scripts: add dataOutput convenience function

src/scripts.js

@@ -241,9 +241,14 @@ function multisigInput(signatures, scriptPubKey) {
   return Script.fromChunks([].concat(ops.OP_0, signatures))
 }
 
+function dataOutput(data) {
+  return Script.fromChunks([ops.OP_RETURN, data])
+}
+
 module.exports = {
   classifyInput: classifyInput,
   classifyOutput: classifyOutput,
+  dataOutput: dataOutput,
   multisigInput: multisigInput,
   multisigOutput: multisigOutput,
   pubKeyHashInput: pubKeyHashInput,

test/fixtures/scripts.json

@@ -51,7 +51,8 @@
     },
     {
       "type": "nulldata",
-      "scriptPubKey": "OP_RETURN ffffffffffffffffffffffffffffffffffffffff"
+      "data": "deadffffffffffffffffffffffffffffffffbeef",
+      "scriptPubKey": "OP_RETURN deadffffffffffffffffffffffffffffffffbeef"
     }
   ],
   "invalid": {

test/scripts.js

@@ -184,4 +184,19 @@ describe('Scripts', function() {
       })
     })
   })
+
+  describe('data', function() {
+    fixtures.valid.forEach(function(f) {
+      if (f.type !== 'nulldata') return
+
+      var data = new Buffer(f.data, 'hex')
+      var scriptPubKey = scripts.dataOutput(data)
+
+      describe('output script', function() {
+        it('is generated correctly for ' + f.scriptPubKey, function() {
+          assert.equal(scriptPubKey.toASM(), f.scriptPubKey)
+        })
+      })
+    })
+  })
 })