[efficiency-improver] perf: avoid string[1] allocation in Condition.Evaluate for single-string properties

src/Microsoft.TestPlatform.Filter.Source/Condition.cs

@@ -157,8 +157,32 @@ internal bool Evaluate(Func<string, object?> propertyValueProvider)
 #if IS_VSTEST_REPO
         ValidateArg.NotNull(propertyValueProvider, nameof(propertyValueProvider));
 #endif
-        var multiValue = GetPropertyValue(propertyValueProvider);
-        var result = Operation switch
+        var propertyValue = propertyValueProvider(Name);
+
+        // Fast path: single string value (most common case for FullyQualifiedName, DisplayName, etc.)
+        // Avoids allocating a string[1] wrapper that the general multi-value path would create.
+        if (propertyValue is string singleValue)
+        {
+            return Operation switch
+            {
+                Operation.Equal => string.Equals(singleValue, Value, StringComparison.OrdinalIgnoreCase),
+                Operation.NotEqual => !string.Equals(singleValue, Value, StringComparison.OrdinalIgnoreCase),
+                Operation.Contains => singleValue.IndexOf(Value, StringComparison.OrdinalIgnoreCase) != -1,
+                Operation.NotContains => singleValue.IndexOf(Value, StringComparison.OrdinalIgnoreCase) == -1,
+                _ => false,
+            };
+        }
+
+        // Null, string[], or other types: use multi-value evaluation.
+        // Other types are coerced via ToString() for backward compatibility.
+        string[]? multiValue = propertyValue switch
+        {
+            null => null,
+            string[] arr => arr,
+            _ => new[] { propertyValue.ToString()! },
+        };
+
+        return Operation switch
         {
             // if any value in multi-valued property matches 'this.Value', for Equal to evaluate true.
             Operation.Equal => EvaluateEqualOperation(multiValue),
@@ -170,8 +194,6 @@ internal bool Evaluate(Func<string, object?> propertyValueProvider)
             Operation.NotContains => !EvaluateContainsOperation(multiValue),
             _ => false,
         };
-
-        return result;
     }
 
     /// <summary>
@@ -292,25 +314,6 @@ private static Operation GetOperator(string operationString)
         };
     }
 
-    /// <summary>
-    /// Returns property value for Property using propertValueProvider.
-    /// </summary>
-    private string[]? GetPropertyValue(Func<string, object?> propertyValueProvider)
-    {
-        var propertyValue = propertyValueProvider(Name);
-        if (null != propertyValue)
-        {
-            if (propertyValue is not string[] multiValue)
-            {
-                multiValue = new string[1];
-                multiValue[0] = propertyValue.ToString()!;
-            }
-            return multiValue;
-        }
-
-        return null;
-    }
-
     internal static IEnumerable<string> TokenizeFilterConditionString(string str)
     {
         return str == null ? throw new ArgumentNullException(nameof(str)) : TokenizeFilterConditionStringWorker(str);