Fix method overload issue with params when the last parameter is empy

Author: JonathanMagnan

Z.Dynamic.Core.Lab/Request_DynamicLinqType.cs

@@ -25,6 +25,16 @@ public static string[] ConvertToArray(params string[] values)
 
                 return values.ToArray();
             }
+
+            public static string[] ConvertToArray(int a, params string[] values)
+            {
+                if (values == null)
+                {
+                    return null;
+                }
+
+                return values.ToArray();
+            }
         }
 
         public static void Execute()
@@ -38,7 +48,7 @@ public static void Execute()
 
             var t1 = Utils.ConvertToArray(null);
 
-            string query = "Utils.ConvertToArray(null)";
+            string query = "Utils.ConvertToArray()";
             LambdaExpression expression = DynamicExpressionParser.ParseLambda(null, query, externals);
             Delegate del = expression.Compile();
             var result = del.DynamicInvoke();

src/System.Linq.Dynamic.Core/Parser/SupportedMethods/MethodFinder.cs

@@ -113,9 +113,12 @@ public int FindIndexer(Type type, Expression[] args, out MethodBase method)
 
         bool IsApplicable(MethodData method, Expression[] args)
         {
-            // parameter count must be equal or the last one must be a param array
             bool isParamArray = method.Parameters.Length > 0 && method.Parameters.Last().IsDefined(typeof(ParamArrayAttribute), false);
-            if (method.Parameters.Length != args.Length && !isParamArray)
+
+            // if !paramArray, the number of parameter must be equal
+            // if paramArray, the last parameter is optional
+            if ((!isParamArray && method.Parameters.Length != args.Length) ||
+                (isParamArray && method.Parameters.Length - 1 > args.Length))
             {
                 return false;
             }

test/System.Linq.Dynamic.Core.Tests/Parser/DynamicLinqTypeTest.cs

@@ -18,6 +18,16 @@ public static string[] ConvertToArray(params string[] values)
 
                 return values.ToArray();
             }
+
+            public static string[] ConvertToArray(int a, params string[] values)
+            {
+                if (values == null)
+                {
+                    return null;
+                }
+
+                return values.ToArray();
+            }
         }
 
 
@@ -67,5 +77,41 @@ public void ParamArray_WithSingleValue()
             Check.That(result.Length).Equals(1);
             Check.That(result[0]).Equals("a");
         }
+
+        [Fact]
+        public void ParamArray_NullValue2()
+        {
+            var query = "Utils.ConvertToArray(0, null)";
+            var expression = DynamicExpressionParser.ParseLambda(null, query, null);
+            var del = expression.Compile();
+            var result = (string[])del.DynamicInvoke();
+
+            Check.That(result).IsNull();
+        }
+
+        [Fact]
+        public void ParamArray_WithManyValue2()
+        {
+            var query = "Utils.ConvertToArray(0, \"a\", \"b\")";
+            var expression = DynamicExpressionParser.ParseLambda(null, query, null);
+            var del = expression.Compile();
+            var result = (string[])del.DynamicInvoke();
+
+            Check.That(result.Length).Equals(2);
+            Check.That(result[0]).Equals("a");
+            Check.That(result[1]).Equals("b");
+        }
+
+        [Fact]
+        public void ParamArray_WithSingleValue2()
+        {
+            var query = "Utils.ConvertToArray(0, \"a\")";
+            var expression = DynamicExpressionParser.ParseLambda(null, query, null);
+            var del = expression.Compile();
+            var result = (string[])del.DynamicInvoke();
+
+            Check.That(result.Length).Equals(1);
+            Check.That(result[0]).Equals("a");
+        }
     }
 }