ProperyNameJsonConverter and field resolver for propertyname was new'…

…ing an Inferrer (#3030)

src/Nest/CommonAbstractions/ConnectionSettings/ConnectionSettingsBase.cs

@@ -19,6 +19,13 @@ public class ConnectionSettings : ConnectionSettingsBase<ConnectionSettings>
 		public ConnectionSettings(Uri uri = null)
 			: this(new SingleNodeConnectionPool(uri ?? new Uri("http://localhost:9200"))) { }
 
+		/// <summary>
+		/// Instantiate connection settings using a <see cref="SingleNodeConnectionPool"/> using the provided
+		/// <see cref="InMemoryConnection"/> that never uses any IO.
+		/// </summary>
+		public ConnectionSettings(InMemoryConnection connection)
+			: this(new SingleNodeConnectionPool(new Uri("http://localhost:9200")), connection) { }
+
 		public ConnectionSettings(IConnectionPool connectionPool) : this(connectionPool, null, null) { }
 
 		public ConnectionSettings(IConnectionPool connectionPool, SourceSerializerFactory sourceSerializer)

src/Nest/CommonAbstractions/Extensions/ExpressionExtensions.cs

@@ -24,11 +24,11 @@ public static Expression<Func<T, object>> AppendSuffix<T>(this Expression<Func<T
 		/// </summary>
 		private class SuffixExpressionVisitor : ExpressionVisitor
 		{
-			private readonly string suffix;
+			private readonly string _suffix;
 
 			public SuffixExpressionVisitor(string suffix)
 			{
-				this.suffix = suffix;
+				this._suffix = suffix;
 			}
 
 			public override Expression Visit(Expression node)
@@ -38,13 +38,10 @@ public override Expression Visit(Expression node)
 					nameof(SuffixExtensions.Suffix),
 					null,
 					node,
-					Expression.Constant(suffix));
+					Expression.Constant(_suffix));
 			}
 
-			protected override Expression VisitUnary(UnaryExpression node)
-			{
-				return node;
-			}
+			protected override Expression VisitUnary(UnaryExpression node) => node;
 		}
 
 		private static readonly Regex ExpressionRegex = new Regex(@"^\s*(.*)\s*\=\>\s*\1\.");
@@ -56,14 +53,12 @@ internal static object ComparisonValueFromExpression(this Expression expression,
 
 			if (expression == null) return null;
 
-			var lambda = expression as LambdaExpression;
-			if (lambda == null)
+			if (!(expression is LambdaExpression lambda))
 				return ExpressionRegex.Replace(expression.ToString(), string.Empty);
 
 			type = lambda.Parameters.FirstOrDefault()?.Type;
 
-			var memberExpression = lambda.Body as MemberExpression;
-			return memberExpression != null
+			return lambda.Body is MemberExpression memberExpression
 				? MemberExpressionRegex.Replace(memberExpression.ToString(), string.Empty)
 				: ExpressionRegex.Replace(expression.ToString(), string.Empty);
 		}

src/Nest/CommonAbstractions/Infer/Field/FieldExpressionVisitor.cs

@@ -151,8 +151,7 @@ protected override Expression VisitMethodCall(MethodCallExpression methodCall)
 		private static void VisitConstantOrVariable(MethodCallExpression methodCall, Stack<string> stack)
 		{
 			var lastArg = methodCall.Arguments.Last();
-			var constantExpression = lastArg as ConstantExpression;
-			var value = constantExpression != null
+			var value = lastArg is ConstantExpression constantExpression
 				? constantExpression.Value.ToString()
 				: Expression.Lambda(lastArg).Compile().DynamicInvoke().ToString();
 			stack.Push(value);

src/Nest/CommonAbstractions/Infer/Field/FieldResolver.cs

@@ -42,8 +42,7 @@ private string ResolveFieldName(Field field)
 				return this.Resolve(field.Expression, field.Property);
 			}
 
-			string fieldName;
-			if (this.Fields.TryGetValue(field, out fieldName))
+			if (this.Fields.TryGetValue(field, out var fieldName))
 				return fieldName;
 
 			fieldName = this.Resolve(field.Expression, field.Property);
@@ -61,8 +60,7 @@ public string Resolve(PropertyName property)
 				return this.Resolve(property.Expression, property.Property);
 			}
 
-			string propertyName;
-			if (this.Properties.TryGetValue(property, out propertyName))
+			if (this.Properties.TryGetValue(property, out var propertyName))
 				return propertyName;
 
 			propertyName = this.Resolve(property.Expression, property.Property, true);

src/Nest/CommonAbstractions/Infer/Id/IdResolver.cs

@@ -25,9 +25,9 @@ internal Func<T, string> CreateIdSelector<T>() where T : class
 			return idSelector;
 		}
 
-		internal static Func<object, object> MakeDelegate<T, U>(MethodInfo @get)
+		internal static Func<object, object> MakeDelegate<T, TReturn>(MethodInfo @get)
 		{
-			var f = (Func<T, U>)@get.CreateDelegate(typeof(Func<T, U>));
+			var f = (Func<T, TReturn>)@get.CreateDelegate(typeof(Func<T, TReturn>));
 			return t => f((T)t);
 		}
 
@@ -37,12 +37,9 @@ public string Resolve(Type type, object @object)
 		{
 			if (type == null || @object == null) return null;
 
-			Func<object, string> cachedLookup;
-			string field;
+			var preferLocal = this._connectionSettings.IdProperties.TryGetValue(type, out _);
 
-			var preferLocal = this._connectionSettings.IdProperties.TryGetValue(type, out field);
-
-			if (LocalIdDelegates.TryGetValue(type, out cachedLookup))
+			if (LocalIdDelegates.TryGetValue(type, out var cachedLookup))
 				return cachedLookup(@object);
 
 			if (!preferLocal && IdDelegates.TryGetValue(type, out cachedLookup))
@@ -55,7 +52,7 @@ public string Resolve(Type type, object @object)
 			}
 			var getMethod = idProperty.GetGetMethod();
 			var generic = MakeDelegateMethodInfo.MakeGenericMethod(type, getMethod.ReturnType);
-			var func = (Func<object, object>)generic.Invoke(null, new[] { getMethod });
+			var func = (Func<object, object>)generic.Invoke(null, new object[] { getMethod });
 			cachedLookup = o =>
 			{
 				var v = func(o);

src/Nest/CommonAbstractions/Infer/PropertyName/PropertyName.cs

@@ -33,10 +33,9 @@ public PropertyName(string name)
 
 		public PropertyName(Expression expression)
 		{
-			Type type;
 			Expression = expression;
 			CacheableExpression = !new HasVariableExpressionVisitor(expression).Found;
-			_comparisonValue = expression.ComparisonValueFromExpression(out type);
+			_comparisonValue = expression.ComparisonValueFromExpression(out var type);
 			_type = type;
 		}
 
@@ -86,10 +85,8 @@ public override bool Equals(object obj)
 		string IUrlParameter.GetString(IConnectionConfigurationValues settings)
 		{
 			var nestSettings = settings as IConnectionSettingsValues;
-			if (nestSettings == null)
-				throw new Exception("Tried to pass field name on querysting but it could not be resolved because no nest settings are available");
-			var infer = new Inferrer(nestSettings);
-			return infer.PropertyName(this);
+
+			return nestSettings?.Inferrer.PropertyName(this);
 		}
 	}
 }

src/Nest/CommonAbstractions/Infer/PropertyName/PropertyNameJsonConverter.cs

@@ -19,7 +19,8 @@ public override void WriteJson(JsonWriter writer, object value, JsonSerializer s
 				writer.WriteNull();
 				return;
 			}
-			writer.WriteValue(new Inferrer(serializer.GetConnectionSettings()).PropertyName(property));
+			var infer = serializer.GetConnectionSettings().Inferrer;
+			writer.WriteValue(infer.PropertyName(property));
 		}
 		public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
 		{