validate transform module on registration:

- module.transform must be a function
- module.attributes and module.supplyDefaults are
  recommended but optional
- log warning if transform module associated with transform
  type isn't found
- extend traceIn if no supplyDefaults method is found.

Author: etpinard

src/plotly.js

@@ -22,7 +22,7 @@
 require('es6-promise').polyfill();
 
 // lib functions
-exports.Lib = require('./lib');
+var Lib = exports.Lib = require('./lib');
 exports.util = require('./lib/svg_text_utils');
 exports.Queue = require('./lib/queue');
 
@@ -55,7 +55,8 @@ exports.ModeBar = require('./components/modebar');
 exports.register = function register(_modules) {
     if(!_modules) {
         throw new Error('No argument passed to Plotly.register.');
-    } else if(_modules && !Array.isArray(_modules)) {
+    }
+    else if(_modules && !Array.isArray(_modules)) {
         _modules = [_modules];
     }
 
@@ -77,6 +78,22 @@ exports.register = function register(_modules) {
                 break;
 
             case 'transform':
+                if(typeof newModule.name !== 'string') {
+                    throw new Error('Transform module *name* must be a string.');
+                }
+
+                var prefix = 'Transform module ' + newModule.name;
+
+                if(typeof newModule.transform !== 'function') {
+                    throw new Error(prefix + ' is missing a *transform* function.');
+                }
+                if(!Lib.isPlainObject(newModule.attributes)) {
+                    Lib.log(prefix + ' registered without an *attributes* object.');
+                }
+                if(typeof newModule.supplyDefaults !== 'function') {
+                    Lib.log(prefix + ' registered without a *supplyDefaults* function.');
+                }
+
                 Plots.transformsRegistry[newModule.name] = newModule;
 
                 break;

src/plots/plots.js

@@ -758,10 +758,18 @@ function supplyTransformDefaults(traceIn, traceOut, layout) {
     for(var i = 0; i < containerIn.length; i++) {
         var transformIn = containerIn[i],
             type = transformIn.type,
-            _module = transformsRegistry[type];
+            _module = transformsRegistry[type],
+            transformOut;
+
+        if(!_module) Lib.warn('Unrecognized transform type ' + type + '.');
 
-        var transformOut = _module.supplyDefaults(transformIn, traceOut, layout);
-        transformOut.type = type;
+        if(_module && _module.supplyDefaults) {
+            transformOut = _module.supplyDefaults(transformIn, traceOut, layout);
+            transformOut.type = type;
+        }
+        else {
+            transformOut = Lib.extendFlat({}, transformIn);
+        }
 
         containerOut.push(transformOut);
     }
@@ -776,12 +784,14 @@ function applyTransforms(fullTrace, fullData, layout) {
             type = transform.type,
             _module = transformsRegistry[type];
 
-        dataOut = _module.transform(dataOut, {
-            transform: transform,
-            fullTrace: fullTrace,
-            fullData: fullData,
-            layout: layout
-        });
+        if(_module) {
+            dataOut = _module.transform(dataOut, {
+                transform: transform,
+                fullTrace: fullTrace,
+                fullData: fullData,
+                layout: layout
+            });
+        }
     }
 
     return dataOut;

test/jasmine/tests/register_test.js

@@ -9,6 +9,7 @@ describe('the register function', function() {
         this.modulesKeys = Object.keys(Plots.modules);
         this.allTypesKeys = Object.keys(Plots.allTypes);
         this.allCategoriesKeys = Object.keys(Plots.allCategories);
+        this.allTransformsKeys = Object.keys(Plots.transformsRegistry);
     });
 
     afterEach(function() {
@@ -21,6 +22,7 @@ describe('the register function', function() {
         revertObj(Plots.modules, this.modulesKeys);
         revertObj(Plots.allTypes, this.allTypesKeys);
         revertObj(Plots.allCategories, this.allCategoriesKeys);
+        revertObj(Plots.transformsRegistry, this.allTransformsKeys);
     });
 
     it('should throw an error when no argument is given', function() {
@@ -68,4 +70,35 @@ describe('the register function', function() {
             Plotly.register([invalidTrace]);
         }).toThrowError(Error, 'Invalid module was attempted to be registered!');
     });
+
+    it('should throw when if transform module is invalid', function() {
+        var missingTransformName = {
+            moduleType: 'transform'
+        };
+
+        expect(function() {
+            Plotly.register(missingTransformName);
+        }).toThrowError(Error, 'Transform module *name* must be a string.');
+
+        var missingTransformFunc = {
+            moduleType: 'transform',
+            name: 'mah-transform'
+        };
+
+        expect(function() {
+            Plotly.register(missingTransformFunc);
+        }).toThrowError(Error, 'Transform module mah-transform is missing a *transform* function.');
+
+        var transformModule = {
+            moduleType: 'transform',
+            name: 'mah-transform',
+            transform: function() {}
+        };
+
+        expect(function() {
+            Plotly.register(transformModule);
+        }).not.toThrow();
+
+        expect(Plots.transformsRegistry['mah-transform']).toBeDefined();
+    });
 });