Fixes regression where a null ColumntSet could crash the new Aggregat…

src/FakeXrmEasy.Core/Query/QueryExpressionExtensions.cs

@@ -73,14 +73,14 @@
 
             var linkedEntities = new Dictionary<string, int>();
 
             bool hasAggregates = false;
 
 #if  !FAKE_XRM_EASY
             ValidateAliases(qe, context as XrmFakedContext);
 #endif
 #if FAKE_XRM_EASY_9
             var aggregateExpressions = GetAggregateAttributeExpressions(qe);
-            hasAggregates = aggregateExpressions.Count > 0;
+            hasAggregates = aggregateExpressions?.Count > 0;
             ValidateAggregates(qe, aggregateExpressions);
 #endif
 
@@ -147,7 +147,7 @@
         #if FAKE_XRM_EASY_9
         private static List<XrmAttributeExpression> GetAggregateAttributeExpressions(QueryExpression qe)
         {
-            return qe.ColumnSet
+            return qe.ColumnSet?
                 .AttributeExpressions
                 .Where(ae => ae.AggregateType != XrmAggregateType.None)
                 .ToList();
@@ -197,6 +197,11 @@
 
         private static void ValidateAggregates(QueryExpression qe, List<XrmAttributeExpression> attributeExpressions)
         {
+            if (qe.ColumnSet == null)
+            {
+                return;
+            }
+
             var hasAggregateAttributeExpressions =
                 attributeExpressions.Count > 0;
 

tests/FakeXrmEasy.Core.Tests/Query/QueryByAttribute/QueryByAttributeTests.cs

@@ -223,6 +223,35 @@ public void TopCount_is_respected_for_query_by_attribute()
             Assert.Equal(5, results.Entities.Count);
         }
 
+        [Fact]
+        public void Should_execute_a_query_without_a_specific_column_set()
+        {
+            var contact1 = new Contact
+            {
+                Id = Guid.NewGuid(),
+                LastName = "asdf"
+            };
+
+            var contact2 = new Contact
+            {
+                Id = Guid.NewGuid(),
+                LastName = "qwer"
+            };
+
+            _context.Initialize(new List<Entity> { contact1, contact2 });
+
+            QueryByAttribute query = new QueryByAttribute("contact");
+            query.PageInfo = new PagingInfo()
+            {
+                PageNumber = 1,
+                Count = 1,
+                ReturnTotalRecordCount = true
+            };
+            var results = _service.RetrieveMultiple(query);
+
+            Assert.Single(results.Entities);
+            Assert.Equal(2, results.TotalRecordCount);
+        }
 
     }
 }