders.BtcEncode		 100.00% (18/18)
 github.com/conformal/btcwire/msggetblocks.go	 MsgGetBlocks.BtcEncode			 100.00% (18/18)
-github.com/conformal/btcwire/msgheaders.go	 MsgHeaders.BtcDecode			 100.00% (17/17)
+github.com/conformal/btcwire/msggetheaders.go	 MsgGetHeaders.BtcEncode		 100.00% (18/18)
 github.com/conformal/btcwire/msgtx.go		 readTxOut				 100.00% (17/17)
+github.com/conformal/btcwire/msgheaders.go	 MsgHeaders.BtcDecode			 100.00% (17/17)
 github.com/conformal/btcwire/msgtx.go		 writeTxIn				 100.00% (16/16)
-github.com/conformal/btcwire/msgaddr.go		 MsgAddr.BtcEncode			 100.00% (15/15)
-github.com/conformal/btcwire/msgblock.go	 MsgBlock.BtcDecode			 100.00% (15/15)
 github.com/conformal/btcwire/shahash.go		 NewShaHashFromStr			 100.00% (15/15)
+github.com/conformal/btcwire/msgblock.go	 MsgBlock.BtcDecode			 100.00% (15/15)
 github.com/conformal/btcwire/msgheaders.go	 MsgHeaders.BtcEncode			 100.00% (15/15)
+github.com/conformal/btcwire/msgaddr.go		 MsgAddr.BtcEncode			 100.00% (15/15)
 github.com/conformal/btcwire/msggetdata.go	 MsgGetData.BtcDecode			 100.00% (14/14)
 github.com/conformal/btcwire/netaddress.go	 writeNetAddress			 100.00% (14/14)
 github.com/conformal/btcwire/msgnotfound.go	 MsgNotFound.BtcDecode			 100.00% (14/14)
@@ -31,62 +33,62 @@ github.com/conformal/btcwire/msgaddr.go		 MsgAddr.BtcDecode			 100.00% (14/14)
 github.com/conformal/btcwire/msgtx.go		 writeTxOut				 100.00% (13/13)
 github.com/conformal/btcwire/msginv.go		 MsgInv.BtcEncode			 100.00% (12/12)
 github.com/conformal/btcwire/msggetdata.go	 MsgGetData.BtcEncode			 100.00% (12/12)
-github.com/conformal/btcwire/protocol.go	 ServiceFlag.String			 100.00% (12/12)
 github.com/conformal/btcwire/msgnotfound.go	 MsgNotFound.BtcEncode			 100.00% (12/12)
+github.com/conformal/btcwire/protocol.go	 ServiceFlag.String			 100.00% (12/12)
 github.com/conformal/btcwire/common.go		 readVarString				 100.00% (11/11)
-github.com/conformal/btcwire/blockheader.go	 readBlockHeader			 100.00% (10/10)
 github.com/conformal/btcwire/message.go		 discardInput				 100.00% (10/10)
+github.com/conformal/btcwire/blockheader.go	 readBlockHeader			 100.00% (10/10)
+github.com/conformal/btcwire/msgtx.go		 writeOutPoint				 100.00% (9/9)
 github.com/conformal/btcwire/msgblock.go	 MsgBlock.BtcEncode			 100.00% (9/9)
 github.com/conformal/btcwire/msgtx.go		 readOutPoint				 100.00% (9/9)
-github.com/conformal/btcwire/msgtx.go		 writeOutPoint				 100.00% (9/9)
 github.com/conformal/btcwire/msgalert.go	 MsgAlert.BtcDecode			 100.00% (8/8)
-github.com/conformal/btcwire/blockheader.go	 writeBlockHeader			 100.00% (8/8)
 github.com/conformal/btcwire/msgalert.go	 MsgAlert.BtcEncode			 100.00% (8/8)
+github.com/conformal/btcwire/blockheader.go	 writeBlockHeader			 100.00% (8/8)
 github.com/conformal/btcwire/common.go		 varIntSerializeSize			 100.00% (7/7)
-github.com/conformal/btcwire/msgversion.go	 NewMsgVersionFromConn			 100.00% (7/7)
-github.com/conformal/btcwire/msgpong.go		 MsgPong.BtcEncode			 100.00% (7/7)
-github.com/conformal/btcwire/msgpong.go		 MsgPong.BtcDecode			 100.00% (7/7)
-github.com/conformal/btcwire/message.go		 readMessageHeader			 100.00% (7/7)
 github.com/conformal/btcwire/common.go		 writeVarString				 100.00% (7/7)
 github.com/conformal/btcwire/common.go		 randomUint64				 100.00% (7/7)
-github.com/conformal/btcwire/msgtx.go		 MsgTx.SerializeSize			 100.00% (6/6)
+github.com/conformal/btcwire/msgpong.go		 MsgPong.BtcEncode			 100.00% (7/7)
+github.com/conformal/btcwire/msgversion.go	 NewMsgVersionFromConn			 100.00% (7/7)
+github.com/conformal/btcwire/msgpong.go		 MsgPong.BtcDecode			 100.00% (7/7)
+github.com/conformal/btcwire/message.go		 readMessageHeader			 100.00% (7/7)
 github.com/conformal/btcwire/common.go		 DoubleSha256				 100.00% (6/6)
-github.com/conformal/btcwire/msgping.go		 MsgPing.BtcEncode			 100.00% (5/5)
+github.com/conformal/btcwire/msgtx.go		 MsgTx.SerializeSize			 100.00% (6/6)
-github.com/conformal/btcwire/shahash.go		 ShaHash.SetBytes			 100.00% (5/5)
-github.com/conformal/btcwire/msgnotfound.go	 MsgNotFound.AddInvVect			 100.00% (5/5)
-github.com/conformal/btcwire/common.go		 writeElements				 100.00% (5/5)
-github.com/conformal/btcwire/msgblock.go	 MsgBlock.TxShas			 100.00% (5/5)
-github.com/conformal/btcwire/msgtx.go		 MsgTx.TxSha				 100.00% (5/5)
-github.com/conformal/btcwire/blockheader.go	 BlockHeader.BlockSha			 100.00% (5/5)
-github.com/conformal/btcwire/msggetblocks.go	 MsgGetBlocks.AddBlockLocatorHash	 100.00% (5/5)
 github.com/conformal/btcwire/msgping.go		 MsgPing.BtcDecode			 100.00% (5/5)
+github.com/conformal/btcwire/msggetblocks.go	 MsgGetBlocks.AddBlockLocatorHash	 100.00% (5/5)
+github.com/conformal/btcwire/blockheader.go	 BlockHeader.BlockSha			 100.00% (5/5)
 github.com/conformal/btcwire/msggetdata.go	 MsgGetData.AddInvVect			 100.00% (5/5)
 github.com/conformal/btcwire/netaddress.go	 NewNetAddress				 100.00% (5/5)
+github.com/conformal/btcwire/msgtx.go		 MsgTx.TxSha				 100.00% (5/5)
+github.com/conformal/btcwire/shahash.go		 ShaHash.SetBytes			 100.00% (5/5)
+github.com/conformal/btcwire/msgblock.go	 MsgBlock.TxShas			 100.00% (5/5)
+github.com/conformal/btcwire/shahash.go		 NewShaHash				 100.00% (5/5)
 github.com/conformal/btcwire/msggetheaders.go	 MsgGetHeaders.AddBlockLocatorHash	 100.00% (5/5)
 github.com/conformal/btcwire/msgaddr.go		 MsgAddr.AddAddress			 100.00% (5/5)
 github.com/conformal/btcwire/msgaddr.go		 MsgAddr.AddAddresses			 100.00% (5/5)
 github.com/conformal/btcwire/msgheaders.go	 MsgHeaders.AddBlockHeader		 100.00% (5/5)
-github.com/conformal/btcwire/shahash.go		 NewShaHash				 100.00% (5/5)
+github.com/conformal/btcwire/msgping.go		 MsgPing.BtcEncode			 100.00% (5/5)
 github.com/conformal/btcwire/msginv.go		 MsgInv.AddInvVect			 100.00% (5/5)
+github.com/conformal/btcwire/common.go		 writeElements				 100.00% (5/5)
+github.com/conformal/btcwire/msgnotfound.go	 MsgNotFound.AddInvVect			 100.00% (5/5)
 github.com/conformal/btcwire/common.go		 readElements				 100.00% (5/5)
+github.com/conformal/btcwire/msgpong.go		 MsgPong.MaxPayloadLength		 100.00% (4/4)
 github.com/conformal/btcwire/msgmempool.go	 MsgMemPool.BtcDecode			 100.00% (4/4)
 github.com/conformal/btcwire/msgmempool.go	 MsgMemPool.BtcEncode			 100.00% (4/4)
-github.com/conformal/btcwire/msgpong.go		 MsgPong.MaxPayloadLength		 100.00% (4/4)
-github.com/conformal/btcwire/shahash.go		 ShaHash.String				 100.00% (4/4)
 github.com/conformal/btcwire/netaddress.go	 maxNetAddressPayload			 100.00% (4/4)
-github.com/conformal/btcwire/invvect.go		 writeInvVect				 100.00% (4/4)
+github.com/conformal/btcwire/shahash.go		 ShaHash.String				 100.00% (4/4)
 github.com/conformal/btcwire/invvect.go		 readInvVect				 100.00% (4/4)
 github.com/conformal/btcwire/msgping.go		 MsgPing.MaxPayloadLength		 100.00% (4/4)
-github.com/conformal/btcwire/msgversion.go	 MsgVersion.HasService			 100.00% (3/3)
+github.com/conformal/btcwire/invvect.go		 writeInvVect				 100.00% (4/4)
-github.com/conformal/btcwire/msgblock.go	 MsgBlock.AddTransaction		 100.00% (3/3)
+github.com/conformal/btcwire/msgaddr.go		 MsgAddr.MaxPayloadLength		 100.00% (3/3)
-github.com/conformal/btcwire/invvect.go		 InvType.String				 100.00% (3/3)
 github.com/conformal/btcwire/error.go		 MessageError.Error			 100.00% (3/3)
 github.com/conformal/btcwire/shahash.go		 ShaHash.Bytes				 100.00% (3/3)
+github.com/conformal/btcwire/msgblock.go	 MsgBlock.AddTransaction		 100.00% (3/3)
+github.com/conformal/btcwire/msgversion.go	 MsgVersion.HasService			 100.00% (3/3)
+github.com/conformal/btcwire/invvect.go		 InvType.String				 100.00% (3/3)
 github.com/conformal/btcwire/netaddress.go	 NetAddress.HasService			 100.00% (3/3)
-github.com/conformal/btcwire/msgaddr.go		 MsgAddr.MaxPayloadLength		 100.00% (3/3)
-github.com/conformal/btcwire/netaddress.go	 NetAddress.SetAddress			 100.00% (2/2)
-github.com/conformal/btcwire/netaddress.go	 NewNetAddressIPPort			 100.00% (2/2)
 github.com/conformal/btcwire/msgblock.go	 MsgBlock.ClearTransactions		 100.00% (2/2)
+github.com/conformal/btcwire/netaddress.go	 NewNetAddressIPPort			 100.00% (2/2)
+github.com/conformal/btcwire/netaddress.go	 NetAddress.SetAddress			 100.00% (2/2)
 github.com/conformal/btcwire/msggetblocks.go	 MsgGetBlocks.Command			 100.00% (1/1)
 github.com/conformal/btcwire/blockheader.go	 NewBlockHeader				 100.00% (1/1)
 github.com/conformal/btcwire/common.go		 RandomUint64				 100.00% (1/1)
@@ -156,7 +158,5 @@ github.com/conformal/btcwire/msgversion.go	 NewMsgVersion				 100.00% (1/1)
 github.com/conformal/btcwire/netaddress.go	 NetAddress.AddService			 100.00% (1/1)
 github.com/conformal/btcwire/shahash.go		 ShaHash.IsEqual			 100.00% (1/1)
 github.com/conformal/btcwire/invvect.go		 NewInvVect				 100.00% (1/1)
-github.com/conformal/btcwire/common.go		 writeElement				 96.77% (60/62)
+github.com/conformal/btcwire			 ---------------------------------	 100.00% (1123/1123)
-github.com/conformal/btcwire/common.go		 readElement				 96.72% (59/61)
-github.com/conformal/btcwire			 ---------------------------------	 99.64% (1120/1124)