feat(testing): add full integration test suite

This commit introduces a comprehensive integration test suite for the pgsql-broker.

The test suite includes:
- A Docker/Podman environment for running a PostgreSQL database, managed via a .
- Integration tests that cover the broker's lifecycle, including job creation, execution, and instance management.
- A GitHub Actions workflow to automate the execution of all tests on push and pull requests.
- A dedicated test configuration file () and helper test files.

refactor(worker): fix job processing transaction
- The worker's job processing now uses a single transaction to fetch and run a job, resolving a race condition where jobs were not in the 'running' state when being executed.
- The broker's database instance registration is now more robust, handling cases where another instance is already active.

The Makefile has been significantly updated to orchestrate the entire test flow, including setting up the database, starting/stopping the broker, and running unit and integration tests separately.

pkg/broker/database_instance.go

@@ -2,6 +2,7 @@ package broker
 
 import (
 	"context"
+	"database/sql" // Import sql package
 	"encoding/json"
 	"fmt"
 	"os"
@@ -133,22 +134,68 @@ func (i *DatabaseInstance) Stop() error {
 func (i *DatabaseInstance) registerInstance() error {
 	var retval int
 	var errmsg string
-	var instanceID int64
+	var nullableInstanceID sql.NullInt64 // Change to nullable type
 
+	i.logger.Debug("registering instance", "name", i.Name, "hostname", i.Hostname, "pid", i.PID, "version", i.Version, "queue_count", i.dbConfig.QueueCount)
 	err := i.db.QueryRow(i.ctx,
 		"SELECT p_retval, p_errmsg, p_instance_id FROM broker_register_instance($1, $2, $3, $4, $5)",
 		i.Name, i.Hostname, i.PID, i.Version, i.dbConfig.QueueCount,
-	).Scan(&retval, &errmsg, &instanceID)
+	).Scan(&retval, &errmsg, &nullableInstanceID)
 
 	if err != nil {
+		i.logger.Error("query error during instance registration", "error", err)
 		return fmt.Errorf("query error: %w", err)
 	}
 
-	if retval > 0 {
+	if retval == 3 {
+		i.logger.Warn("another broker instance is already active, attempting to retrieve ID", "error", errmsg)
+		// Try to retrieve the ID of the active instance
+		var activeID int64
+		err := i.db.QueryRow(i.ctx,
+			"SELECT id_broker_queueinstance FROM broker_queueinstance WHERE name = $1 AND hostname = $2 AND status = 'active' ORDER BY started_at DESC LIMIT 1",
+			i.Name, i.Hostname,
+		).Scan(&activeID)
+		if err != nil {
+			i.logger.Error("failed to retrieve ID of active instance", "error", err)
+			return fmt.Errorf("failed to retrieve ID of active instance: %w", err)
+		}
+		i.ID = activeID
+		i.logger.Info("retrieved active instance ID", "id", i.ID)
+		return nil
+	} else if retval > 0 {
+		i.logger.Error("broker_register_instance error", "retval", retval, "errmsg", errmsg)
 		return fmt.Errorf("broker_register_instance error: %s", errmsg)
 	}
 
-	i.ID = instanceID
+	// If successfully registered, nullableInstanceID.Valid will be true
+	if nullableInstanceID.Valid {
+		i.ID = nullableInstanceID.Int64
+		i.logger.Info("registered new instance", "id", i.ID)
+
+	// Debug logging: Retrieve all entries from broker_queueinstance
+	rows, err := i.db.Query(i.ctx, "SELECT id_broker_queueinstance, name, hostname, status FROM broker_queueinstance")
+	if err != nil {
+		i.logger.Error("debug query failed", "error", err)
+	} else {
+		defer rows.Close()
+		for rows.Next() {
+			var id int64
+			var name, hostname, status string
+			if err := rows.Scan(&id, &name, &hostname, &status); err != nil {
+				i.logger.Error("debug scan failed", "error", err)
+				break
+			}
+			i.logger.Debug("broker_queueinstance entry", "id", id, "name", name, "hostname", hostname, "status", status)
+		}
+	}
+	} else {
+		// This case should ideally not happen if retval is 0 (success)
+		// but if it does, it means p_instance_id was NULL despite success.
+		// This would be an unexpected scenario.
+		i.logger.Error("broker_register_instance returned success but no instance ID", "retval", retval, "errmsg", errmsg)
+		return fmt.Errorf("broker_register_instance returned success but no instance ID")
+	}
+
 	return nil
 }
 
@@ -323,4 +370,4 @@ func (i *DatabaseInstance) GetStats() map[string]interface{} {
 	stats["queues"] = queueStats
 
 	return stats
-}
+}