Add a test plan skip message to commons

Allure.Net.Commons/TestPlan/AllureTestPlan.cs

@@ -86,7 +86,10 @@ public static AllureTestPlan FromEnvironment()
     /// </summary>
     public static readonly AllureTestPlan DEFAULT_TESTPLAN = new();
 
-    static string? ResolveTestPlanPath() =>
+    /// <summary>
+    /// Returns the path of the current test plan file, if any.
+    /// </summary>
+    public static string? ResolveTestPlanPath() =>
         new[]
         {
             AllureConstants.NEW_ALLURE_TESTPLAN_ENV_NAME,
@@ -95,6 +98,13 @@ public static AllureTestPlan FromEnvironment()
             ev => !string.IsNullOrWhiteSpace(ev)
         ).FirstOrDefault();
 
+    /// <summary>
+    /// A short message that can be used to report an ignored test to the test
+    /// framework.
+    /// </summary>
+    public static string SkipReason =>
+        "Not in the test plan " + (ResolveTestPlanPath() ?? "");
+
     static AllureTestPlan GetTestPlanByPath(string? testPlanPath) =>
         testPlanPath is null || !File.Exists(testPlanPath)
             ? DEFAULT_TESTPLAN