jinja: fix macro with kwargs (#20960)

* jinja: fix macro with kwargs

* Apply suggestions from code review

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

* fix newline problem

---------

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

tests/test-jinja.cpp

@@ -884,6 +884,24 @@ static void test_macros(testing & t) {
         json::object(),
         "Hi Guest"
     );
+
+    test_template(t, "macro kwargs input",
+        "{% macro my_func(a, b=False) %}{% if b %}{{ a }}{% else %}nope{% endif %}{% endmacro %}{{ my_func(1, b=True) }}",
+        json::object(),
+        "1"
+    );
+
+    test_template(t, "macro with multiple args",
+        "{% macro add(a, b, c=0) %}{{ a + b + c }}{% endmacro %}{{ add(1, 2) }},{{ add(1, 2, 3) }},{{ add(1, b=10) }},{{ add(1, 2, c=5) }}",
+        json::object(),
+        "3,6,11,8"
+    );
+
+    test_template(t, "macro with kwarg out-of-order input",
+        "{% macro greet(first, last, greeting='Hello') %}{{ greeting }}, {{ first }} {{ last }}{% endmacro %}{{ greet(last='Smith', first='John') }},{{ greet(last='Doe', greeting='Hi', first='Jane') }}",
+        json::object(),
+        "Hello, John Smith,Hi, Jane Doe"
+    );
 }
 
 static void test_namespace(testing & t) {