Added tests for postgres

tests/postgres/test_timestamp.cpp

@@ -0,0 +1,47 @@
+#ifndef SQLGEN_BUILD_DRY_TESTS_ONLY
+
+#include <gtest/gtest.h>
+
+#include <rfl/json.hpp>
+#include <sqlgen.hpp>
+#include <sqlgen/postgres.hpp>
+
+namespace test_timestamp {
+
+struct Person {
+  sqlgen::PrimaryKey<uint32_t> id;
+  std::string first_name;
+  std::string last_name;
+  sqlgen::Timestamp<"%Y-%m-%d %H:%M:%S"> ts;
+};
+
+TEST(postgres, test_timestamp) {
+  const auto people1 =
+      std::vector<Person>({Person{.id = 0,
+                                  .first_name = "Homer",
+                                  .last_name = "Simpson",
+                                  .ts = "2000-01-01 01:00:00"}});
+
+  using namespace sqlgen;
+
+  const auto credentials = sqlgen::postgres::Credentials{.user = "postgres",
+                                                         .password = "password",
+                                                         .host = "localhost",
+                                                         .dbname = "postgres"};
+
+  const auto conn =
+      sqlgen::postgres::connect(credentials).and_then(drop<Person> | if_exists);
+
+  const auto people2 = sqlgen::write(conn, people1)
+                           .and_then(sqlgen::read<std::vector<Person>>)
+                           .value();
+
+  const auto json1 = rfl::json::write(people1);
+  const auto json2 = rfl::json::write(people2);
+
+  EXPECT_EQ(json1, json2);
+}
+
+}  // namespace test_timestamp
+
+#endif