Add TAP test for select @@version without backend

Signed-off-by: Wazir Ahmed <wazir@proxysql.com>

test/tap/tests/mysql-select_version_without_backend-t.cpp

@@ -0,0 +1,95 @@
+/**
+ * @file mysql-select_version_without_backend-t.cpp
+ * @brief This TAP test validates if SELECT VERSION() works without making calls to the backend.
+ */
+
+#include <unistd.h>
+#include <string>
+
+#include "mysql.h"
+
+#include "tap.h"
+#include "command_line.h"
+#include "utils.h"
+
+using std::string;
+
+#define MYSQL_TEST_SERVER_VERSION "8.4.6"
+#define MYSQL_SET_SERVER_VERSION_QUERY "SET mysql-server_version='" MYSQL_TEST_SERVER_VERSION "'"
+
+MYSQL* init_mysql_conn(char* host, char* user, char* pass, int port) {
+	diag("Creating MySQL conn host=\"%s\" port=\"%d\" user=\"%s\"", host, port, user);
+
+	MYSQL* mysql = mysql_init(NULL);
+	if (!mysql) {
+		return nullptr;
+	}
+
+	if (!mysql_real_connect(mysql, host, user, pass, NULL, port, NULL, 0)) {
+		return nullptr;
+	}
+
+	return mysql;
+}
+
+int run_q(MYSQL *mysql, const char *q) {
+	MYSQL_QUERY_T(mysql,q);
+	return 0;
+}
+
+int main(int argc, char** argv) {
+	plan(2);
+
+	CommandLine cl;
+	if (cl.getEnv()) {
+		diag("Failed to get the required environmental variables.");
+		return exit_status();
+	}
+
+	MYSQL* admin = init_mysql_conn(cl.host, cl.admin_username, cl.admin_password, cl.admin_port);
+	if (!admin) {
+		fprintf(stderr, "File %s, line %d, Error: %s\n", __FILE__, __LINE__, mysql_error(admin));
+		return exit_status();
+	}
+
+	MYSQL_QUERY_T(admin, MYSQL_SET_SERVER_VERSION_QUERY);
+	MYSQL_QUERY_T(admin, "LOAD MYSQL VARIABLES TO RUNTIME");
+
+	MYSQL_QUERY_T(admin, "DELETE FROM mysql_servers");
+	MYSQL_QUERY_T(admin, "LOAD MYSQL SERVERS TO RUNTIME");
+
+	MYSQL* proxy = init_mysql_conn(cl.host, cl.username, cl.password, cl.port);
+	if (!proxy) {
+		fprintf(stderr, "File %s, line %d, Error: %s\n", __FILE__, __LINE__, mysql_error(proxy));
+		return exit_status();
+	}
+
+	const char *version_get_queries[2] = {
+		"SELECT @@VERSION",
+		"SELECT VERSION()"
+	};
+
+	for (int i = 0; i < 2; i++) {
+		MYSQL_ROW row = nullptr;
+		string res_server_version;
+
+		int rc = run_q(proxy, version_get_queries[i]);
+		if (rc == 0) {
+			MYSQL_RES* proxy_res = mysql_store_result(proxy);
+
+			row = mysql_fetch_row(proxy_res);
+			if (row) {
+				res_server_version = row[0];
+			}
+
+			mysql_free_result(proxy_res);
+		}
+
+		ok(row && (res_server_version == MYSQL_TEST_SERVER_VERSION), "Server version: %s", res_server_version.c_str());
+	}
+
+	mysql_close(admin);
+	mysql_close(proxy);
+
+	return exit_status();
+}