Fix aggregation parsing on negated Contains (#407)

Author: mdrakib

README.md

@@ -363,6 +363,7 @@ We'd love your contributions! If you want to contribute please read our [Contrib
 * [@JuliusMikkela](https://github.com/JuliusMikkela)
 * [@imansafari1991](https://github.com/imansafari1991)
 * [@AndersenGans](https://github.com/AndersenGans)
+* [@mdrakib](https://github.com/mdrakib)
 
 <!-- Logo -->
 [Logo]: images/logo.svg

src/Redis.OM/Aggregation/AggregationPredicates/QueryPredicate.cs

@@ -94,6 +94,27 @@ protected override void ValidateAndPushOperand(Expression expression, Stack<stri
             {
                 stack.Push(ExpressionParserUtilities.TranslateMethodExpressions(method));
             }
+            else if (expression is UnaryExpression uni)
+            {
+                var operandStack = new Stack<string>();
+
+                if (uni.Operand is BinaryExpression be)
+                {
+                    SplitBinaryExpression(be, operandStack);
+                }
+                else
+                {
+                    ValidateAndPushOperand(uni.Operand, operandStack);
+                }
+
+                var val = string.Join(" ", operandStack);
+                if (uni.NodeType == ExpressionType.Not)
+                {
+                    val = $"(-({val}))";
+                }
+
+                stack.Push(val);
+            }
             else
             {
                 throw new ArgumentException("Invalid Expression Type");

test/Redis.OM.Unit.Tests/RediSearchTests/AggregationFunctionalTests.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using Redis.OM.Aggregation;
 using Redis.OM.Contracts;
 using System.Threading.Tasks;
@@ -285,5 +286,21 @@ public async Task GetGroupCountWithNegationQuery()
                 Assert.True(1 <= result["COUNT"]);
             }
         }
+
+        [Fact]
+        public async Task TestListNotContains()
+        {
+            Setup();
+            var collection = new RedisAggregationSet<Person>(_connection);
+            
+            var names = new List<string> { "Beaker", "Rakib" };
+            var people = await collection
+                .Where(x => !names.Contains(x.RecordShell.Name) && x.RecordShell.Name != "fake")
+                .Load(x => x.RecordShell.Name)
+                .ToListAsync();
+
+            Assert.Contains(people, x => x.Hydrate().Name == "Statler");
+            Assert.DoesNotContain(people, x => x.Hydrate().Name == "Beaker");
+        }
     }
 }