Emitting readonly modifier for SUT & mock fields

docs/examples/AbstractClass.md

@@ -40,7 +40,7 @@ public class TestClassTests
         }
     }
 
-    private TestTestClass _testClass;
+    private readonly TestTestClass _testClass;
 
     public TestClassTests()
     {

docs/examples/AsyncMethod.md

@@ -24,7 +24,7 @@ public class TestClass
 ``` csharp
 public class TestClassTests
 {
-    private TestClass _testClass;
+    private readonly TestClass _testClass;
 
     public TestClassTests()
     {

docs/examples/AutoFixtureMockGeneration.md

@@ -77,9 +77,9 @@ public class AutomaticMockGenerationExample
 ``` csharp
 public class AutomaticMockGenerationExampleTests
 {
-    private AutomaticMockGenerationExample _testClass;
-    private IDummyService _dummyService;
-    private IDummyService2 _dummyService2;
+    private readonly AutomaticMockGenerationExample _testClass;
+    private readonly IDummyService _dummyService;
+    private readonly IDummyService2 _dummyService2;
 
     public AutomaticMockGenerationExampleTests()
     {

docs/examples/AutomaticMockGeneration.md

@@ -135,9 +135,9 @@ public class AutomaticMockGenerationExample
 ``` csharp
 public class AutomaticMockGenerationExampleTests
 {
-    private AutomaticMockGenerationExample _testClass;
-    private IDummyService _dummyService;
-    private IDummyService2 _dummyService2;
+    private readonly AutomaticMockGenerationExample _testClass;
+    private readonly IDummyService _dummyService;
+    private readonly IDummyService2 _dummyService2;
 
     public AutomaticMockGenerationExampleTests()
     {

docs/examples/ConstrainedGenericType.md

@@ -45,7 +45,7 @@ public class TestClass<T, R>
 ``` csharp
 public class TestClass_2Tests
 {
-    private TestClass<T, R> _testClass;
+    private readonly TestClass<T, R> _testClass;
     private T _insta;
     private R _insta2;
 

docs/examples/FrameworksFluentAssertions.md

@@ -36,8 +36,8 @@ public class TestClass
 ``` csharp
 public class TestClassTests
 {
-    private TestClass _testClass;
-    private IDependency _dependency;
+    private readonly TestClass _testClass;
+    private readonly IDependency _dependency;
 
     public TestClassTests()
     {

docs/examples/FrameworksXUnitJustMock.md

@@ -36,8 +36,8 @@ public class TestClass
 ``` csharp
 public class TestClassTests
 {
-    private TestClass _testClass;
-    private IDependency _dependency;
+    private readonly TestClass _testClass;
+    private readonly IDependency _dependency;
 
     public TestClassTests()
     {

docs/examples/FrameworksXUnitNSubstitute.md

@@ -36,8 +36,8 @@ public class TestClass
 ``` csharp
 public class TestClassTests
 {
-    private TestClass _testClass;
-    private IDependency _dependency;
+    private readonly TestClass _testClass;
+    private readonly IDependency _dependency;
 
     public TestClassTests()
     {

docs/examples/GenericMethod.md

@@ -17,7 +17,7 @@ public class GenericSource
 ``` csharp
 public class GenericSourceTests
 {
-    private GenericSource _testClass;
+    private readonly GenericSource _testClass;
 
     public GenericSourceTests()
     {

docs/examples/IComparableTests.md

@@ -44,7 +44,7 @@ public class TestComparableGeneric : IComparable<TestComparableGeneric>, ICompar
 ``` csharp
 public class TestComparableGenericTests
 {
-    private TestComparableGeneric _testClass;
+    private readonly TestComparableGeneric _testClass;
     private int _value;
 
     public TestComparableGenericTests()

docs/examples/IndexerTests.md

@@ -23,7 +23,7 @@ public class TypeWithIndexer
 ``` csharp
 public class TypeWithIndexerTests
 {
-    private TypeWithIndexer _testClass;
+    private readonly TypeWithIndexer _testClass;
 
     public TypeWithIndexerTests()
     {

docs/examples/MappingMethod.md

@@ -31,7 +31,7 @@ public class MappingClass
 ``` csharp
 public class MappingClassTests
 {
-    private MappingClass _testClass;
+    private readonly MappingClass _testClass;
 
     public MappingClassTests()
     {

docs/examples/NullableReferenceTypes.md

@@ -34,10 +34,10 @@ public class TestClass
 ``` csharp
 public class TestClassTests
 {
-    private TestClass _testClass;
+    private readonly TestClass _testClass;
     private string _notNullable;
     private string _nullable;
-    private ITest _testITest;
+    private readonly ITest _testITest;
     private string _someOtherThing;
 
     public TestClassTests()

docs/examples/OperatorOverloading.md

@@ -54,7 +54,7 @@ class Calculator
 ``` csharp
 public class CalculatorTests
 {
-    private Calculator _testClass;
+    private readonly Calculator _testClass;
     private int _n;
 
     public CalculatorTests()

docs/examples/PocoInitialization.md

@@ -28,7 +28,7 @@ public class ConsumingClass
 ``` csharp
 public class ConsumingClassTests
 {
-    private ConsumingClass _testClass;
+    private readonly ConsumingClass _testClass;
     private SomePoco _poco;
 
     public ConsumingClassTests()

docs/examples/PropertyInitializationChecks.md

@@ -23,7 +23,7 @@ public class ExampleClass
 ``` csharp
 public class ExampleClassTests
 {
-    private ExampleClass _testClass;
+    private readonly ExampleClass _testClass;
     private int _identity;
     private string _description;
     private Guid _uniqueCode;

docs/examples/RecordTypeInitProperties.md

@@ -33,7 +33,7 @@ record Person
 ``` csharp
 public class PersonTests
 {
-    private Person _testClass;
+    private readonly Person _testClass;
     private Guid _id;
     private string _firstName;
     private string _middleName;

docs/examples/RecordTypesPrimaryConstructor.md

@@ -11,7 +11,7 @@ public record RecordType(string StringProperty, int IntProperty);
 ``` csharp
 public class RecordTypeTests
 {
-    private RecordType _testClass;
+    private readonly RecordType _testClass;
     private string _stringProperty;
     private int _intProperty;
 

docs/examples/RefAndOutParameters.md

@@ -32,7 +32,7 @@ public class TestClass
 ``` csharp
 public class TestClassTests
 {
-    private TestClass _testClass;
+    private readonly TestClass _testClass;
 
     public TestClassTests()
     {

docs/examples/SimplePoco.md

@@ -16,7 +16,7 @@ public class SomePoco
 ``` csharp
 public class SomePocoTests
 {
-    private SomePoco _testClass;
+    private readonly SomePoco _testClass;
 
     public SomePocoTests()
     {

docs/examples/Singleton.md

@@ -30,7 +30,7 @@ public class TestClass
 ``` csharp
 public class TestClassTests
 {
-    private TestClass _testClass;
+    private readonly TestClass _testClass;
 
     public TestClassTests()
     {

docs/examples/StyleCopCompatibility.md

@@ -35,8 +35,8 @@ public class TestClass
 /// </summary>
 public class TestClassTests
 {
-    private TestClass _testClass;
-    private IDependency _dependency;
+    private readonly TestClass _testClass;
+    private readonly IDependency _dependency;
 
     /// <summary>
     /// Sets up the dependencies required for the tests for <see cref="TestClass"/>.

docs/examples/ValueGeneration.md

@@ -24,7 +24,7 @@ public class Writer
 ``` csharp
 public class WriterTests
 {
-    private Writer _testClass;
+    private readonly Writer _testClass;
 
     public WriterTests()
     {

docs/examples/ValueGenerationWithAutoFixture.md

@@ -24,7 +24,7 @@ public class Writer
 ``` csharp
 public class WriterTests
 {
-    private Writer _testClass;
+    private readonly Writer _testClass;
 
     public WriterTests()
     {

src/Unitverse.Core/Frameworks/ITestFramework.cs

@@ -9,5 +9,7 @@ public interface ITestFramework : IAssertionFramework
         AttributeSyntax? SingleThreadedApartmentAttribute { get; }
 
         string TestClassAttribute { get; }
+
+        bool SupportsReadonlyFields { get; }
     }
 }

src/Unitverse.Core/Frameworks/Test/BaseTestFramework.cs

@@ -23,6 +23,8 @@ protected BaseTestFramework(IUnitTestGeneratorOptions options)
 
         protected abstract string TestCaseAttributeName { get; }
 
+        public abstract bool SupportsReadonlyFields { get; }
+
         protected abstract BaseMethodDeclarationSyntax CreateSetupMethodSyntax(string targetTypeName);
 
         public IUnitTestGeneratorOptions Options { get; }

src/Unitverse.Core/Frameworks/Test/MsTestTestFramework.cs

@@ -30,6 +30,8 @@ public MsTestTestFramework(IUnitTestGeneratorOptions options)
 
         public bool SkipValueTypeNotNull => false;
 
+        public override bool SupportsReadonlyFields => false;
+
         public StatementSyntax AssertEqual(ExpressionSyntax actual, ExpressionSyntax expected, bool isReferenceType)
         {
             if (actual == null)

src/Unitverse.Core/Frameworks/Test/NUnitTestFramework.cs

@@ -30,6 +30,8 @@ protected NUnitTestFramework(IUnitTestGeneratorOptions options)
 
         public bool SkipValueTypeNotNull => false;
 
+        public override bool SupportsReadonlyFields => false;
+
         private static InvocationExpressionSyntax AssertThat => Generate.MemberInvocation("Assert", "That");
 
         public StatementSyntax AssertEqual(ExpressionSyntax actual, ExpressionSyntax expected, bool isReferenceType)

src/Unitverse.Core/Frameworks/Test/XUnitTestFramework.cs

@@ -30,6 +30,8 @@ public XUnitTestFramework(IUnitTestGeneratorOptions options)
 
         public bool SkipValueTypeNotNull => false;
 
+        public override bool SupportsReadonlyFields => true;
+
         public StatementSyntax AssertEqual(ExpressionSyntax actual, ExpressionSyntax expected, bool isReferenceType)
         {
             if (actual == null)

src/Unitverse.Core/Generation/TypeDeclarationFactory.cs

@@ -74,7 +74,7 @@ private static TypeDeclarationSyntax EnsureAllConstructorParametersHaveFields(IF
                     if (!autoFixtureFieldExists)
                     {
                         var defaultExpression = AutoFixtureHelper.GetCreationExpression(frameworkSet.Options.GenerationOptions);
-                        updatedMethod = UpdateMethod(updatedMethod, allFields, fields, autoFixtureFieldName, AutoFixtureHelper.TypeSyntax, defaultExpression);
+                        updatedMethod = UpdateMethod(updatedMethod, allFields, fields, autoFixtureFieldName, AutoFixtureHelper.TypeSyntax, defaultExpression, frameworkSet.TestFramework.SupportsReadonlyFields);
                     }
                 }
 
@@ -106,7 +106,7 @@ private static TypeDeclarationSyntax EnsureAllConstructorParametersHaveFields(IF
                             defaultExpression = AssignmentValueHelper.GetDefaultAssignmentValue(parameterModel.TypeInfo, classModel.SemanticModel, frameworkSet);
                         }
 
-                        updatedMethod = UpdateMethod(updatedMethod, allFields, fields, fieldName, fieldTypeSyntax, defaultExpression);
+                        updatedMethod = UpdateMethod(updatedMethod, allFields, fields, fieldName, fieldTypeSyntax, defaultExpression, frameworkSet.TestFramework.SupportsReadonlyFields);
                     }
                 }
 
@@ -137,12 +137,11 @@ private static TypeDeclarationSyntax EnsureAllConstructorParametersHaveFields(IF
             return targetType;
         }
 
-        private static BaseMethodDeclarationSyntax UpdateMethod(BaseMethodDeclarationSyntax updatedMethod, HashSet<string> allFields, List<FieldDeclarationSyntax> fields, string fieldName, TypeSyntax fieldTypeSyntax, ExpressionSyntax defaultExpression)
+        private static BaseMethodDeclarationSyntax UpdateMethod(BaseMethodDeclarationSyntax updatedMethod, HashSet<string> allFields, List<FieldDeclarationSyntax> fields, string fieldName, TypeSyntax fieldTypeSyntax, ExpressionSyntax defaultExpression, bool readonlyField)
         {
             var variable = SyntaxFactory.VariableDeclaration(fieldTypeSyntax)
                                         .AddVariables(SyntaxFactory.VariableDeclarator(fieldName));
-            var field = SyntaxFactory.FieldDeclaration(variable)
-                .AddModifiers(SyntaxFactory.Token(SyntaxKind.PrivateKeyword));
+            var field = Generate.Field(variable, readonlyField);
 
             fields.Add(field);
 

src/Unitverse.Core/Helpers/Generate.cs

@@ -462,11 +462,24 @@ public static SectionedMethodHandler SetupMethod(ClassModel model, string target
             return setupMethod;
         }
 
+        public static FieldDeclarationSyntax Field(VariableDeclarationSyntax variableDeclaration, bool readonlyField)
+        {
+            var field = SyntaxFactory.FieldDeclaration(variableDeclaration);
+
+            if (readonlyField)
+            {
+                return field.AddModifiers(SyntaxFactory.Token(SyntaxKind.PrivateKeyword), SyntaxFactory.Token(SyntaxKind.ReadOnlyKeyword));
+            }
+
+            return field.AddModifiers(SyntaxFactory.Token(SyntaxKind.PrivateKeyword));
+        }
+
         private static void AddConstructorField(ClassModel model, IFrameworkSet frameworkSet, ref ClassDeclarationSyntax classDeclaration, SectionedMethodHandler setupMethod, string fieldName, TypeInfo typeInfo)
         {
             var typeSyntax = typeInfo.ToTypeSyntax(frameworkSet.Context);
             ExpressionSyntax defaultExpression;
-            if (typeInfo.ShouldUseMock())
+            var isMock = typeInfo.ShouldUseMock();
+            if (isMock)
             {
                 typeSyntax = frameworkSet.MockingFramework.GetFieldType(typeSyntax);
                 frameworkSet.Context.InterfacesMocked++;
@@ -477,13 +490,13 @@ private static void AddConstructorField(ClassModel model, IFrameworkSet framewor
                 defaultExpression = AssignmentValueHelper.GetDefaultAssignmentValue(typeInfo, model.SemanticModel, frameworkSet);
             }
 
-            AddConstructorField(frameworkSet, ref classDeclaration, setupMethod, fieldName, typeSyntax, defaultExpression);
+            AddConstructorField(frameworkSet, ref classDeclaration, setupMethod, fieldName, typeSyntax, defaultExpression, isMock && frameworkSet.TestFramework.SupportsReadonlyFields);
         }
 
-        private static void AddConstructorField(IFrameworkSet frameworkSet, ref ClassDeclarationSyntax classDeclaration, SectionedMethodHandler setupMethod, string fieldName, TypeSyntax typeSyntax, ExpressionSyntax defaultExpression)
+        private static void AddConstructorField(IFrameworkSet frameworkSet, ref ClassDeclarationSyntax classDeclaration, SectionedMethodHandler setupMethod, string fieldName, TypeSyntax typeSyntax, ExpressionSyntax defaultExpression, bool readonlyField)
         {
             var variable = SyntaxFactory.VariableDeclaration(typeSyntax).AddVariables(SyntaxFactory.VariableDeclarator(fieldName));
-            var field = SyntaxFactory.FieldDeclaration(variable).AddModifiers(SyntaxFactory.Token(SyntaxKind.PrivateKeyword));
+            var field = Field(variable, readonlyField);
 
             classDeclaration = classDeclaration.AddMembers(field);
 

src/Unitverse.Core/Strategies/ClassGeneration/AbstractClassGenerationStrategy.cs

@@ -61,8 +61,7 @@ public ClassDeclarationSyntax Create(ClassModel model)
             var variableDeclaration = SyntaxFactory.VariableDeclaration(SyntaxFactory.ParseTypeName("Test" + model.ClassName))
                 .AddVariables(SyntaxFactory.VariableDeclarator(model.TargetFieldName));
 
-            var fieldDeclaration = SyntaxFactory.FieldDeclaration(variableDeclaration)
-                .AddModifiers(SyntaxFactory.Token(SyntaxKind.PrivateKeyword));
+            var fieldDeclaration = Generate.Field(variableDeclaration, _frameworkSet.TestFramework.SupportsReadonlyFields && model.TypeSymbol.IsReferenceType);
             classDeclaration = classDeclaration.AddMembers(fieldDeclaration);
 
             if (_frameworkSet.Options.GenerationOptions.UseFieldForAutoFixture)

src/Unitverse.Core/Strategies/ClassGeneration/StandardClassGenerationStrategy.cs

@@ -58,8 +58,7 @@ public ClassDeclarationSyntax Create(ClassModel model)
             var variableDeclaration = SyntaxFactory.VariableDeclaration(model.TypeSyntax)
                 .AddVariables(SyntaxFactory.VariableDeclarator(model.TargetFieldName));
 
-            var fieldDeclaration = SyntaxFactory.FieldDeclaration(variableDeclaration)
-                .AddModifiers(SyntaxFactory.Token(SyntaxKind.PrivateKeyword));
+            var fieldDeclaration = Generate.Field(variableDeclaration, _frameworkSet.TestFramework.SupportsReadonlyFields && model.TypeSymbol.IsReferenceType);
             classDeclaration = classDeclaration.AddMembers(fieldDeclaration);
 
             if (_frameworkSet.Options.GenerationOptions.UseFieldForAutoFixture)