diff --git a/tests/FSharp.Data.Core.Tests/FSharp.Data.Core.Tests.fsproj b/tests/FSharp.Data.Core.Tests/FSharp.Data.Core.Tests.fsproj
index b85fa7803..94f0b2e9b 100644
--- a/tests/FSharp.Data.Core.Tests/FSharp.Data.Core.Tests.fsproj
+++ b/tests/FSharp.Data.Core.Tests/FSharp.Data.Core.Tests.fsproj
@@ -38,6 +38,7 @@
     <Compile Include="HtmlOperations.fs" />
     <Compile Include="HtmlAttributeExtensions.fs" />
     <Compile Include="HtmlCssSelectors.fs" />
+    <Compile Include="StructuralTypes.fs" />
     <Compile Include="BaseTypesHtmlDocument.fs" />
     <Compile Include="XmlExtensions.fs" />
     <Compile Include="WorldBankRuntime.fs" />
@@ -63,6 +64,10 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>
+    <PackageReference Include="coverlet.msbuild" Version="6.0.4">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
   </ItemGroup>
   <Import Project="..\..\.paket\Paket.Restore.targets" />
 </Project>
diff --git a/tests/FSharp.Data.Core.Tests/StructuralTypes.fs b/tests/FSharp.Data.Core.Tests/StructuralTypes.fs
new file mode 100644
index 000000000..7451b96f0
--- /dev/null
+++ b/tests/FSharp.Data.Core.Tests/StructuralTypes.fs
@@ -0,0 +1,338 @@
+module FSharp.Data.Tests.StructuralTypes
+
+open NUnit.Framework
+open FsUnit
+open System
+open FSharp.Data.Runtime.StructuralTypes
+
+[<TestFixture>]
+type InferedPropertyTests() =
+
+    [<Test>]
+    member _.``InferedProperty can be created with name and type``() =
+        let inferredType = InferedType.Primitive(typeof<string>, None, false, false)
+        let property = { Name = "TestProperty"; Type = inferredType }
+        
+        property.Name |> should equal "TestProperty"
+        property.Type |> should equal inferredType
+
+    [<Test>]
+    member _.``InferedProperty Type field is mutable``() =
+        let initialType = InferedType.Primitive(typeof<int>, None, false, false)
+        let newType = InferedType.Primitive(typeof<string>, None, false, false)
+        let property = { Name = "TestProperty"; Type = initialType }
+        
+        property.Type <- newType
+        property.Type |> should equal newType
+
+    [<Test>]
+    member _.``InferedProperty ToString produces meaningful output``() =
+        let inferredType = InferedType.Primitive(typeof<string>, None, false, false)
+        let property = { Name = "TestProperty"; Type = inferredType }
+        
+        let result = property.ToString()
+        result |> should contain "TestProperty"
+        result |> should contain "Primitive"
+
+    [<Test>]
+    member _.``InferedProperty with complex type structure``() =
+        let recordProperties = [
+            { Name = "Field1"; Type = InferedType.Primitive(typeof<int>, None, false, false) }
+            { Name = "Field2"; Type = InferedType.Primitive(typeof<string>, None, false, false) }
+        ]
+        let recordType = InferedType.Record(Some("TestRecord"), recordProperties, false)
+        let property = { Name = "ComplexProperty"; Type = recordType }
+        
+        property.Name |> should equal "ComplexProperty"
+        match property.Type with
+        | InferedType.Record(Some("TestRecord"), fields, false) -> 
+            fields |> should haveLength 2
+            fields.[0].Name |> should equal "Field1"
+            fields.[1].Name |> should equal "Field2"
+        | _ -> failwith "Expected Record type"
+
+[<TestFixture>]
+type InferedTypeTagTests() =
+
+    [<Test>]
+    member _.``InferedTypeTag NiceName returns correct values``() =
+        InferedTypeTag.Number.NiceName |> should equal "Number"
+        InferedTypeTag.Boolean.NiceName |> should equal "Boolean"
+        InferedTypeTag.String.NiceName |> should equal "String"
+        InferedTypeTag.DateTime.NiceName |> should equal "DateTime"
+        InferedTypeTag.TimeSpan.NiceName |> should equal "TimeSpan"
+        InferedTypeTag.DateTimeOffset.NiceName |> should equal "DateTimeOffset"
+        InferedTypeTag.Guid.NiceName |> should equal "Guid"
+        InferedTypeTag.Collection.NiceName |> should equal "Array"
+        InferedTypeTag.Heterogeneous.NiceName |> should equal "Choice"
+        InferedTypeTag.Json.NiceName |> should equal "Json"
+        (InferedTypeTag.Record None).NiceName |> should equal "Record"
+
+    [<Test>]
+    member _.``InferedTypeTag NiceName for named record``() =
+        (InferedTypeTag.Record (Some "TestRecord")).NiceName |> should equal "TestRecord"
+
+    [<Test>]
+    member _.``InferedTypeTag Code returns correct values``() =
+        InferedTypeTag.Number.Code |> should equal "Number"
+        InferedTypeTag.Boolean.Code |> should equal "Boolean"
+        InferedTypeTag.String.Code |> should equal "String"
+        InferedTypeTag.Collection.Code |> should equal "Array"
+        (InferedTypeTag.Record None).Code |> should equal "Record"
+        (InferedTypeTag.Record (Some "TestRecord")).Code |> should equal "Record@TestRecord"
+
+    [<Test>]
+    member _.``InferedTypeTag ParseCode correctly parses code values``() =
+        InferedTypeTag.ParseCode("Number") |> should equal InferedTypeTag.Number
+        InferedTypeTag.ParseCode("Boolean") |> should equal InferedTypeTag.Boolean
+        InferedTypeTag.ParseCode("String") |> should equal InferedTypeTag.String
+        InferedTypeTag.ParseCode("DateTime") |> should equal InferedTypeTag.DateTime
+        InferedTypeTag.ParseCode("TimeSpan") |> should equal InferedTypeTag.TimeSpan
+        InferedTypeTag.ParseCode("DateTimeOffset") |> should equal InferedTypeTag.DateTimeOffset
+        InferedTypeTag.ParseCode("Guid") |> should equal InferedTypeTag.Guid
+        InferedTypeTag.ParseCode("Array") |> should equal InferedTypeTag.Collection
+        InferedTypeTag.ParseCode("Choice") |> should equal InferedTypeTag.Heterogeneous
+        InferedTypeTag.ParseCode("Json") |> should equal InferedTypeTag.Json
+        InferedTypeTag.ParseCode("Record") |> should equal (InferedTypeTag.Record None)
+        InferedTypeTag.ParseCode("Record@TestRecord") |> should equal (InferedTypeTag.Record (Some "TestRecord"))
+
+    [<Test>]
+    member _.``InferedTypeTag ParseCode throws for Null``() =
+        (fun () -> InferedTypeTag.ParseCode("Null") |> ignore) 
+        |> should throw typeof<System.Exception>
+
+    [<Test>]
+    member _.``InferedTypeTag ParseCode throws for invalid code``() =
+        (fun () -> InferedTypeTag.ParseCode("InvalidCode") |> ignore) 
+        |> should throw typeof<System.Exception>
+
+    [<Test>]
+    member _.``InferedTypeTag NiceName throws for Null``() =
+        (fun () -> InferedTypeTag.Null.NiceName |> ignore) 
+        |> should throw typeof<System.Exception>
+
+[<TestFixture>]
+type InferedMultiplicityTests() =
+
+    [<Test>]
+    member _.``InferedMultiplicity struct values work correctly``() =
+        let single = InferedMultiplicity.Single
+        let optionalSingle = InferedMultiplicity.OptionalSingle
+        let multiple = InferedMultiplicity.Multiple
+        
+        single |> should not' (equal optionalSingle)
+        single |> should not' (equal multiple)
+        optionalSingle |> should not' (equal multiple)
+
+[<TestFixture>]
+type InferedTypeTests() =
+
+    [<Test>]
+    member _.``InferedType IsOptional returns correct values``() =
+        let primitiveOptional = InferedType.Primitive(typeof<string>, None, true, false)
+        let primitiveRequired = InferedType.Primitive(typeof<string>, None, false, false)
+        let recordOptional = InferedType.Record(None, [], true)
+        let recordRequired = InferedType.Record(None, [], false)
+        let jsonOptional = InferedType.Json(InferedType.Primitive(typeof<string>, None, false, false), true)
+        let jsonRequired = InferedType.Json(InferedType.Primitive(typeof<string>, None, false, false), false)
+        
+        primitiveOptional.IsOptional |> should equal true
+        primitiveRequired.IsOptional |> should equal false
+        recordOptional.IsOptional |> should equal true
+        recordRequired.IsOptional |> should equal false
+        jsonOptional.IsOptional |> should equal true
+        jsonRequired.IsOptional |> should equal false
+        InferedType.Null.IsOptional |> should equal false
+        InferedType.Top.IsOptional |> should equal false
+
+    [<Test>]
+    member _.``InferedType CanHaveEmptyValues works correctly``() =
+        InferedType.CanHaveEmptyValues(typeof<string>) |> should equal true
+        InferedType.CanHaveEmptyValues(typeof<float>) |> should equal true
+        InferedType.CanHaveEmptyValues(typeof<int>) |> should equal false
+        InferedType.CanHaveEmptyValues(typeof<bool>) |> should equal false
+
+    [<Test>]
+    member _.``InferedType EnsuresHandlesMissingValues with allowEmptyValues true``() =
+        let primitiveString = InferedType.Primitive(typeof<string>, None, false, false)
+        let primitiveInt = InferedType.Primitive(typeof<int>, None, false, false)
+        
+        let result1 = primitiveString.EnsuresHandlesMissingValues(true)
+        let result2 = primitiveInt.EnsuresHandlesMissingValues(true)
+        
+        result1 |> should equal primitiveString  // string can have empty values, so no change
+        match result2 with
+        | InferedType.Primitive(typ, _, true, _) when typ = typeof<int> -> ()
+        | _ -> failwith "Expected optional int primitive"
+
+    [<Test>]
+    member _.``InferedType EnsuresHandlesMissingValues with allowEmptyValues false``() =
+        let primitiveString = InferedType.Primitive(typeof<string>, None, false, false)
+        
+        let result = primitiveString.EnsuresHandlesMissingValues(false)
+        
+        match result with
+        | InferedType.Primitive(typ, _, true, _) when typ = typeof<string> -> ()
+        | _ -> failwith "Expected optional string primitive"
+
+    [<Test>]
+    member _.``InferedType EnsuresHandlesMissingValues handles already optional types``() =
+        let primitiveOptional = InferedType.Primitive(typeof<string>, None, true, false)
+        let recordOptional = InferedType.Record(None, [], true)
+        let jsonOptional = InferedType.Json(InferedType.Primitive(typeof<string>, None, false, false), true)
+        
+        primitiveOptional.EnsuresHandlesMissingValues(false) |> should equal primitiveOptional
+        recordOptional.EnsuresHandlesMissingValues(false) |> should equal recordOptional
+        jsonOptional.EnsuresHandlesMissingValues(false) |> should equal jsonOptional
+
+    [<Test>]
+    member _.``InferedType EnsuresHandlesMissingValues handles Null and Top``() =
+        InferedType.Null.EnsuresHandlesMissingValues(false) |> should equal InferedType.Null
+        
+        (fun () -> InferedType.Top.EnsuresHandlesMissingValues(false) |> ignore)
+        |> should throw typeof<System.Exception>
+
+    [<Test>]
+    member _.``InferedType GetDropOptionality returns correct values``() =
+        let primitiveOptional = InferedType.Primitive(typeof<string>, None, true, false)
+        let primitiveRequired = InferedType.Primitive(typeof<string>, None, false, false)
+        
+        let result1, wasOptional1 = primitiveOptional.GetDropOptionality()
+        let result2, wasOptional2 = primitiveRequired.GetDropOptionality()
+        
+        match result1 with
+        | InferedType.Primitive(typ, _, false, _) when typ = typeof<string> -> ()
+        | _ -> failwith "Expected non-optional string primitive"
+        wasOptional1 |> should equal true
+        
+        result2 |> should equal primitiveRequired
+        wasOptional2 |> should equal false
+
+    [<Test>]
+    member _.``InferedType DropOptionality works correctly``() =
+        let primitiveOptional = InferedType.Primitive(typeof<string>, None, true, false)
+        
+        let result = primitiveOptional.DropOptionality()
+        
+        match result with
+        | InferedType.Primitive(typ, _, false, _) when typ = typeof<string> -> ()
+        | _ -> failwith "Expected non-optional string primitive"
+
+    [<Test>]
+    member _.``InferedType Equals works with reference equality``() =
+        let type1 = InferedType.Primitive(typeof<string>, None, false, false)
+        let type2 = type1  // same reference
+        let type3 = InferedType.Primitive(typeof<string>, None, false, false)  // different reference, same content
+        
+        type1.Equals(type2) |> should equal true
+        type1.Equals(type3) |> should equal true
+
+    [<Test>]
+    member _.``InferedType Equals works with structural equality``() =
+        let type1 = InferedType.Primitive(typeof<string>, None, false, false)
+        let type2 = InferedType.Primitive(typeof<string>, None, false, false)
+        let type3 = InferedType.Primitive(typeof<int>, None, false, false)
+        
+        type1.Equals(type2) |> should equal true
+        type1.Equals(type3) |> should equal false
+
+    [<Test>]
+    member _.``InferedType Equals with different types returns false``() =
+        let inferredType = InferedType.Primitive(typeof<string>, None, false, false)
+        let otherObject = "not an InferedType"
+        
+        inferredType.Equals(otherObject) |> should equal false
+
+    [<Test>]
+    member _.``InferedType ToString produces meaningful output``() =
+        let primitiveType = InferedType.Primitive(typeof<string>, None, false, false)
+        let nullType = InferedType.Null
+        let topType = InferedType.Top
+        
+        primitiveType.ToString() |> should contain "Primitive"
+        nullType.ToString() |> should contain "Null"  
+        topType.ToString() |> should contain "Top"
+
+[<TestFixture>]
+type PrimitiveInferedValueTests() =
+
+    [<Test>]
+    member _.``PrimitiveInferedValue Create with TypeWrapper works correctly``() =
+        let result = PrimitiveInferedValue.Create(typeof<string>, TypeWrapper.Option, Some(typeof<int>))
+        
+        result.InferedType |> should equal typeof<string>
+        result.RuntimeType |> should equal typeof<string>
+        result.UnitOfMeasure |> should equal (Some(typeof<int>))
+        result.TypeWrapper |> should equal TypeWrapper.Option
+
+    [<Test>]
+    member _.``PrimitiveInferedValue Create with optional boolean works correctly``() =
+        let result = PrimitiveInferedValue.Create(typeof<float>, true, None)
+        
+        result.InferedType |> should equal typeof<float>
+        result.RuntimeType |> should equal typeof<float>
+        result.UnitOfMeasure |> should equal None
+        result.TypeWrapper |> should equal TypeWrapper.Option
+
+    [<Test>]
+    member _.``PrimitiveInferedValue Create handles Bit types correctly``() =
+        let bitResult = PrimitiveInferedValue.Create(typeof<Bit>, TypeWrapper.None, None)
+        let bit0Result = PrimitiveInferedValue.Create(typeof<Bit0>, TypeWrapper.None, None)
+        let bit1Result = PrimitiveInferedValue.Create(typeof<Bit1>, TypeWrapper.None, None)
+        
+        bitResult.InferedType |> should equal typeof<Bit>
+        bitResult.RuntimeType |> should equal typeof<bool>
+        
+        bit0Result.InferedType |> should equal typeof<Bit0>
+        bit0Result.RuntimeType |> should equal typeof<int>
+        
+        bit1Result.InferedType |> should equal typeof<Bit1>
+        bit1Result.RuntimeType |> should equal typeof<int>
+
+[<TestFixture>]
+type PrimitiveInferedPropertyTests() =
+
+    [<Test>]
+    member _.``PrimitiveInferedProperty Create with TypeWrapper works correctly``() =
+        let result = PrimitiveInferedProperty.Create("TestProp", typeof<string>, TypeWrapper.Nullable, Some(typeof<float>))
+        
+        result.Name |> should equal "TestProp"
+        result.Value.InferedType |> should equal typeof<string>
+        result.Value.TypeWrapper |> should equal TypeWrapper.Nullable
+        result.Value.UnitOfMeasure |> should equal (Some(typeof<float>))
+
+    [<Test>]
+    member _.``PrimitiveInferedProperty Create with optional boolean works correctly``() =
+        let result = PrimitiveInferedProperty.Create("OptionalProp", typeof<int>, false, None)
+        
+        result.Name |> should equal "OptionalProp"
+        result.Value.InferedType |> should equal typeof<int>
+        result.Value.TypeWrapper |> should equal TypeWrapper.None
+        result.Value.UnitOfMeasure |> should equal None
+
+[<TestFixture>]
+type TypeWrapperTests() =
+
+    [<Test>]
+    member _.``TypeWrapper FromOption returns correct values``() =
+        TypeWrapper.FromOption(true) |> should equal TypeWrapper.Option
+        TypeWrapper.FromOption(false) |> should equal TypeWrapper.None
+
+[<TestFixture>]
+type BitTypesTests() =
+
+    [<Test>]
+    member _.``Bit types are struct types``() =
+        typeof<Bit>.IsValueType |> should equal true
+        typeof<Bit0>.IsValueType |> should equal true
+        typeof<Bit1>.IsValueType |> should equal true
+
+    [<Test>]
+    member _.``Bit types equality works``() =
+        let bit = Bit.Bit
+        let bit0 = Bit0.Bit0
+        let bit1 = Bit1.Bit1
+        
+        bit |> should equal Bit.Bit
+        bit0 |> should equal Bit0.Bit0
+        bit1 |> should equal Bit1.Bit1
\ No newline at end of file