Added documentation for the timestamps

tests/postgres/test_timestamp_dry.cpp

@@ -0,0 +1,23 @@
+#include <gtest/gtest.h>
+
+#include <sqlgen.hpp>
+#include <sqlgen/postgres.hpp>
+
+namespace test_timestamp_dry {
+
+struct TestTable {
+  std::string field1;
+  int32_t field2;
+  sqlgen::PrimaryKey<uint32_t> id;
+  sqlgen::Timestamp<"%Y-%m-%d %H:%M:%S"> ts;
+};
+
+TEST(postgres, test_timestamp_dry) {
+  const auto query = sqlgen::CreateTable<TestTable>{};
+
+  const auto expected =
+      R"(CREATE TABLE IF NOT EXISTS "TestTable" ("field1" TEXT NOT NULL, "field2" INTEGER NOT NULL, "id" INTEGER NOT NULL, "ts" TIMESTAMP NOT NULL, PRIMARY KEY ("id"));)";
+
+  EXPECT_EQ(sqlgen::postgres::to_sql(query), expected);
+}
+}  // namespace test_timestamp_dry

tests/postgres/test_timestamp_with_tz_dry.cpp

@@ -0,0 +1,23 @@
+#include <gtest/gtest.h>
+
+#include <sqlgen.hpp>
+#include <sqlgen/postgres.hpp>
+
+namespace test_timestamp_with_tz_dry {
+
+struct TestTable {
+  std::string field1;
+  int32_t field2;
+  sqlgen::PrimaryKey<uint32_t> id;
+  sqlgen::Timestamp<"%Y-%m-%d %H:%M:%S%z"> ts;
+};
+
+TEST(postgres, test_timestamp_with_tz_dry) {
+  const auto query = sqlgen::CreateTable<TestTable>{};
+
+  const auto expected =
+      R"(CREATE TABLE IF NOT EXISTS "TestTable" ("field1" TEXT NOT NULL, "field2" INTEGER NOT NULL, "id" INTEGER NOT NULL, "ts" TIMESTAMP WITH TIME ZONE NOT NULL, PRIMARY KEY ("id"));)";
+
+  EXPECT_EQ(sqlgen::postgres::to_sql(query), expected);
+}
+}  // namespace test_timestamp_with_tz_dry