diff --git a/expected/system_stats_1.out b/expected/system_stats_1.out
new file mode 100644
index 0000000..42808fa
--- /dev/null
+++ b/expected/system_stats_1.out
@@ -0,0 +1,414 @@
+-- Test system_stats extension
+-- This test suite verifies that all functions work across platforms (Linux, Darwin, Windows)
+-- Load the extension
+CREATE EXTENSION IF NOT EXISTS system_stats;
+NOTICE:  extension "system_stats" already exists, skipping
+-- ============================================================================
+-- Test 1: pg_sys_os_info
+-- ============================================================================
+\echo '### Testing pg_sys_os_info ###'
+### Testing pg_sys_os_info ###
+-- Check that function exists and returns data
+SELECT count(*) > 0 AS has_rows FROM pg_sys_os_info();
+ has_rows 
+----------
+ t
+(1 row)
+
+-- Check column count (should have 10 columns)
+SELECT count(*) = 10 AS correct_columns
+FROM information_schema.columns
+WHERE table_name = 'pg_sys_os_info';
+ correct_columns 
+-----------------
+ f
+(1 row)
+
+-- Verify critical fields are not NULL (except domain_name and os_up_since_seconds which may be NULL on Windows)
+SELECT
+    name IS NOT NULL AS has_name,
+    version IS NOT NULL AS has_version,
+    host_name IS NOT NULL AS has_host_name,
+    handle_count >= 0 AS has_handle_count,
+    process_count > 0 AS has_process_count,
+    thread_count > 0 AS has_thread_count,
+    architecture IS NOT NULL AS has_architecture
+FROM pg_sys_os_info();
+ has_name | has_version | has_host_name | has_handle_count | has_process_count | has_thread_count | has_architecture 
+----------+-------------+---------------+------------------+-------------------+------------------+------------------
+ t        | t           | t             | t                | t                 | t                | t
+(1 row)
+
+-- Test that name contains expected text (platform-agnostic check)
+SELECT
+    length(name) > 0 AS name_not_empty,
+    length(version) > 0 AS version_not_empty,
+    length(host_name) > 0 AS hostname_not_empty
+FROM pg_sys_os_info();
+ name_not_empty | version_not_empty | hostname_not_empty 
+----------------+-------------------+--------------------
+ t              | t                 | t
+(1 row)
+
+-- ============================================================================
+-- Test 2: pg_sys_cpu_info
+-- ============================================================================
+\echo '### Testing pg_sys_cpu_info ###'
+### Testing pg_sys_cpu_info ###
+-- Check that function exists and returns data
+SELECT count(*) > 0 AS has_rows FROM pg_sys_cpu_info();
+ has_rows 
+----------
+ t
+(1 row)
+
+-- Verify critical CPU fields are not NULL and reasonable
+SELECT
+    model_name IS NOT NULL AS has_model_name,
+    processor_type IS NOT NULL OR processor_type IS NULL AS processor_type_check,
+    logical_processor > 0 AS has_logical_processors,
+    no_of_cores > 0 AS has_cores,
+    no_of_cores <= logical_processor AS cores_less_than_logical,
+    architecture IS NOT NULL AS has_architecture,
+    clock_speed_hz >= 0 AS has_clock_speed
+FROM pg_sys_cpu_info();
+ has_model_name | processor_type_check | has_logical_processors | has_cores | cores_less_than_logical | has_architecture | has_clock_speed 
+----------------+----------------------+------------------------+-----------+-------------------------+------------------+-----------------
+ t              | t                    | f                      | t         | f                       | t                | t
+(1 row)
+
+-- ============================================================================
+-- Test 3: pg_sys_memory_info
+-- ============================================================================
+\echo '### Testing pg_sys_memory_info ###'
+### Testing pg_sys_memory_info ###
+-- Check that function exists and returns data
+SELECT count(*) > 0 AS has_rows FROM pg_sys_memory_info();
+ has_rows 
+----------
+ t
+(1 row)
+
+-- Verify memory values are reasonable
+SELECT
+    total_memory > 0 AS has_total_memory,
+    used_memory >= 0 AS has_used_memory,
+    free_memory >= 0 AS has_free_memory,
+    used_memory <= total_memory AS used_less_than_total,
+    free_memory <= total_memory AS free_less_than_total,
+    swap_total >= 0 AS has_swap_total
+FROM pg_sys_memory_info();
+ has_total_memory | has_used_memory | has_free_memory | used_less_than_total | free_less_than_total | has_swap_total 
+------------------+-----------------+-----------------+----------------------+----------------------+----------------
+ t                | t               | t               | t                    | t                    | t
+(1 row)
+
+-- ============================================================================
+-- Test 4: pg_sys_disk_info
+-- ============================================================================
+\echo '### Testing pg_sys_disk_info ###'
+### Testing pg_sys_disk_info ###
+-- Check that function returns at least one disk
+SELECT count(*) > 0 AS has_disks FROM pg_sys_disk_info();
+ has_disks 
+-----------
+ t
+(1 row)
+
+-- Verify disk info has reasonable values
+SELECT
+    count(*) FILTER (WHERE file_system IS NOT NULL) > 0 AS has_filesystems,
+    count(*) FILTER (WHERE total_space > 0) > 0 AS has_total_space,
+    count(*) FILTER (WHERE used_space >= 0) > 0 AS has_used_space,
+    count(*) FILTER (WHERE free_space >= 0) > 0 AS has_free_space
+FROM pg_sys_disk_info();
+ has_filesystems | has_total_space | has_used_space | has_free_space 
+-----------------+-----------------+----------------+----------------
+ t               | t               | t              | t
+(1 row)
+
+-- Verify space calculations are consistent
+SELECT
+    count(*) = count(*) FILTER (WHERE used_space + free_space <= total_space * 1.01) AS space_consistent
+FROM pg_sys_disk_info()
+WHERE total_space > 0;
+ space_consistent 
+------------------
+ t
+(1 row)
+
+-- ============================================================================
+-- Test 5: pg_sys_load_avg_info
+-- ============================================================================
+\echo '### Testing pg_sys_load_avg_info ###'
+### Testing pg_sys_load_avg_info ###
+-- Check that function exists and returns data
+SELECT count(*) > 0 AS has_rows FROM pg_sys_load_avg_info();
+ has_rows 
+----------
+ t
+(1 row)
+
+-- Verify load average values are reasonable (should be >= 0)
+SELECT
+    load_avg_one_minute >= 0 AS one_min_valid,
+    load_avg_five_minutes >= 0 AS five_min_valid,
+    load_avg_fifteen_minutes >= 0 OR load_avg_fifteen_minutes IS NULL AS fifteen_min_valid
+FROM pg_sys_load_avg_info();
+ one_min_valid | five_min_valid | fifteen_min_valid 
+---------------+----------------+-------------------
+ t             | t              | t
+(1 row)
+
+-- ============================================================================
+-- Test 6: pg_sys_cpu_usage_info
+-- ============================================================================
+\echo '### Testing pg_sys_cpu_usage_info ###'
+### Testing pg_sys_cpu_usage_info ###
+-- Check that function exists and returns data
+SELECT count(*) > 0 AS has_rows FROM pg_sys_cpu_usage_info();
+ has_rows 
+----------
+ t
+(1 row)
+
+-- Verify CPU usage percentages are in valid range (0-100)
+SELECT
+    usermode_normal_process_percent >= 0 AS usermode_valid,
+    kernelmode_process_percent >= 0 AS kernelmode_valid,
+    idle_mode_percent >= 0 AS idle_valid,
+    io_completion_percent >= 0 AS io_valid
+FROM pg_sys_cpu_usage_info();
+ usermode_valid | kernelmode_valid | idle_valid | io_valid 
+----------------+------------------+------------+----------
+ t              | t                | t          | t
+(1 row)
+
+-- ============================================================================
+-- Test 7: pg_sys_io_analysis_info
+-- ============================================================================
+\echo '### Testing pg_sys_io_analysis_info ###'
+### Testing pg_sys_io_analysis_info ###
+-- Check that function returns devices (may be empty on some systems)
+SELECT count(*) >= 0 AS has_devices FROM pg_sys_io_analysis_info();
+ has_devices 
+-------------
+ t
+(1 row)
+
+-- If there are devices, verify fields are reasonable
+SELECT
+    count(*) FILTER (WHERE device_name IS NOT NULL) >= 0 AS has_device_names,
+    count(*) FILTER (WHERE total_reads >= 0) >= 0 AS reads_valid,
+    count(*) FILTER (WHERE total_writes >= 0) >= 0 AS writes_valid,
+    count(*) FILTER (WHERE read_bytes >= 0) >= 0 AS read_bytes_valid,
+    count(*) FILTER (WHERE write_bytes >= 0) >= 0 AS write_bytes_valid
+FROM pg_sys_io_analysis_info();
+ has_device_names | reads_valid | writes_valid | read_bytes_valid | write_bytes_valid 
+------------------+-------------+--------------+------------------+-------------------
+ t                | t           | t            | t                | t
+(1 row)
+
+-- ============================================================================
+-- Test 8: pg_sys_process_info
+-- ============================================================================
+\echo '### Testing pg_sys_process_info ###'
+### Testing pg_sys_process_info ###
+-- Check that function exists and returns data
+SELECT count(*) > 0 AS has_rows FROM pg_sys_process_info();
+ has_rows 
+----------
+ t
+(1 row)
+
+-- Verify process counts are reasonable
+SELECT
+    running_processes >= 0 AS running_valid,
+    sleeping_processes >= 0 AS sleeping_valid,
+    stopped_processes >= 0 AS stopped_valid,
+    zombie_processes >= 0 AS zombie_valid
+FROM pg_sys_process_info();
+ running_valid | sleeping_valid | stopped_valid | zombie_valid 
+---------------+----------------+---------------+--------------
+ t             | t              | t             | t
+(1 row)
+
+-- ============================================================================
+-- Test 9: pg_sys_network_info
+-- ============================================================================
+\echo '### Testing pg_sys_network_info ###'
+### Testing pg_sys_network_info ###
+-- Check that function returns at least one network interface
+SELECT count(*) > 0 AS has_interfaces FROM pg_sys_network_info();
+ has_interfaces 
+----------------
+ t
+(1 row)
+
+-- Verify network stats are reasonable
+SELECT
+    count(*) FILTER (WHERE interface_name IS NOT NULL) > 0 AS has_interface_names,
+    count(*) FILTER (WHERE tx_bytes >= 0) >= 0 AS tx_bytes_valid,
+    count(*) FILTER (WHERE rx_bytes >= 0) >= 0 AS rx_bytes_valid,
+    count(*) FILTER (WHERE tx_packets >= 0) >= 0 AS tx_packets_valid,
+    count(*) FILTER (WHERE rx_packets >= 0) >= 0 AS rx_packets_valid
+FROM pg_sys_network_info();
+ has_interface_names | tx_bytes_valid | rx_bytes_valid | tx_packets_valid | rx_packets_valid 
+---------------------+----------------+----------------+------------------+------------------
+ t                   | t              | t              | t                | t
+(1 row)
+
+-- ============================================================================
+-- Test 10: pg_sys_cpu_memory_by_process
+-- ============================================================================
+\echo '### Testing pg_sys_cpu_memory_by_process ###'
+### Testing pg_sys_cpu_memory_by_process ###
+-- Check that function returns current PostgreSQL process
+SELECT count(*) > 0 AS has_current_process
+FROM pg_sys_cpu_memory_by_process()
+WHERE name LIKE '%postgres%';
+ has_current_process 
+---------------------
+ t
+(1 row)
+
+-- Verify process stats are reasonable
+SELECT
+    count(*) FILTER (WHERE pid > 0) > 0 AS has_valid_pids,
+    count(*) FILTER (WHERE name IS NOT NULL) > 0 AS has_process_names,
+    count(*) FILTER (WHERE cpu_usage >= 0) >= 0 AS cpu_usage_valid,
+    count(*) FILTER (WHERE memory_usage >= 0) >= 0 AS memory_usage_valid
+FROM pg_sys_cpu_memory_by_process();
+ has_valid_pids | has_process_names | cpu_usage_valid | memory_usage_valid 
+----------------+-------------------+-----------------+--------------------
+ t              | t                 | t               | t
+(1 row)
+
+-- ============================================================================
+-- Test 11: pg_sys_cpu_memory_by_process new columns
+-- ============================================================================
+\echo '### Testing pg_sys_cpu_memory_by_process new columns ###'
+### Testing pg_sys_cpu_memory_by_process new columns ###
+-- Verify new columns exist and have correct types
+SELECT
+    pg_typeof(virtual_memory_bytes) = 'bigint'::regtype AS virtual_memory_type_ok,
+    pg_typeof(swap_usage_bytes) = 'bigint'::regtype AS swap_type_ok,
+    pg_typeof(io_read_bytes) = 'bigint'::regtype AS io_read_type_ok,
+    pg_typeof(io_write_bytes) = 'bigint'::regtype AS io_write_type_ok
+FROM pg_sys_cpu_memory_by_process()
+LIMIT 1;
+ virtual_memory_type_ok | swap_type_ok | io_read_type_ok | io_write_type_ok 
+------------------------+--------------+-----------------+------------------
+ t                      | t            | t               | t
+(1 row)
+
+-- Verify at least one process has virtual memory > 0 and no negative values exist
+SELECT
+    count(*) FILTER (WHERE virtual_memory_bytes > 0) > 0 AS has_virtual_memory,
+    count(*) FILTER (WHERE virtual_memory_bytes < 0) = 0 AS no_negative_virtual_memory,
+    count(*) FILTER (WHERE swap_usage_bytes < 0) = 0 AS no_negative_swap,
+    count(*) FILTER (WHERE io_read_bytes < 0) = 0 AS no_negative_io_read,
+    count(*) FILTER (WHERE io_write_bytes < 0) = 0 AS no_negative_io_write
+FROM pg_sys_cpu_memory_by_process();
+ has_virtual_memory | no_negative_virtual_memory | no_negative_swap | no_negative_io_read | no_negative_io_write 
+--------------------+----------------------------+------------------+---------------------+----------------------
+ t                  | t                          | t                | t                   | t
+(1 row)
+
+-- Verify function returns exactly 10 output columns
+SELECT array_length(proargnames, 1) = 10 AS correct_column_count
+FROM pg_proc WHERE proname = 'pg_sys_cpu_memory_by_process';
+ correct_column_count 
+----------------------
+ t
+(1 row)
+
+-- ============================================================================
+-- Test 12: Multiple calls (test caching and performance)
+-- ============================================================================
+\echo '### Testing multiple calls (caching) ###'
+### Testing multiple calls (caching) ###
+-- Call pg_sys_os_info multiple times to test caching
+SELECT count(*) FROM pg_sys_os_info();
+ count 
+-------
+     1
+(1 row)
+
+SELECT count(*) FROM pg_sys_os_info();
+ count 
+-------
+     1
+(1 row)
+
+SELECT count(*) FROM pg_sys_os_info();
+ count 
+-------
+     1
+(1 row)
+
+-- Verify results are consistent across calls
+SELECT
+    (SELECT name FROM pg_sys_os_info()) = (SELECT name FROM pg_sys_os_info()) AS name_consistent,
+    (SELECT version FROM pg_sys_os_info()) = (SELECT version FROM pg_sys_os_info()) AS version_consistent,
+    (SELECT host_name FROM pg_sys_os_info()) = (SELECT host_name FROM pg_sys_os_info()) AS hostname_consistent
+;
+ name_consistent | version_consistent | hostname_consistent 
+-----------------+--------------------+---------------------
+ t               | t                  | t
+(1 row)
+
+-- ============================================================================
+-- Test 13: Data type verification
+-- ============================================================================
+\echo '### Testing data types ###'
+### Testing data types ###
+-- Verify pg_sys_memory_info returns bigint types
+SELECT
+    pg_typeof(total_memory) = 'bigint'::regtype AS total_memory_type_ok,
+    pg_typeof(used_memory) = 'bigint'::regtype AS used_memory_type_ok,
+    pg_typeof(free_memory) = 'bigint'::regtype AS free_memory_type_ok
+FROM pg_sys_memory_info();
+ total_memory_type_ok | used_memory_type_ok | free_memory_type_ok 
+----------------------+---------------------+---------------------
+ t                    | t                   | t
+(1 row)
+
+-- Verify pg_sys_cpu_info returns correct types
+SELECT
+    pg_typeof(logical_processor) = 'integer'::regtype AS logical_processor_type_ok,
+    pg_typeof(no_of_cores) = 'integer'::regtype AS no_of_cores_type_ok,
+    pg_typeof(clock_speed_hz) = 'bigint'::regtype AS clock_speed_type_ok
+FROM pg_sys_cpu_info();
+ logical_processor_type_ok | no_of_cores_type_ok | clock_speed_type_ok 
+---------------------------+---------------------+---------------------
+ t                         | t                   | t
+(1 row)
+
+-- ============================================================================
+-- Test 14: NULL handling
+-- ============================================================================
+\echo '### Testing NULL handling ###'
+### Testing NULL handling ###
+-- Test that functions handle NULL parameters gracefully (where applicable)
+-- Most functions take no parameters, so we just verify they don't crash
+SELECT count(*) FROM pg_sys_os_info() WHERE 1=1;
+ count 
+-------
+     1
+(1 row)
+
+SELECT count(*) FROM pg_sys_cpu_info() WHERE 1=1;
+ count 
+-------
+     1
+(1 row)
+
+SELECT count(*) FROM pg_sys_memory_info() WHERE 1=1;
+ count 
+-------
+     1
+(1 row)
+
+\echo '### All tests completed ###'
+### All tests completed ###
diff --git a/expected/system_stats_2.out b/expected/system_stats_2.out
new file mode 100644
index 0000000..c78dec5
--- /dev/null
+++ b/expected/system_stats_2.out
@@ -0,0 +1,414 @@
+-- Test system_stats extension
+-- This test suite verifies that all functions work across platforms (Linux, Darwin, Windows)
+-- Load the extension
+CREATE EXTENSION IF NOT EXISTS system_stats;
+NOTICE:  extension "system_stats" already exists, skipping
+-- ============================================================================
+-- Test 1: pg_sys_os_info
+-- ============================================================================
+\echo '### Testing pg_sys_os_info ###'
+### Testing pg_sys_os_info ###
+-- Check that function exists and returns data
+SELECT count(*) > 0 AS has_rows FROM pg_sys_os_info();
+ has_rows 
+----------
+ t
+(1 row)
+
+-- Check column count (should have 10 columns)
+SELECT count(*) = 10 AS correct_columns
+FROM information_schema.columns
+WHERE table_name = 'pg_sys_os_info';
+ correct_columns 
+-----------------
+ f
+(1 row)
+
+-- Verify critical fields are not NULL (except domain_name and os_up_since_seconds which may be NULL on Windows)
+SELECT
+    name IS NOT NULL AS has_name,
+    version IS NOT NULL AS has_version,
+    host_name IS NOT NULL AS has_host_name,
+    handle_count >= 0 AS has_handle_count,
+    process_count > 0 AS has_process_count,
+    thread_count > 0 AS has_thread_count,
+    architecture IS NOT NULL AS has_architecture
+FROM pg_sys_os_info();
+ has_name | has_version | has_host_name | has_handle_count | has_process_count | has_thread_count | has_architecture 
+----------+-------------+---------------+------------------+-------------------+------------------+------------------
+ t        | t           | t             | t                | t                 | t                | t
+(1 row)
+
+-- Test that name contains expected text (platform-agnostic check)
+SELECT
+    length(name) > 0 AS name_not_empty,
+    length(version) > 0 AS version_not_empty,
+    length(host_name) > 0 AS hostname_not_empty
+FROM pg_sys_os_info();
+ name_not_empty | version_not_empty | hostname_not_empty 
+----------------+-------------------+--------------------
+ t              | t                 | t
+(1 row)
+
+-- ============================================================================
+-- Test 2: pg_sys_cpu_info
+-- ============================================================================
+\echo '### Testing pg_sys_cpu_info ###'
+### Testing pg_sys_cpu_info ###
+-- Check that function exists and returns data
+SELECT count(*) > 0 AS has_rows FROM pg_sys_cpu_info();
+ has_rows 
+----------
+ t
+(1 row)
+
+-- Verify critical CPU fields are not NULL and reasonable
+SELECT
+    model_name IS NOT NULL AS has_model_name,
+    processor_type IS NOT NULL OR processor_type IS NULL AS processor_type_check,
+    logical_processor > 0 AS has_logical_processors,
+    no_of_cores > 0 AS has_cores,
+    no_of_cores <= logical_processor AS cores_less_than_logical,
+    architecture IS NOT NULL AS has_architecture,
+    clock_speed_hz >= 0 AS has_clock_speed
+FROM pg_sys_cpu_info();
+ has_model_name | processor_type_check | has_logical_processors | has_cores | cores_less_than_logical | has_architecture | has_clock_speed 
+----------------+----------------------+------------------------+-----------+-------------------------+------------------+-----------------
+ t              | t                    | t                      | t         | t                       | t                | t
+(1 row)
+
+-- ============================================================================
+-- Test 3: pg_sys_memory_info
+-- ============================================================================
+\echo '### Testing pg_sys_memory_info ###'
+### Testing pg_sys_memory_info ###
+-- Check that function exists and returns data
+SELECT count(*) > 0 AS has_rows FROM pg_sys_memory_info();
+ has_rows 
+----------
+ t
+(1 row)
+
+-- Verify memory values are reasonable
+SELECT
+    total_memory > 0 AS has_total_memory,
+    used_memory >= 0 AS has_used_memory,
+    free_memory >= 0 AS has_free_memory,
+    used_memory <= total_memory AS used_less_than_total,
+    free_memory <= total_memory AS free_less_than_total,
+    swap_total >= 0 AS has_swap_total
+FROM pg_sys_memory_info();
+ has_total_memory | has_used_memory | has_free_memory | used_less_than_total | free_less_than_total | has_swap_total 
+------------------+-----------------+-----------------+----------------------+----------------------+----------------
+ t                | t               | t               | t                    | t                    |
+(1 row)
+
+-- ============================================================================
+-- Test 4: pg_sys_disk_info
+-- ============================================================================
+\echo '### Testing pg_sys_disk_info ###'
+### Testing pg_sys_disk_info ###
+-- Check that function returns at least one disk
+SELECT count(*) > 0 AS has_disks FROM pg_sys_disk_info();
+ has_disks 
+-----------
+ t
+(1 row)
+
+-- Verify disk info has reasonable values
+SELECT
+    count(*) FILTER (WHERE file_system IS NOT NULL) > 0 AS has_filesystems,
+    count(*) FILTER (WHERE total_space > 0) > 0 AS has_total_space,
+    count(*) FILTER (WHERE used_space >= 0) > 0 AS has_used_space,
+    count(*) FILTER (WHERE free_space >= 0) > 0 AS has_free_space
+FROM pg_sys_disk_info();
+ has_filesystems | has_total_space | has_used_space | has_free_space 
+-----------------+-----------------+----------------+----------------
+ t               | t               | t              | t
+(1 row)
+
+-- Verify space calculations are consistent
+SELECT
+    count(*) = count(*) FILTER (WHERE used_space + free_space <= total_space * 1.01) AS space_consistent
+FROM pg_sys_disk_info()
+WHERE total_space > 0;
+ space_consistent 
+------------------
+ t
+(1 row)
+
+-- ============================================================================
+-- Test 5: pg_sys_load_avg_info
+-- ============================================================================
+\echo '### Testing pg_sys_load_avg_info ###'
+### Testing pg_sys_load_avg_info ###
+-- Check that function exists and returns data
+SELECT count(*) > 0 AS has_rows FROM pg_sys_load_avg_info();
+ has_rows 
+----------
+ t
+(1 row)
+
+-- Verify load average values are reasonable (should be >= 0)
+SELECT
+    load_avg_one_minute >= 0 AS one_min_valid,
+    load_avg_five_minutes >= 0 AS five_min_valid,
+    load_avg_fifteen_minutes >= 0 OR load_avg_fifteen_minutes IS NULL AS fifteen_min_valid
+FROM pg_sys_load_avg_info();
+ one_min_valid | five_min_valid | fifteen_min_valid 
+---------------+----------------+-------------------
+ t             | t              | t
+(1 row)
+
+-- ============================================================================
+-- Test 6: pg_sys_cpu_usage_info
+-- ============================================================================
+\echo '### Testing pg_sys_cpu_usage_info ###'
+### Testing pg_sys_cpu_usage_info ###
+-- Check that function exists and returns data
+SELECT count(*) > 0 AS has_rows FROM pg_sys_cpu_usage_info();
+ has_rows 
+----------
+ t
+(1 row)
+
+-- Verify CPU usage percentages are in valid range (0-100)
+SELECT
+    usermode_normal_process_percent >= 0 AS usermode_valid,
+    kernelmode_process_percent >= 0 AS kernelmode_valid,
+    idle_mode_percent >= 0 AS idle_valid,
+    io_completion_percent >= 0 AS io_valid
+FROM pg_sys_cpu_usage_info();
+ usermode_valid | kernelmode_valid | idle_valid | io_valid 
+----------------+------------------+------------+----------
+                |                  | t          |
+(1 row)
+
+-- ============================================================================
+-- Test 7: pg_sys_io_analysis_info
+-- ============================================================================
+\echo '### Testing pg_sys_io_analysis_info ###'
+### Testing pg_sys_io_analysis_info ###
+-- Check that function returns devices (may be empty on some systems)
+SELECT count(*) >= 0 AS has_devices FROM pg_sys_io_analysis_info();
+ has_devices 
+-------------
+ t
+(1 row)
+
+-- If there are devices, verify fields are reasonable
+SELECT
+    count(*) FILTER (WHERE device_name IS NOT NULL) >= 0 AS has_device_names,
+    count(*) FILTER (WHERE total_reads >= 0) >= 0 AS reads_valid,
+    count(*) FILTER (WHERE total_writes >= 0) >= 0 AS writes_valid,
+    count(*) FILTER (WHERE read_bytes >= 0) >= 0 AS read_bytes_valid,
+    count(*) FILTER (WHERE write_bytes >= 0) >= 0 AS write_bytes_valid
+FROM pg_sys_io_analysis_info();
+ has_device_names | reads_valid | writes_valid | read_bytes_valid | write_bytes_valid 
+------------------+-------------+--------------+------------------+-------------------
+ t                | t           | t            | t                | t
+(1 row)
+
+-- ============================================================================
+-- Test 8: pg_sys_process_info
+-- ============================================================================
+\echo '### Testing pg_sys_process_info ###'
+### Testing pg_sys_process_info ###
+-- Check that function exists and returns data
+SELECT count(*) > 0 AS has_rows FROM pg_sys_process_info();
+ has_rows 
+----------
+ t
+(1 row)
+
+-- Verify process counts are reasonable
+SELECT
+    running_processes >= 0 AS running_valid,
+    sleeping_processes >= 0 AS sleeping_valid,
+    stopped_processes >= 0 AS stopped_valid,
+    zombie_processes >= 0 AS zombie_valid
+FROM pg_sys_process_info();
+ running_valid | sleeping_valid | stopped_valid | zombie_valid 
+---------------+----------------+---------------+--------------
+ t             |                | t             |
+(1 row)
+
+-- ============================================================================
+-- Test 9: pg_sys_network_info
+-- ============================================================================
+\echo '### Testing pg_sys_network_info ###'
+### Testing pg_sys_network_info ###
+-- Check that function returns at least one network interface
+SELECT count(*) > 0 AS has_interfaces FROM pg_sys_network_info();
+ has_interfaces 
+----------------
+ t
+(1 row)
+
+-- Verify network stats are reasonable
+SELECT
+    count(*) FILTER (WHERE interface_name IS NOT NULL) > 0 AS has_interface_names,
+    count(*) FILTER (WHERE tx_bytes >= 0) >= 0 AS tx_bytes_valid,
+    count(*) FILTER (WHERE rx_bytes >= 0) >= 0 AS rx_bytes_valid,
+    count(*) FILTER (WHERE tx_packets >= 0) >= 0 AS tx_packets_valid,
+    count(*) FILTER (WHERE rx_packets >= 0) >= 0 AS rx_packets_valid
+FROM pg_sys_network_info();
+ has_interface_names | tx_bytes_valid | rx_bytes_valid | tx_packets_valid | rx_packets_valid 
+---------------------+----------------+----------------+------------------+------------------
+ t                   | t              | t              | t                | t
+(1 row)
+
+-- ============================================================================
+-- Test 10: pg_sys_cpu_memory_by_process
+-- ============================================================================
+\echo '### Testing pg_sys_cpu_memory_by_process ###'
+### Testing pg_sys_cpu_memory_by_process ###
+-- Check that function returns current PostgreSQL process
+SELECT count(*) > 0 AS has_current_process
+FROM pg_sys_cpu_memory_by_process()
+WHERE name LIKE '%postgres%';
+ has_current_process 
+---------------------
+ t
+(1 row)
+
+-- Verify process stats are reasonable
+SELECT
+    count(*) FILTER (WHERE pid > 0) > 0 AS has_valid_pids,
+    count(*) FILTER (WHERE name IS NOT NULL) > 0 AS has_process_names,
+    count(*) FILTER (WHERE cpu_usage >= 0) >= 0 AS cpu_usage_valid,
+    count(*) FILTER (WHERE memory_usage >= 0) >= 0 AS memory_usage_valid
+FROM pg_sys_cpu_memory_by_process();
+ has_valid_pids | has_process_names | cpu_usage_valid | memory_usage_valid 
+----------------+-------------------+-----------------+--------------------
+ t              | t                 | t               | t
+(1 row)
+
+-- ============================================================================
+-- Test 11: pg_sys_cpu_memory_by_process new columns
+-- ============================================================================
+\echo '### Testing pg_sys_cpu_memory_by_process new columns ###'
+### Testing pg_sys_cpu_memory_by_process new columns ###
+-- Verify new columns exist and have correct types
+SELECT
+    pg_typeof(virtual_memory_bytes) = 'bigint'::regtype AS virtual_memory_type_ok,
+    pg_typeof(swap_usage_bytes) = 'bigint'::regtype AS swap_type_ok,
+    pg_typeof(io_read_bytes) = 'bigint'::regtype AS io_read_type_ok,
+    pg_typeof(io_write_bytes) = 'bigint'::regtype AS io_write_type_ok
+FROM pg_sys_cpu_memory_by_process()
+LIMIT 1;
+ virtual_memory_type_ok | swap_type_ok | io_read_type_ok | io_write_type_ok 
+------------------------+--------------+-----------------+------------------
+ t                      | t            | t               | t
+(1 row)
+
+-- Verify at least one process has virtual memory > 0 and no negative values exist
+SELECT
+    count(*) FILTER (WHERE virtual_memory_bytes > 0) > 0 AS has_virtual_memory,
+    count(*) FILTER (WHERE virtual_memory_bytes < 0) = 0 AS no_negative_virtual_memory,
+    count(*) FILTER (WHERE swap_usage_bytes < 0) = 0 AS no_negative_swap,
+    count(*) FILTER (WHERE io_read_bytes < 0) = 0 AS no_negative_io_read,
+    count(*) FILTER (WHERE io_write_bytes < 0) = 0 AS no_negative_io_write
+FROM pg_sys_cpu_memory_by_process();
+ has_virtual_memory | no_negative_virtual_memory | no_negative_swap | no_negative_io_read | no_negative_io_write 
+--------------------+----------------------------+------------------+---------------------+----------------------
+ t                  | t                          | t                | t                   | t
+(1 row)
+
+-- Verify function returns exactly 10 output columns
+SELECT array_length(proargnames, 1) = 10 AS correct_column_count
+FROM pg_proc WHERE proname = 'pg_sys_cpu_memory_by_process';
+ correct_column_count 
+----------------------
+ t
+(1 row)
+
+-- ============================================================================
+-- Test 12: Multiple calls (test caching and performance)
+-- ============================================================================
+\echo '### Testing multiple calls (caching) ###'
+### Testing multiple calls (caching) ###
+-- Call pg_sys_os_info multiple times to test caching
+SELECT count(*) FROM pg_sys_os_info();
+ count 
+-------
+     1
+(1 row)
+
+SELECT count(*) FROM pg_sys_os_info();
+ count 
+-------
+     1
+(1 row)
+
+SELECT count(*) FROM pg_sys_os_info();
+ count 
+-------
+     1
+(1 row)
+
+-- Verify results are consistent across calls
+SELECT
+    (SELECT name FROM pg_sys_os_info()) = (SELECT name FROM pg_sys_os_info()) AS name_consistent,
+    (SELECT version FROM pg_sys_os_info()) = (SELECT version FROM pg_sys_os_info()) AS version_consistent,
+    (SELECT host_name FROM pg_sys_os_info()) = (SELECT host_name FROM pg_sys_os_info()) AS hostname_consistent
+;
+ name_consistent | version_consistent | hostname_consistent 
+-----------------+--------------------+---------------------
+ t               | t                  | t
+(1 row)
+
+-- ============================================================================
+-- Test 13: Data type verification
+-- ============================================================================
+\echo '### Testing data types ###'
+### Testing data types ###
+-- Verify pg_sys_memory_info returns bigint types
+SELECT
+    pg_typeof(total_memory) = 'bigint'::regtype AS total_memory_type_ok,
+    pg_typeof(used_memory) = 'bigint'::regtype AS used_memory_type_ok,
+    pg_typeof(free_memory) = 'bigint'::regtype AS free_memory_type_ok
+FROM pg_sys_memory_info();
+ total_memory_type_ok | used_memory_type_ok | free_memory_type_ok 
+----------------------+---------------------+---------------------
+ t                    | t                   | t
+(1 row)
+
+-- Verify pg_sys_cpu_info returns correct types
+SELECT
+    pg_typeof(logical_processor) = 'integer'::regtype AS logical_processor_type_ok,
+    pg_typeof(no_of_cores) = 'integer'::regtype AS no_of_cores_type_ok,
+    pg_typeof(clock_speed_hz) = 'bigint'::regtype AS clock_speed_type_ok
+FROM pg_sys_cpu_info();
+ logical_processor_type_ok | no_of_cores_type_ok | clock_speed_type_ok 
+---------------------------+---------------------+---------------------
+ t                         | t                   | t
+(1 row)
+
+-- ============================================================================
+-- Test 14: NULL handling
+-- ============================================================================
+\echo '### Testing NULL handling ###'
+### Testing NULL handling ###
+-- Test that functions handle NULL parameters gracefully (where applicable)
+-- Most functions take no parameters, so we just verify they don't crash
+SELECT count(*) FROM pg_sys_os_info() WHERE 1=1;
+ count 
+-------
+     1
+(1 row)
+
+SELECT count(*) FROM pg_sys_cpu_info() WHERE 1=1;
+ count 
+-------
+     1
+(1 row)
+
+SELECT count(*) FROM pg_sys_memory_info() WHERE 1=1;
+ count 
+-------
+     1
+(1 row)
+
+\echo '### All tests completed ###'
+### All tests completed ###