Fix error handling in Deferred's promise functions

lib/waterline/query/deferred.js

@@ -239,62 +239,36 @@ Deferred.prototype.done = function(cb) {
  * Executes a Query, and returns a promise
  */
 
-Deferred.prototype.then = function(cb, ec) {
+Deferred.prototype.toPromise = function() {
   var deferred = Q.defer();
 
-  this.exec(function(err, result) {
-    if(err) {
-      if(typeof ec === 'function') {
-        deferred.resolve(ec(err));
-      } else {
-        deferred.reject(err);
-      }
-    } else {
-      cb ? deferred.resolve(cb(result)) : deferred.resolve(result);
-    }
-  });
+  this.exec(deferred.makeNodeResolver());
 
   return deferred.promise;
 };
 
 /**
- * Applies results to function fn.apply, and returns a promise
+ * Executes a Query, and returns a promise that applies cb/ec to the
+ * result/error.
  */
 
-Deferred.prototype.spread = function(cb) {
-  var deferred = Q.defer();
+Deferred.prototype.then = function(cb, ec) {
+  return this.toPromise().then(cb, ec);
+};
 
-  this.exec(function(err, result) {
-    if(err) {
-        deferred.reject(err);
-    } else {
-
-      if(!(result instanceof Array)) {
-        cb ? deferred.resolve(cb(result)) : deferred.resolve(result);
-      } else {
-        cb ? deferred.resolve(cb.apply(cb, result)) : deferred.resolve(result);
-      }
-    }
-  });
+/**
+ * Applies results to function fn.apply, and returns a promise
+ */
 
-  return deferred.promise;
+Deferred.prototype.spread = function(cb) {
+  return this.toPromise().spread(cb);
 };
 
 /**
  * returns a promise and gets resolved with error
  */
 
 Deferred.prototype.fail = function(cb) {
-  var deferred = Q.defer();
-
-  this.exec(function(err, result) {
-    if(err) {
-      cb ? deferred.resolve(cb(err)) : deferred.reject(err);
-    } else {
-      deferred.resolve(result);
-    }
-  });
-
-  return deferred.promise;
+  return this.toPromise().fail(cb);
 };
 

test/unit/query/query.promises.js

@@ -49,5 +49,25 @@ describe('Collection Promise', function () {
         done(err);
       });
     });
+
+    it('should reject the promise if the then handler fails', function (done) {
+      var promise = query.find({}).then(function (obj) {
+        throw new Error("Error in promise handler");
+      }).then(function (unexpected) {
+        done(new Error("Unexpected success"));
+      }).fail(function (expected) {
+        done();
+      })
+    });
+
+    it('should reject the promise if the spread handler fails', function (done) {
+      var promise = query.find({}).spread(function (obj) {
+        throw new Error("Error in promise handler");
+      }).then(function (unexpected) {
+        done(new Error("Unexpected success"));
+      }).fail(function (expected) {
+        done();
+      })
+    });
   });
-});
+});