fix: skip tests marked with an empty skip reason

src/TUnit.Core/Attributes/TestMetadata/SkipAttribute.cs

@@ -39,6 +39,17 @@ namespace TUnit.Core;
 [AttributeUsage(AttributeTargets.Method | AttributeTargets.Class | AttributeTargets.Assembly, AllowMultiple = true)]
 public class SkipAttribute : Attribute, ITestRegisteredEventReceiver
 {
+    /// <summary>
+    /// The skip reason reported when a skip is requested with a null or empty reason.
+    /// The engine treats an empty skip reason as "not skipped", so it must never be stored as-is.
+    /// </summary>
+    internal const string DefaultReason = "No reason provided";
+
+    /// <summary>
+    /// Returns <paramref name="reason"/>, or <see cref="DefaultReason"/> when it is null or empty.
+    /// </summary>
+    internal static string NormalizeReason(string? reason) => string.IsNullOrEmpty(reason) ? DefaultReason : reason!;
+
     public string Reason { get; }
 
     public SkipAttribute(string reason)

src/TUnit.Core/Contexts/TestRegisteredContext.cs

@@ -105,7 +105,8 @@ internal void SetExplicitParallelLimiter(IParallelLimit parallelLimit)
     /// <param name="reason">The reason why the test is being skipped</param>
     public void SetSkipped(string reason)
     {
-        TestContext.SkipReason = reason;
+        // An empty reason would otherwise read as "not skipped" (#7077).
+        TestContext.SkipReason = SkipAttribute.NormalizeReason(reason);
         TestContext.Metadata.TestDetails.ClassInstance = SkippedTestInstance.Instance;
     }
 

src/TUnit.Engine/Building/TestBuilder.cs

@@ -1206,8 +1206,9 @@ private static void CollectAllDependencies(AbstractExecutableTest test, HashSet<
         }
 
         // All skip attributes are basic SkipAttribute instances
-        // Return the first reason (they all should skip), or null if no skip attributes
-        return firstSkipAttribute?.Reason;
+        // Return the first reason (they all should skip), or null if no skip attributes.
+        // An empty reason is normalized, because empty means "custom skip attribute" here (#7077).
+        return firstSkipAttribute is null ? null : SkipAttribute.NormalizeReason(firstSkipAttribute.Reason);
     }
 
     private async ValueTask<TestContext> CreateTestContextAsync(string testId, TestMetadata metadata, TestData testData, TestBuilderContext testBuilderContext, CancellationToken cancellationToken = default)

tests/TUnit.Engine.Tests/Issue7077Tests.cs

@@ -0,0 +1,35 @@
+using Shouldly;
+using TUnit.Engine.Tests.Enums;
+
+namespace TUnit.Engine.Tests;
+
+public class Issue7077Tests(TestMode testMode) : InvokableTestBase(testMode)
+{
+    [Test]
+    public async Task Skip_With_Empty_Or_Null_Reason_Skips_The_Test()
+    {
+        await RunTestsWithFilter(
+            "/*/TUnit.TestProject.Bugs._7077/EmptySkipReasonTests/*",
+            [
+                result => result.ResultSummary.Outcome.ShouldBe("Completed"),
+                result => result.ResultSummary.Counters.Total.ShouldBe(4),
+                result => result.ResultSummary.Counters.Passed.ShouldBe(0),
+                result => result.ResultSummary.Counters.Failed.ShouldBe(0),
+                result => result.ResultSummary.Counters.NotExecuted.ShouldBe(4)
+            ]);
+    }
+
+    [Test]
+    public async Task Class_Level_Skip_With_Empty_Reason_Skips_Without_Constructing()
+    {
+        await RunTestsWithFilter(
+            "/*/TUnit.TestProject.Bugs._7077/EmptySkipReasonClassTests/*",
+            [
+                result => result.ResultSummary.Outcome.ShouldBe("Completed"),
+                result => result.ResultSummary.Counters.Total.ShouldBe(1),
+                result => result.ResultSummary.Counters.Passed.ShouldBe(0),
+                result => result.ResultSummary.Counters.Failed.ShouldBe(0),
+                result => result.ResultSummary.Counters.NotExecuted.ShouldBe(1)
+            ]);
+    }
+}

tests/TUnit.TestProject/Bugs/_7077/EmptySkipReasonTests.cs

@@ -0,0 +1,38 @@
+using TUnit.TestProject.Attributes;
+
+namespace TUnit.TestProject.Bugs._7077;
+
+[EngineTest(ExpectedResult.Pass)]
+public class EmptySkipReasonTests
+{
+    [Test, Skip("")]
+    public void EmptyReason_IsSkipped() => throw new Exception("test ran");
+
+    [Test, Skip(null!)]
+    public void NullReason_IsSkipped() => throw new Exception("test ran");
+
+    [Test, Skip("reason")]
+    public void NonEmptyReason_IsSkipped() => throw new Exception("control ran");
+
+    [Test, EmptyReasonSkip]
+    public void DerivedAttributeWithEmptyReason_IsSkipped() => throw new Exception("test ran");
+}
+
+[EngineTest(ExpectedResult.Pass)]
+[Skip("")]
+public class EmptySkipReasonClassTests
+{
+    public EmptySkipReasonClassTests() => throw new Exception("constructor ran");
+
+    [Test]
+    public void ClassLevelEmptyReason_IsSkipped() => throw new Exception("test ran");
+}
+
+/// <summary>
+/// A derived skip attribute is evaluated at registration time rather than discovery time,
+/// so it exercises the runtime skip path with an empty reason.
+/// </summary>
+public class EmptyReasonSkipAttribute() : SkipAttribute("")
+{
+    public override Task<bool> ShouldSkip(TestRegisteredContext context) => Task.FromResult(true);
+}