Added a connection pool (#11)

L

tests/postgres/test_write_and_read_pool.cpp

@@ -0,0 +1,57 @@
+#ifndef SQLGEN_BUILD_DRY_TESTS_ONLY
+
+#include <gtest/gtest.h>
+
+#include <rfl.hpp>
+#include <rfl/json.hpp>
+#include <sqlgen.hpp>
+#include <sqlgen/postgres.hpp>
+#include <vector>
+
+namespace test_write_and_read_pool {
+
+struct Person {
+  sqlgen::PrimaryKey<uint32_t> id;
+  std::string first_name;
+  std::string last_name;
+  int age;
+};
+
+TEST(postgres, test_write_and_read_pool) {
+  const auto people1 = std::vector<Person>(
+      {Person{
+           .id = 0, .first_name = "Homer", .last_name = "Simpson", .age = 45},
+       Person{.id = 1, .first_name = "Bart", .last_name = "Simpson", .age = 10},
+       Person{.id = 2, .first_name = "Lisa", .last_name = "Simpson", .age = 8},
+       Person{
+           .id = 3, .first_name = "Maggie", .last_name = "Simpson", .age = 0}});
+
+  const auto pool_config = sqlgen::ConnectionPoolConfig{.size = 2};
+
+  const auto credentials = sqlgen::postgres::Credentials{.user = "postgres",
+                                                         .password = "password",
+                                                         .host = "localhost",
+                                                         .dbname = "postgres"};
+
+  const auto pool = sqlgen::make_connection_pool<sqlgen::postgres::Connection>(
+      pool_config, credentials);
+
+  using namespace sqlgen;
+
+  const auto people2 = session(pool)
+                           .and_then(drop<Person> | if_exists)
+                           .and_then(write(std::ref(people1)))
+                           .and_then(sqlgen::read<std::vector<Person>>)
+                           .value();
+
+  EXPECT_EQ(pool.value().available(), 2);
+
+  const auto json1 = rfl::json::write(people1);
+  const auto json2 = rfl::json::write(people2);
+
+  EXPECT_EQ(json1, json2);
+}
+
+}  // namespace test_write_and_read_pool
+
+#endif