fluentassertions · jnyrup · Dec 17, 2025 · Dec 16, 2025 · Dec 16, 2025 · Dec 16, 2025
diff --git a/Src/FluentAssertions/Equivalency/Field.cs b/Src/FluentAssertions/Equivalency/Field.cs
@@ -18,7 +18,7 @@ public Field(FieldInfo fieldInfo, INode parent)
        this.fieldInfo = fieldInfo;
        DeclaringType = fieldInfo.DeclaringType;
        ReflectedType = fieldInfo.ReflectedType;
-        Subject = new Pathway(parent.Subject.PathAndName, fieldInfo.Name,  pathAndName => $"field {parent.GetSubjectId().Combine(pathAndName)}");
+        Subject = new Pathway(parent.Subject.PathAndName, fieldInfo.Name, pathAndName => $"field {parent.GetSubjectId().Combine(pathAndName)}");
        Expectation = new Pathway(parent.Expectation.PathAndName, fieldInfo.Name, pathAndName => $"field {pathAndName}");
        GetSubjectId = parent.GetSubjectId;
        Type = fieldInfo.FieldType;
@@ -33,7 +33,7 @@ public object GetValue(object obj)
        return fieldInfo.GetValue(obj);
    }

-    public Type DeclaringType { get; set; }
+    public Type DeclaringType { get; }

    public CSharpAccessModifier GetterAccessibility => fieldInfo.GetCSharpAccessModifier();


diff --git a/Src/FluentAssertions/Equivalency/INode.cs b/Src/FluentAssertions/Equivalency/INode.cs
@@ -30,7 +30,7 @@ public interface INode
    /// <summary>
    /// Gets the path from the root of the subject upto and including the current node.
    /// </summary>
-    Pathway Subject { get; internal set; }
+    Pathway Subject { get; }

    /// <summary>
    /// Gets the path from the root of the expectation upto and including the current node.

diff --git a/Src/FluentAssertions/Equivalency/Node.cs b/Src/FluentAssertions/Equivalency/Node.cs
@@ -18,14 +18,14 @@ public GetSubjectId GetSubjectId
        protected init => field = value;
    }

-    public Type Type { get; protected set; }
+    public Type Type { get; init; }

-    public Type ParentType { get; protected set; }
+    public Type ParentType { get; init; }

    public Pathway Subject
    {
        get;
-        set
+        protected set
        {
            field = value;
            Expectation ??= value;
@@ -46,7 +46,7 @@ public bool IsRoot

    private bool IsFirstIndex => MatchFirstIndex.IsMatch(Subject.PathAndName);

-    public bool RootIsCollection { get; protected set; }
+    public bool RootIsCollection { get; init; }

    public void AdjustForRemappedSubject(IMember subjectMember)
    {

diff --git a/Src/FluentAssertions/Equivalency/Property.cs b/Src/FluentAssertions/Equivalency/Property.cs
@@ -24,7 +24,7 @@ public Property(Type reflectedType, PropertyInfo propertyInfo, INode parent)
        ReflectedType = reflectedType;
        this.propertyInfo = propertyInfo;
        DeclaringType = propertyInfo.DeclaringType;
-        Subject = new Pathway(parent.Subject.PathAndName, propertyInfo.Name,  pathAndName => $"property {parent.GetSubjectId().Combine(pathAndName)}");
+        Subject = new Pathway(parent.Subject.PathAndName, propertyInfo.Name, pathAndName => $"property {parent.GetSubjectId().Combine(pathAndName)}");
        Expectation = new Pathway(parent.Expectation.PathAndName, propertyInfo.Name, pathAndName => $"property {pathAndName}");
        Type = propertyInfo.PropertyType;
        ParentType = propertyInfo.DeclaringType;
@@ -45,14 +45,6 @@ public object GetValue(object obj)

    public CSharpAccessModifier SetterAccessibility => propertyInfo.GetSetMethod(nonPublic: true).GetCSharpAccessModifier();

-    public bool IsBrowsable
-    {
-        get
-        {
-            isBrowsable ??=
-                propertyInfo.GetCustomAttribute<EditorBrowsableAttribute>() is not { State: EditorBrowsableState.Never };
-
-            return isBrowsable.Value;
-        }
-    }
+    public bool IsBrowsable =>
+        isBrowsable ??= propertyInfo.GetCustomAttribute<EditorBrowsableAttribute>() is not { State: EditorBrowsableState.Never };
 }
diff --git a/Src/FluentAssertions/Equivalency/Steps/EnumerableEquivalencyValidator.cs b/Src/FluentAssertions/Equivalency/Steps/EnumerableEquivalencyValidator.cs
@@ -31,12 +31,11 @@ public EnumerableEquivalencyValidator(AssertionChain assertionChain, IValidateCh
        this.assertionChain = assertionChain;
        this.parent = parent;
        this.context = context;
-        Recursive = false;
    }

-    public bool Recursive { get; init; }
+    public required bool Recursive { get; init; }

-    public OrderingRuleCollection OrderingRules { get; init; }
+    public required OrderingRuleCollection OrderingRules { get; init; }

    public void Execute<T>(object[] subject, T[] expectation)
    {

diff --git a/Src/FluentAssertions/Equivalency/Steps/EqualityComparerEquivalencyStep.cs b/Src/FluentAssertions/Equivalency/Steps/EqualityComparerEquivalencyStep.cs
@@ -1,5 +1,5 @@
-using System;
 using System.Collections.Generic;
+using FluentAssertions.Common;
 using FluentAssertions.Execution;

 namespace FluentAssertions.Equivalency.Steps;
@@ -10,7 +10,8 @@ public class EqualityComparerEquivalencyStep<T> : IEquivalencyStep

    public EqualityComparerEquivalencyStep(IEqualityComparer<T> comparer)
    {
-        this.comparer = comparer ?? throw new ArgumentNullException(nameof(comparer));
+        Guard.ThrowIfArgumentIsNull(comparer);
+        this.comparer = comparer;
    }

    public EquivalencyResult Handle(Comparands comparands, IEquivalencyValidationContext context,

diff --git a/Src/FluentAssertions/Equivalency/Tracing/InternalTraceWriter.cs b/Src/FluentAssertions/Equivalency/Tracing/InternalTraceWriter.cs
@@ -1,5 +1,3 @@
 namespace FluentAssertions.Equivalency.Tracing;

-internal sealed class InternalTraceWriter : StringBuilderTraceWriter
-{
-}
+internal sealed class InternalTraceWriter : StringBuilderTraceWriter;
diff --git a/Src/FluentAssertions/Execution/AssertionScope.cs b/Src/FluentAssertions/Execution/AssertionScope.cs
@@ -69,11 +69,11 @@ public AssertionScope(Func<string> name)
    /// <exception cref="ArgumentNullException"><paramref name="assertionStrategy"/> is <see langword="null"/>.</exception>
    private AssertionScope(Func<string> name, IAssertionStrategy assertionStrategy)
    {
+        Guard.ThrowIfArgumentIsNull(assertionStrategy);
        parent = CurrentScope.Value;
        CurrentScope.Value = this;

-        this.assertionStrategy = assertionStrategy
-                                 ?? throw new ArgumentNullException(nameof(assertionStrategy));
+        this.assertionStrategy = assertionStrategy;

        if (parent is not null)
        {

diff --git a/Src/FluentAssertions/Primitives/DateTimeOffsetAssertions.cs b/Src/FluentAssertions/Primitives/DateTimeOffsetAssertions.cs
@@ -263,8 +263,7 @@ public AndConstraint<TAssertions> NotBeExactly(DateTimeOffset? unexpected,
        [StringSyntax("CompositeFormat")] string because = "", params object[] becauseArgs)
    {
        assertionChain
-            .ForCondition(!((Subject == null && unexpected == null) ||
-                (Subject != null && unexpected != null && Subject.Value.EqualsExact(unexpected.Value))))
+            .ForCondition(!(Subject.HasValue == unexpected.HasValue && Subject.GetValueOrDefault().EqualsExact(unexpected.GetValueOrDefault())))
            .BecauseOf(because, becauseArgs)
            .FailWith("Did not expect {context:the date and time} to be exactly {0}{reason}, but it was.", unexpected);


diff --git a/Src/FluentAssertions/Primitives/SimpleTimeSpanAssertions.cs b/Src/FluentAssertions/Primitives/SimpleTimeSpanAssertions.cs
@@ -249,7 +249,7 @@ public AndConstraint<TAssertions> BeCloseTo(TimeSpan nearbyTime, TimeSpan precis
        TimeSpan maximumValue = nearbyTime + precision;

        assertionChain
-            .ForCondition(Subject >= minimumValue && Subject.Value <= maximumValue)
+            .ForCondition(Subject >= minimumValue && Subject <= maximumValue)
            .BecauseOf(because, becauseArgs)
            .FailWith("Expected {context:time} to be within {0} from {1}{reason}, but found {2}.",
                precision,

diff --git a/Src/FluentAssertions/Primitives/StringEqualityStrategy.cs b/Src/FluentAssertions/Primitives/StringEqualityStrategy.cs
@@ -23,7 +23,7 @@ public StringEqualityStrategy(IEqualityComparer<string> comparer, string predica
    /// Gets a value indicating whether the differences between string properties should
    /// include the full values of the subject and expectation instead of just the fragment that differs.
    /// </summary>
-    public bool IncludeFullDetails { get; set; } = true;
+    public bool IncludeFullDetails { get; init; } = true;

    public void AssertForEquality(AssertionChain assertionChain, string subject, string expected)
    {

diff --git a/Src/FluentAssertions/Specialized/DelegateAssertionsBase.cs b/Src/FluentAssertions/Specialized/DelegateAssertionsBase.cs
@@ -26,9 +26,11 @@ private protected DelegateAssertionsBase(TDelegate @delegate, IExtractExceptions
        IClock clock)
        : base(@delegate, assertionChain)
    {
+        Guard.ThrowIfArgumentIsNull(extractor);
+        Guard.ThrowIfArgumentIsNull(clock);
        this.assertionChain = assertionChain;
-        Extractor = extractor ?? throw new ArgumentNullException(nameof(extractor));
-        Clock = clock ?? throw new ArgumentNullException(nameof(clock));
+        Extractor = extractor;
+        Clock = clock;
    }

    private protected IClock Clock { get; }

diff --git a/Src/FluentAssertions/Specialized/ExecutionTimeAssertions.cs b/Src/FluentAssertions/Specialized/ExecutionTimeAssertions.cs
@@ -21,7 +21,8 @@ public class ExecutionTimeAssertions
    /// <param name="executionTime">The execution on which time must be asserted.</param>
    public ExecutionTimeAssertions(ExecutionTime executionTime, AssertionChain assertionChain)
    {
-        execution = executionTime ?? throw new ArgumentNullException(nameof(executionTime));
+        Guard.ThrowIfArgumentIsNull(executionTime);
+        execution = executionTime;
        this.assertionChain = assertionChain;
    }


diff --git a/Src/FluentAssertions/Specialized/TaskCompletionSourceAssertionsBase.cs b/Src/FluentAssertions/Specialized/TaskCompletionSourceAssertionsBase.cs
@@ -14,7 +14,8 @@ public class TaskCompletionSourceAssertionsBase
 {
    protected TaskCompletionSourceAssertionsBase(IClock clock)
    {
-        Clock = clock ?? throw new ArgumentNullException(nameof(clock));
+        Guard.ThrowIfArgumentIsNull(clock);
+        Clock = clock;
    }

    private protected IClock Clock { get; }