Include missing paths in MaxRetryExceededError instances

this will help developers understand data source and service failures better

lib/errors/MaxRetryExceededError.js

@@ -5,8 +5,9 @@ var NAME = "MaxRetryExceededError";
  *
  * @private
  */
-function MaxRetryExceededError() {
+function MaxRetryExceededError(missingPaths) {
     this.message = "The allowed number of retries have been exceeded.";
+    this.missingPaths = missingPaths || [];
     this.stack = (new Error()).stack;
 }
 

lib/response/get/getRequestCycle.js

@@ -23,7 +23,7 @@ module.exports = function getRequestCycle(getResponse, model, results, observer,
                                           errors, count) {
     // we have exceeded the maximum retry limit.
     if (count === model._maxRetries) {
-        observer.onError(new MaxRetryExceededError());
+        observer.onError(new MaxRetryExceededError(results.requestedMissingPaths));
         return {
             dispose: function() {}
         };

lib/response/set/setRequestCycle.js

@@ -12,17 +12,18 @@ var MaxRetryExceededError = require("./../../errors/MaxRetryExceededError");
  */
 module.exports = function setRequestCycle(model, observer, groups,
                                           isJSONGraph, isProgressive, count) {
+    var requestedAndOptimizedPaths = setGroupsIntoCache(model, groups);
+    var optimizedPaths = requestedAndOptimizedPaths.optimizedPaths;
+    var requestedPaths = requestedAndOptimizedPaths.requestedPaths;
+
     // we have exceeded the maximum retry limit.
     if (count === model._maxRetries) {
-        observer.onError(new MaxRetryExceededError());
+        observer.onError(new MaxRetryExceededError(requestedPaths));
         return {
             dispose: function() {}
         };
     }
 
-    var requestedAndOptimizedPaths = setGroupsIntoCache(model, groups);
-    var optimizedPaths = requestedAndOptimizedPaths.optimizedPaths;
-    var requestedPaths = requestedAndOptimizedPaths.requestedPaths;
     var isMaster = model._source === undefined;
 
     // Local set only.  We perform a follow up get.  If performance is ever

package.json

@@ -15,6 +15,7 @@
   "license": "Apache-2.0",
   "scripts": {
     "test": "gulp test-coverage",
+    "test:only": "mocha test/index.js",
     "dist": "gulp all",
     "doc": "gulp doc",
     "perf": "gulp perf-run",

test/falcor/get/get.dataSource-only.spec.js

@@ -341,8 +341,24 @@ describe('DataSource Only', function() {
                 return done();
             }, done.bind('should not complete'));
     });
+
+    it('should return missing paths with MaxRetryExceededError', function(done) {
+        var model = new Model({ source: asyncifyDataSource(new LocalDataSource({})) });
+        toObservable(model.
+            get(['videos', 0, 'title'], 'hall[0].ween')).
+            doAction(noOp, function(e) {
+                expect(MaxRetryExceededError.is(e), 'MaxRetryExceededError expected.').to.be.ok;
+                expect(e.missingPaths).to.deep.equals([['videos', 0, 'title'], ['hall', 0, 'ween']]);
+            }).
+            subscribe(noOp, function(e) {
+                if (isAssertionError(e)) {
+                    return done(e);
+                }
+                return done();
+            }, done.bind('should not complete'));
+    });
 });
 
 function isAssertionError(e) {
     return e.hasOwnProperty('expected') && e.hasOwnProperty('actual');
-}
+}