Added a test for string views (#223)

Author: liuzicheng1987

tests/json/test_string_view.cpp

@@ -0,0 +1,28 @@
+#include <gtest/gtest.h>
+
+#include <functional>
+#include <iostream>
+#include <rfl.hpp>
+#include <rfl/json.hpp>
+#include <string_view>
+
+namespace test_string_view {
+
+struct TestStruct {
+  std::string_view name;
+};
+
+TEST(json, test_string_view) {
+  const std::string name = "Homer Simpson";
+  const auto test_struct = TestStruct{.name = name};
+
+  const auto json_string = rfl::json::write(test_struct);
+  const std::string expected = R"({"name":"Homer Simpson"})";
+  EXPECT_EQ(json_string, expected)
+      << "Test failed on write. Expected:" << std::endl
+      << expected << std::endl
+      << "Got: " << std::endl
+      << json_string << std::endl
+      << std::endl;
+}
+}  // namespace test_string_view