Make SqlType.Equals symmetrical (#2534)

Author: bahusoid

src/NHibernate.Test/TypesTest/ChangeDefaultTypeWithLengthFixture.cs

@@ -68,16 +68,16 @@ public void PropertyType()
 			var propertyType25 = Sfi.GetClassMetadata(typeof(ChangeDefaultTypeClass))
 								.GetPropertyType(nameof(ChangeDefaultTypeClass.StringTypeLengthInType25));
 			Assert.That(
-				propertyType25,
-				Is.EqualTo(_testDefaultStringType));
+				propertyType25.GetType(),
+				Is.EqualTo(_testDefaultStringType.GetType()));
 			Assert.That(propertyType25.SqlTypes(Sfi)[0].Length, Is.EqualTo(25));
 
 			var propertyType20 = Sfi.GetClassMetadata(typeof(ChangeDefaultTypeClass))
 								.GetPropertyType(nameof(ChangeDefaultTypeClass.StringTypeExplicitLength20));
 
 			Assert.That(
-				propertyType20,
-				Is.EqualTo(_testDefaultStringType));
+				propertyType20.GetType(),
+				Is.EqualTo(_testDefaultStringType.GetType()));
 			Assert.That(propertyType20.SqlTypes(Sfi)[0].Length, Is.EqualTo(20));
 		}
 

src/NHibernate.Test/TypesTest/ChangeDefaultTypeWithPrecisionFixture.cs

@@ -69,17 +69,17 @@ public void PropertyType()
 			var propertyType1 = Sfi.GetClassMetadata(typeof(ChangeDefaultTypeClass))
 									.GetPropertyType(nameof(ChangeDefaultTypeClass.CurrencyTypeExplicitPrecision6And3));
 			Assert.That(
-				propertyType1,
-				Is.EqualTo(_testDefaultType));
+				propertyType1.GetType(),
+				Is.EqualTo(_testDefaultType.GetType()));
 			Assert.That(propertyType1.SqlTypes(Sfi)[0].Precision, Is.EqualTo(6));
 			Assert.That(propertyType1.SqlTypes(Sfi)[0].Scale, Is.EqualTo(3));
 
 			var propertyType2 = Sfi.GetClassMetadata(typeof(ChangeDefaultTypeClass))
 									.GetPropertyType(nameof(ChangeDefaultTypeClass.CurrencyTypePrecisionInType5And2));
 
 			Assert.That(
-				propertyType2,
-				Is.EqualTo(_testDefaultType));
+				propertyType2.GetType(),
+				Is.EqualTo(_testDefaultType.GetType()));
 			Assert.That(propertyType2.SqlTypes(Sfi)[0].Precision, Is.EqualTo(5));
 			Assert.That(propertyType2.SqlTypes(Sfi)[0].Scale, Is.EqualTo(2));
 		}

src/NHibernate/SqlTypes/SqlType.cs

@@ -21,7 +21,7 @@ namespace NHibernate.SqlTypes
 	/// </p>
 	/// </remarks>
 	[Serializable]
-	public class SqlType
+	public class SqlType : IEquatable<SqlType>
 	{
 		private readonly DbType dbType;
 		private readonly int length;
@@ -125,24 +125,34 @@ public override bool Equals(object obj)
 
 		public bool Equals(SqlType rhsSqlType)
 		{
+			if (ReferenceEquals(this, rhsSqlType))
+				return true;
+
 			if (rhsSqlType == null)
-			{
 				return false;
-			}
 
-			if (LengthDefined)
-			{
-				return (DbType.Equals(rhsSqlType.DbType)) && (Length == rhsSqlType.Length);
-			}
-			if (PrecisionDefined)
-			{
-				return (DbType.Equals(rhsSqlType.DbType)) && (Precision == rhsSqlType.Precision) && (Scale == rhsSqlType.Scale);
-			}
-			if (ScaleDefined)
-			{
-				return DbType.Equals(rhsSqlType.DbType) && Scale == rhsSqlType.Scale;
-			}
-			return (DbType.Equals(rhsSqlType.DbType));
+			if (DbType != rhsSqlType.DbType)
+				return false;
+
+			if (LengthDefined != rhsSqlType.LengthDefined)
+				return false;
+
+			if (PrecisionDefined != rhsSqlType.PrecisionDefined)
+				return false;
+
+			if (ScaleDefined != rhsSqlType.ScaleDefined)
+				return false;
+
+			if (Length != rhsSqlType.Length)
+				return false;
+
+			if (Precision != rhsSqlType.Precision)
+				return false;
+
+			if (Scale != rhsSqlType.Scale)
+				return false;
+
+			return true;
 		}
 
 		public override string ToString()