inventory-barcode-system/__tests__/InventoryModel.test.js

const Inventory = require('../models/Inventory');

describe('Inventory Model - Basic Tests', () => {
    test('should create inventory instance', () => {
        const inventory = new Inventory({
            product_id: 1,
            current_level: 50,
            minimum_level: 10,
            updated_by: 'testuser'
        });

        expect(inventory.product_id).toBe(1);
        expect(inventory.current_level).toBe(50);
        expect(inventory.minimum_level).toBe(10);
        expect(inventory.updated_by).toBe('testuser');
    });

    test('should validate required product_id', () => {
        const inventory = new Inventory({
            current_level: 50,
            minimum_level: 10
        });
        const validation = inventory.validate();

        expect(validation.isValid).toBe(false);
        expect(validation.errors).toContain('Product ID is required and must be a number');
    });

    test('should validate current_level is non-negative', () => {
        const inventory = new Inventory({
            product_id: 1,
            current_level: -5,
            minimum_level: 10
        });
        const validation = inventory.validate();

        expect(validation.isValid).toBe(false);
        expect(validation.errors).toContain('Current level must be a non-negative number');
    });

    test('should pass validation with valid data', () => {
        const inventory = new Inventory({
            product_id: 1,
            current_level: 50,
            minimum_level: 10,
            maximum_level: 100,
            updated_by: 'testuser'
        });
        const validation = inventory.validate();

        expect(validation.isValid).toBe(true);
        expect(validation.errors).toHaveLength(0);
    });

    test('should convert to JSON', () => {
        const inventoryData = {
            id: 1,
            product_id: 1,
            current_level: 50,
            minimum_level: 10,
            maximum_level: 100,
            last_updated: '2023-01-01 00:00:00',
            updated_by: 'testuser',
            version: 1
        };

        const inventory = new Inventory(inventoryData);
        const json = inventory.toJSON();

        expect(json).toEqual(inventoryData);
    });
});

describe('Inventory Model - Database Tests', () => {
    const database = require('../models/database');
    let testProduct;

    beforeAll(async () => {
        // Initialize database for testing
        database.initialize();
    });

    afterAll(() => {
        // Close database connection
        database.close();
    });

    beforeEach(() => {
        // Clear tables before each test
        const db = database.getDatabase();
        db.exec('DELETE FROM inventory_history');
        db.exec('DELETE FROM inventory');
        db.exec('DELETE FROM products');

        // Create a test product
        const insertStmt = db.prepare(`
      INSERT INTO products (product_code, description, category, unit_of_measure)
      VALUES (?, ?, ?, ?)
    `);
        const result = insertStmt.run('TEST001', 'Test Product', 'Electronics', 'pieces');
        testProduct = { id: result.lastInsertRowid, product_code: 'TEST001' };
    });

    test('should create inventory record for a product', async () => {
        const inventory = await Inventory.createForProduct(
            testProduct.id,
            100,
            10,
            200,
            'testuser'
        );

        expect(inventory.product_id).toBe(testProduct.id);
        expect(inventory.current_level).toBe(100);
        expect(inventory.minimum_level).toBe(10);
        expect(inventory.maximum_level).toBe(200);
        expect(inventory.updated_by).toBe('testuser');
        expect(inventory.id).toBeDefined();
    });

    test('should update inventory level and create audit record', async () => {
        // Create initial inventory
        await Inventory.createForProduct(testProduct.id, 100, 10, 200, 'system');

        const updatedInventory = await Inventory.updateInventoryLevel(
            testProduct.id,
            150,
            'Restocking from supplier',
            'testuser'
        );

        expect(updatedInventory.product_id).toBe(testProduct.id);
        expect(updatedInventory.current_level).toBe(150);
        expect(updatedInventory.updated_by).toBe('testuser');
        expect(updatedInventory.version).toBe(2); // Version should increment

        // Verify audit trail was created
        const history = await Inventory.getInventoryHistory(testProduct.id);
        expect(history).toHaveLength(2); // Initial creation + update
        expect(history[0].old_level).toBe(100);
        expect(history[0].new_level).toBe(150);
        expect(history[0].change_reason).toBe('Restocking from supplier');
        expect(history[0].updated_by).toBe('testuser');
    });

    test('should handle concurrent updates with optimistic locking', async () => {
        // Create initial inventory
        await Inventory.createForProduct(testProduct.id, 100, 10, 200, 'system');

        // Simulate concurrent access by getting the same record twice
        const inventory1 = await Inventory.getByProductId(testProduct.id);
        const inventory2 = await Inventory.getByProductId(testProduct.id);

        // First update should succeed
        inventory1.current_level = 120;
        inventory1.updated_by = 'user1';
        await inventory1.save();

        // Second update should fail due to version mismatch
        inventory2.current_level = 110;
        inventory2.updated_by = 'user2';

        await expect(inventory2.save()).rejects.toThrow('Concurrent update detected');
    });
});