Add binary <--> json encoding integration tests

* Add full json ledger dumps of ledgers 38129 and 40000 to test/fixtures
* Use `Ledger` to calculate account and transaction hashes and verify
  against dumps

test/ledger-test.js

@@ -0,0 +1,39 @@
+var assert           = require('assert');
+var fs               = require('fs');
+
+var utils            = require('./testutils');
+var Ledger = utils.load_module('ledger').Ledger;
+var config = require('./testutils').get_config();
+
+/**
+* @param ledger_index {Number}
+* Expects a corresponding ledger dump in $repo/test/fixtures/ folder
+*/
+create_ledger_test = function (ledger_index) {
+  describe(String(ledger_index), function () {
+
+    var path = __dirname + '/fixtures/ledger-full-'+ledger_index+'.json';
+
+    var ledger_raw   = fs.readFileSync(path),
+        ledger_json  = JSON.parse(ledger_raw),
+        ledger       = Ledger.from_json(ledger_json);
+
+    it('has account_hash of '+ ledger_json.account_hash, function() {
+      assert.equal(ledger_json.account_hash,
+                   ledger.calc_account_hash({sanity_test:true}).to_hex());
+    })
+    it('has transaction_hash of '+ ledger_json.transaction_hash, function() {
+      assert.equal(ledger_json.transaction_hash,
+                   ledger.calc_tx_hash().to_hex());
+    })
+  })
+}
+
+describe('Ledger', function() {
+  // This is the first recorded ledger with a non empty transaction set
+  create_ledger_test(38129);
+  // Because, why not.
+  create_ledger_test(40000);
+});
+
+// vim:sw=2:sts=2:ts=8:et