From 0772ffb6ed3f7ba1fb1b853f93876b2fa5c9fef2 Mon Sep 17 00:00:00 2001
From: Stefan Thomas <justmoon@members.fsf.org>
Date: Sun, 9 Feb 2014 23:05:30 -0800
Subject: [PATCH] Currency: Behavior change for to_json for demurrage
 currencies.

Currency#to_json should output a format that can be successfully converted back
to a Currency object via from_json. So for demurrage currencies it should output
the full hex currency code.

Currency#to_human on the other hand should always print something a human will
understand. For demurrage currencies we'll print the three-letter code for now.
---
 src/js/ripple/currency.js | 11 +++++++++--
 test/currency-test.js     | 17 +++++++++++++++--
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/src/js/ripple/currency.js b/src/js/ripple/currency.js
index 12e05a84..566be643 100644
--- a/src/js/ripple/currency.js
+++ b/src/js/ripple/currency.js
@@ -193,11 +193,13 @@ Currency.prototype.get_interest_at = function (referenceDate) {
 
 Currency.prototype.to_json = function () {
   if (!this.is_valid()) {
-    // XXX This backwards compatible behavior, but probably not very good.
+    // XXX This is backwards compatible behavior, but probably not very good.
     return "XRP";
   }
 
-  if (/^[A-Z0-9]{3}$/.test(this._iso_code)) {
+  // Any currency with standard properties and a valid code can be abbreviated
+  // in the JSON wire format as the three character code.
+  if (/^[A-Z0-9]{3}$/.test(this._iso_code) && !this.has_interest()) {
     return this._iso_code;
   }
 
@@ -215,6 +217,11 @@ Currency.prototype.to_json = function () {
 };
 
 Currency.prototype.to_human = function () {
+  // to_human() will always print the human-readable currency code if available.
+  if (/^[A-Z0-9]{3}$/.test(this._iso_code)) {
+    return this._iso_code;
+  }
+
   return this.to_json();
 };
 
diff --git a/test/currency-test.js b/test/currency-test.js
index 65a83168..ee2d5e54 100644
--- a/test/currency-test.js
+++ b/test/currency-test.js
@@ -10,8 +10,9 @@ describe('Currency', function() {
     it('json_rewrite("NaN") == "XRP"', function() {
       assert.strictEqual('XRP', currency.json_rewrite(NaN));
     });
-    it('json_rewrite("015841551A748AD2C1F76FF6ECB0CCCD00000000") == "XAU"', function() {
-      assert.strictEqual('XAU', currency.json_rewrite("015841551A748AD2C1F76FF6ECB0CCCD00000000"));
+    it('json_rewrite("015841551A748AD2C1F76FF6ECB0CCCD00000000") == "015841551A748AD2C1F76FF6ECB0CCCD00000000"', function() {
+      assert.strictEqual(currency.json_rewrite("015841551A748AD2C1F76FF6ECB0CCCD00000000"),
+                         '015841551A748AD2C1F76FF6ECB0CCCD00000000');
     });
   });
   describe('from_json', function() {
@@ -27,6 +28,18 @@ describe('Currency', function() {
       assert.strictEqual('XRP', r.to_json());
     });
   });
+  describe('to_human', function() {
+    it('"USD".to_human() == "USD"', function() {
+      assert.strictEqual('USD', currency.from_json('USD').to_human());
+    });
+    it('"NaN".to_human() == "XRP"', function() {
+      assert.strictEqual('XRP', currency.from_json(NaN).to_human());
+    });
+    it('"015841551A748AD2C1F76FF6ECB0CCCD00000000") == "015841551A748AD2C1F76FF6ECB0CCCD00000000"', function() {
+      assert.strictEqual(currency.from_json("015841551A748AD2C1F76FF6ECB0CCCD00000000").to_human(),
+                         'XAU');
+    });
+  });
   describe('parse_json(currency obj)', function() {
     assert.strictEqual('USD', new currency().parse_json(currency.from_json('USD')).to_json());
   });