test: Add comprehensive wait_timeout JSON validation tests

- Add JSON parsing helper for PROXYSQL INTERNAL SESSION responses
- Add test_wait_timeout_json_values() function with 8 test cases:
  * Zero value (should clamp to 1 second)
  * Valid values (1s, 10s, 5min, 1hr, 24hr, 20 days)
  * Value exceeding 20 days (should clamp to maximum)
- Validate that wait_timeout appears in session JSON output
- Test plan increased from 4 to 12 tests total
- Provides comprehensive validation of wait_timeout clamping behavior

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

@@ -4,6 +4,7 @@
  */
 
 #include <unistd.h>
+#include <json/json.h>
 
 #include "mysql.h"
 
@@ -31,6 +32,40 @@ int run_q(MYSQL *mysql, const char *q) {
 	return 0;
 }
 
+// Helper function to parse JSON value from PROXYSQL INTERNAL SESSION result
+int extract_wait_timeout_from_json(MYSQL* mysql, unsigned long long &wait_timeout_value) {
+	MYSQL_RES* res = mysql_store_result(mysql);
+	if (!res) return 0;
+
+	MYSQL_ROW row = mysql_fetch_row(res);
+	if (!row) {
+		mysql_free_result(res);
+		return 0;
+	}
+
+	Json::Value root;
+	Json::CharReaderBuilder builder;
+	Json::CharReader* reader = builder.newCharReader();
+
+	std::string errors;
+	bool parsingSuccessful = reader->parse(row[0], row[0] + strlen(row[0]), &root, &errors);
+	delete reader;
+
+	mysql_free_result(res);
+
+	if (!parsingSuccessful) {
+		diag("JSON parsing failed: %s", errors.c_str());
+		return 0;
+	}
+
+	if (root.isMember("wait_timeout") && root["wait_timeout"].isUInt64()) {
+		wait_timeout_value = root["wait_timeout"].asUInt64();
+		return 1;
+	}
+
+	return 0;
+}
+
 int test_session_timeout(CommandLine *cl, MYSQL *admin) {
 	diag("Test: %s", __func__);
 
@@ -84,8 +119,72 @@ int test_session_timeout_exceed_global_timeout(CommandLine *cl, MYSQL *admin) {
 	return EXIT_SUCCESS;
 }
 
+int test_wait_timeout_json_values(CommandLine *cl, MYSQL *admin) {
+	diag("Test: %s - Testing various wait_timeout values and JSON validation", __func__);
+
+	MYSQL_QUERY_T(admin, "SET mysql-wait_timeout=60000"); // 60 seconds global timeout
+	MYSQL_QUERY_T(admin, "LOAD MYSQL VARIABLES 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_FAILURE;
+	}
+
+	struct TestCase {
+		const char* set_query;
+		unsigned long long expected_ms;
+		const char* description;
+	};
+
+	TestCase test_cases[] = {
+		{"SET wait_timeout=0", 1000, "Zero value should be clamped to 1 second"},
+		{"SET wait_timeout=1", 1000, "1 second should be accepted"},
+		{"SET wait_timeout=10", 10000, "10 seconds should be accepted"},
+		{"SET wait_timeout=300", 300000, "5 minutes should be accepted"},
+		{"SET wait_timeout=3600", 3600000, "1 hour should be accepted"},
+		{"SET wait_timeout=86400", 86400000, "24 hours should be accepted"},
+		{"SET wait_timeout=1728000", 1728000000, "20 days should be accepted"},
+		{"SET wait_timeout=1728001", 1728000000, "Value exceeding 20 days should be clamped"}
+	};
+
+	int test_count = sizeof(test_cases) / sizeof(test_cases[0]);
+
+	for (int i = 0; i < test_count; i++) {
+		diag("Testing: %s", test_cases[i].description);
+
+		// Set the wait_timeout value
+		MYSQL_QUERY_T(proxy, test_cases[i].set_query);
+
+		// Query PROXYSQL INTERNAL SESSION to get JSON
+		if (mysql_query(proxy, "PROXYSQL INTERNAL SESSION")) {
+			fprintf(stderr, "File %s, line %d, Error: %s\n", __FILE__, __LINE__, mysql_error(proxy));
+			mysql_close(proxy);
+			return EXIT_FAILURE;
+		}
+
+		unsigned long long actual_wait_timeout;
+		int json_result = extract_wait_timeout_from_json(proxy, actual_wait_timeout);
+
+		if (json_result) {
+			ok(actual_wait_timeout == test_cases[i].expected_ms,
+			   "wait_timeout JSON value matches expected: %llu ms == %llu ms",
+			   actual_wait_timeout, test_cases[i].expected_ms);
+			diag("Expected: %llu ms, Got: %llu ms", test_cases[i].expected_ms, actual_wait_timeout);
+		} else {
+			fail("Failed to extract wait_timeout from JSON");
+		}
+
+		// Small delay between tests
+		usleep(10000);
+	}
+
+	mysql_close(proxy);
+	return EXIT_SUCCESS;
+}
+
 int main(int argc, char** argv) {
-	plan(4);
+	plan(12); // 4 + 8 tests for new JSON validation function
 
 	CommandLine cl;
 	if (cl.getEnv()) {
@@ -109,6 +208,11 @@ int main(int argc, char** argv) {
 		return exit_status();
 	}
 
+	rc = test_wait_timeout_json_values(&cl, admin);
+	if (rc != EXIT_SUCCESS) {
+		return exit_status();
+	}
+
 	mysql_close(admin);
 	return exit_status();
 }