allow bufs in constructors

For Transaction, Block and Blockheader. This is a convenience so if you happen
to have the buffer for one of these, you can make a new one like this:

Transaction(txbuf);

Rather than having to do this:

Transaction().fromBuffer(txbuf);

lib/block.js

@@ -16,6 +16,9 @@ var Block = function Block(magicnum, blocksize, blockheader, txsvi, txs) {
       txsvi: txsvi,
       txs: txs
     });
+  } else if (Buffer.isBuffer(magicnum)) {
+    var blockbuf = magicnum;
+    this.fromBuffer(blockbuf);
   } else if (magicnum) {
     var obj = magicnum;
   }

lib/blockheader.js

@@ -13,6 +13,9 @@ var Blockheader = function Blockheader(version, prevblockidbuf, merklerootbuf, t
       bits: bits,
       nonce: nonce
     });
+  } else if (Buffer.isBuffer(version)) {
+    var bhbuf = version;
+    this.fromBuffer(bhbuf);
   } else if (version) {
     var obj = version;
     this.set(obj);

lib/transaction.js

@@ -17,6 +17,9 @@ var Transaction = function Transaction(version, txinsvi, txins, txoutsvi, txouts
       txouts: txouts,
       nlocktime: nlocktime
     });
+  } else if (Buffer.isBuffer(version)) {
+    var txbuf = version;
+    this.fromBuffer(txbuf);
   } else if (version) {
     var obj = version;
     this.set(obj);

lib/txin.js

@@ -7,6 +7,8 @@ var Txin = function Txin(txidbuf, txoutnum, scriptvi, script, seqnum) {
   if (!(this instanceof Txin))
     return new Txin(txidbuf, txoutnum, scriptvi, script, seqnum);
   if (Buffer.isBuffer(txidbuf)) {
+    if (txidbuf.length !== 32)
+      throw new Error('txidbuf must be 32 bytes');
     this.txidbuf = txidbuf;
     this.txoutnum = txoutnum;
     this.scriptvi = scriptvi;

test/block.js

@@ -8,13 +8,6 @@ var Transaction = require('../lib/transaction');
 
 describe('Block', function() {
   
-  it('should make a new block', function() {
-    var block = new Block();
-    should.exist(block);
-    block = Block();
-    should.exist(block);
-  });
-
   var txidhex = '8c9aa966d35bfeaf031409e0001b90ccdafd8d859799eb945a3c515b8260bcf2';
   var txhex = '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';
   var txbuf = new Buffer(txhex, 'hex');
@@ -40,6 +33,15 @@ describe('Block', function() {
   var genesisbuf = new Buffer(genesishex, 'hex');
   var genesisidhex = '000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f';
 
+  it('should make a new block', function() {
+    var block = new Block();
+    should.exist(block);
+    block = Block();
+    should.exist(block);
+    block = Block(blockbuf);
+    block.toBuffer().toString('hex').should.equal(blockhex);
+  });
+
   describe('#set', function() {
 
     it('should set these known values', function() {

test/blockheader.js

@@ -5,13 +5,6 @@ var should = require('chai').should();
 
 describe('Blockheader', function() {
   
-  it('should make a new blockheader', function() {
-    var blockheader = new Blockheader();
-    should.exist(blockheader);
-    blockheader = Blockheader();
-    should.exist(blockheader);
-  });
-
   var bh = new Blockheader();
   var version = 1;
   var prevblockidbuf = new Buffer(32);
@@ -32,6 +25,14 @@ describe('Blockheader', function() {
   bhhex = '0100000005050505050505050505050505050505050505050505050505050505050505050909090909090909090909090909090909090909090909090909090909090909020000000300000004000000';
   bhbuf = new Buffer(bhhex, 'hex');
 
+  it('should make a new blockheader', function() {
+    var blockheader = new Blockheader();
+    should.exist(blockheader);
+    blockheader = Blockheader();
+    should.exist(blockheader);
+    Blockheader(bhbuf).toBuffer().toString('hex').should.equal(bhhex);
+  });
+
   describe('#set', function() {
 
     it('should set all the variables', function() {

test/transaction.js

@@ -8,13 +8,6 @@ var BufferWriter = require('../lib/bufferwriter');
 
 describe('Transaction', function() {
 
-  it('should make a new transaction', function() {
-    var tx = new Transaction();
-    should.exist(tx);
-    tx = Transaction();
-    should.exist(tx);
-  });
-
   var txin = Txin().fromBuffer(new Buffer('00000000000000000000000000000000000000000000000000000000000000000000000001ae00000000', 'hex'));
   var txout = Txout().fromBuffer(new Buffer('050000000000000001ae', 'hex'));
   var tx = Transaction().set({
@@ -32,6 +25,14 @@ describe('Transaction', function() {
   var tx2hex = '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';
   var tx2buf = new Buffer(tx2hex, 'hex');
 
+  it('should make a new transaction', function() {
+    var tx = new Transaction();
+    should.exist(tx);
+    tx = Transaction();
+    should.exist(tx);
+    Transaction(txbuf).toBuffer().toString('hex').should.equal(txhex);
+  });
+
   describe('#set', function() {
 
     it('should set all the basic parameters', function() {

test/txin.js

@@ -6,13 +6,6 @@ var BufferReader = require('../lib/bufferreader');
 
 describe('Txin', function() {
   
-  it('should make a new txin', function() {
-    var txin = new Txin();
-    should.exist(txin);
-    txin = Txin();
-    should.exist(txin);
-  });
-
   var txidbuf = new Buffer(32);
   txidbuf.fill(0);
   var txoutnum = 0;
@@ -27,6 +20,21 @@ describe('Txin', function() {
     seqnum: seqnum
   });
 
+  it('should make a new txin', function() {
+    var txin = new Txin();
+    should.exist(txin);
+    txin = Txin();
+    should.exist(txin);
+    var txidbuf = new Buffer(32);
+    txidbuf.fill(0);
+    Txin(txidbuf).txidbuf.length.should.equal(32);
+    (function() {
+      var txidbuf2 = new Buffer(33);
+      txidbuf2.fill(0);
+      Txin(txidbuf2);
+    }).should.throw('txidbuf must be 32 bytes');
+  });
+
   describe('#set', function() {
     
     it('should set these vars', function() {

test/txout.js

@@ -8,13 +8,6 @@ var BufferWriter = require('../lib/bufferwriter');
 
 describe('Txout', function() {
   
-  it('should make a new txout', function() {
-    var txout = new Txout();
-    should.exist(txout);
-    txout = Txout();
-    should.exist(txout);
-  });
-
   var valuebn = BN(5);
   var script = Script().fromString("OP_CHECKMULTISIG");
   var scriptvi = Varint(script.toBuffer().length);
@@ -24,6 +17,14 @@ describe('Txout', function() {
     script: script
   });
 
+  it('should make a new txout', function() {
+    var txout = new Txout();
+    should.exist(txout);
+    txout = Txout();
+    should.exist(txout);
+    Txout(valuebn, scriptvi, script).valuebn.toString().should.equal('5');
+  });
+
   describe('#set', function() {
     
     it('should set this object', function() {