finace: ensure supplyDefaults is idempotent

Author: etpinard

src/traces/candlestick/defaults.js

@@ -15,14 +15,12 @@ var helpers = require('../ohlc/helpers');
 var attributes = require('./attributes');
 
 module.exports = function supplyDefaults(traceIn, traceOut) {
+    helpers.pushDummyTransformOpts(traceIn, traceOut);
 
     function coerce(attr, dflt) {
         return Lib.coerce(traceIn, traceOut, attributes, attr, dflt);
     }
 
-    var transformOpts = { type: 'candlestick' };
-    helpers.prependTransformOpts(traceIn, traceOut, transformOpts);
-
     var len = handleOHLC(traceIn, traceOut, coerce);
     if(len === 0) {
         traceOut.visible = false;

src/traces/ohlc/defaults.js

@@ -15,14 +15,12 @@ var attributes = require('./attributes');
 var helpers = require('./helpers');
 
 module.exports = function supplyDefaults(traceIn, traceOut) {
+    helpers.pushDummyTransformOpts(traceIn, traceOut);
 
     function coerce(attr, dflt) {
         return Lib.coerce(traceIn, traceOut, attributes, attr, dflt);
     }
 
-    var transformOpts = { type: 'ohlc' };
-    helpers.prependTransformOpts(traceIn, traceOut, transformOpts);
-
     var len = handleOHLC(traceIn, traceOut, coerce);
     if(len === 0) {
         traceOut.visible = false;

src/traces/ohlc/helpers.js

@@ -12,8 +12,23 @@
 var Lib = require('../../lib');
 
 // TODO add comment
-exports.prependTransformOpts = function(traceIn, traceOut, transformOpts) {
+exports.pushDummyTransformOpts = function(traceIn, traceOut) {
+    var transformOpts = {
+
+        // give dummy transform the same type as trace
+        type: traceOut.type,
+
+        // track ephemeral transforms in user data
+        _ephemeral: true
+    };
+
     if(Array.isArray(traceIn.transforms)) {
+        var transformsIn = traceIn.transforms;
+
+        for(var i = 0; i < transformsIn.length; i++) {
+            if(transformsIn[i]._ephemeral) transformsIn.splice(i, 1);
+        }
+
         traceIn.transforms.push(transformOpts);
     }
     else {

test/jasmine/tests/finance_test.js

@@ -54,6 +54,26 @@ describe('finance charts defaults:', function() {
         expect(directions).toEqual(['increasing', 'decreasing', 'increasing', 'decreasing']);
     });
 
+    it('unfortunately mutates user trace', function() {
+        var trace0 = Lib.extendDeep({}, mock0, {
+            type: 'ohlc'
+        });
+
+        var trace1 = Lib.extendDeep({}, mock1, {
+            type: 'candlestick'
+        });
+
+        var out = _supply([trace0, trace1]);
+        expect(out.data[0].transforms).toEqual([{ type: 'ohlc', _ephemeral: true }]);
+        expect(out.data[1].transforms).toEqual([{ type: 'candlestick', _ephemeral: true }]);
+
+        // but at least in an idempotent way
+
+        var out2 = _supply(out.data);
+        expect(out2.data[0].transforms).toEqual([{ type: 'ohlc', _ephemeral: true }]);
+        expect(out2.data[1].transforms).toEqual([{ type: 'candlestick', _ephemeral: true }]);
+    });
+
     it('should work with transforms', function() {
         var trace0 = Lib.extendDeep({}, mock1, {
             type: 'ohlc',