Allow engines to support multiple extensions

core/lib/pattern_engines.js

@@ -123,12 +123,19 @@ const PatternEngines = Object.create({
     const of = require('./object_factory');
     if (pattern instanceof of.Pattern && typeof pattern.fileExtension === 'string' && pattern.fileExtension) {
       //loop through known engines and find the one that supports the pattern's fileExtension
-      //TODO: support multiple extensions someday, such as .handlebars and .hbs
       const engineNames = Object.keys(this);
       for (let i = 0; i < engineNames.length; i++) {
         const engine = this[engineNames[i]];
-        if (engine.engineFileExtension === pattern.fileExtension) {
-          return engine.engineName;
+
+        if (Array.isArray(engine.engineFileExtension)) {
+          if (engine.engineFileExtension.includes(pattern.fileExtension)) {
+            return engine.engineName;
+          }
+        } else {
+          //this likely means the users engines are out of date. todo: tell them to upgrade
+          if (engine.engineFileExtension === pattern.fileExtension) {
+            return engine.engineName;
+          }
         }
       }
     }
@@ -147,11 +154,13 @@ const PatternEngines = Object.create({
     }
   },
 
+  // combine all found engines into a single array of supported extensions
   getSupportedFileExtensions: function () {
     const engineNames = Object.keys(PatternEngines);
-    return engineNames.map(function (engineName) {
+    const allEnginesExtensions = engineNames.map((engineName) => {
       return PatternEngines[engineName].engineFileExtension;
     });
+    return [].concat.apply([], allEnginesExtensions);
   },
 
   isFileExtensionSupported: function (fileExtension) {

test/pattern_engines_tests.js

@@ -125,7 +125,7 @@ function testProps(object, propTests, test) {
     });
 
     test.ok(object.hasOwnProperty(propName), '"' + propName + '" prop should be present');
-    test.ok(isOneOfTheseTypes, '"' + propName + '" prop should be one of types ' + possibleTypes);
+    test.ok(isOneOfTheseTypes, '"' + propName + '" prop should be one of types ' + possibleTypes + ' but was instead ' + typeof propName);
   }
 
   // go over each property test and run it
@@ -154,7 +154,7 @@ engineNames.forEach(function (engineName) {
       var propertyTests = {
         'engine': ['object', 'function'],
         'engineName': 'string',
-        'engineFileExtension': 'string',
+        'engineFileExtension': ['string', 'object'],
         'renderPattern': 'function',
         'findPartials': 'function'
       };
@@ -164,3 +164,24 @@ engineNames.forEach(function (engineName) {
       test.end();
   });
 });
+
+tap.test('patternEngines getSupportedFileExtensions flattens known engine extensions into a single array', function (test) {
+
+  //arrange
+  patternEngines.fooEngine = {
+    engineFileExtension : ['.foo1', '.foo2']
+  };
+  patternEngines.barEngine = {
+    engineFileExtension : '.bar'
+  };
+
+  const exts = patternEngines.getSupportedFileExtensions();
+  test.ok(exts.includes('.foo1'));
+  test.ok(exts.includes('.foo2'));
+  test.ok(exts.includes('.bar'));
+
+  delete patternEngines.fooEngine;
+  delete patternEngines.barEngine;
+
+  test.end();
+});