Add converter tests with throw_on_error

test/test_helpers.hpp

@@ -79,3 +79,13 @@ struct buffer {
     }
 
 #define CHECK_NOT_VARIANT(var, type) CHECK(!std::holds_alternative<type>(var));
+// TODO remove
+#include <iostream>
+
+#define REQUIRE_EXCEPTION(...)                                                 \
+    try {                                                                      \
+        __VA_ARGS__;                                                           \
+        FAIL("Expected exception");                                            \
+    } catch (ss::exception & e) {                                              \
+        CHECK_FALSE(std::string{e.what()}.empty());                            \
+    }