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Testing Your Functions

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Preview Mode

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Accessing Preview

1. Navigate to Apps → Function Lab
2. Select your function
3. Click “Preview” or “Test”
4. Enter test cart data

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Test Scenarios

• Customer tags
• Cart contents
• Product variants
• Order totals
• Geographic locations

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Common Testing Patterns

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Test Customer Segments

// Test VIP customer
{
  "customer": {
    "tags": ["VIP"]
  }
}

// Test first-time customer
{
  "customer": {
    "tags": [],
    "ordersCount": 0
  }
}

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Test Cart Conditions

// Test minimum order value
{
  "cart": {
    "totalAmount": 150.00
  }
}

// Test quantity thresholds
{
  "cart": {
    "lines": [
      {
        "quantity": 5,
        "merchandise": {...}
      }
    ]
  }
}

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Debugging Strategies

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Enable Console Logging

{
  "facts": {
    "debug_total": "cart.totalAmount"
  },
  "conditions": {
    "$debug_total": { "gte": 100 }
  }
}

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Test Conditions in Isolation

// Test just the customer condition
{
  "conditions": {
    "customer.tags": { "includes": "VIP" }
  }
}

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Verify Selector Output

{
  "facts": {
    "selected_items": "cart.lines[?merchandise.product.handle=='t-shirt'].id"
  }
}

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Validation Checklist

• JSON syntax is valid
• All required fields are present
• Predicates are spelled correctly
• Paths reference valid fields
• GIDs are properly formatted
• Discount values are in correct format
• Messages are customer-friendly
• Tested with multiple cart scenarios
• Verified in Shopify preview mode

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Common Issues

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”No discount applied”

1. Conditions not met
2. Wrong path in condition
3. Case-sensitive string comparison
4. Empty selector result

• Check input data matches condition
• Verify field paths exist
• Test with simplified conditions
• Add facts to inspect intermediate values

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”Wrong discount amount”

1. discount_type mismatch (percentage vs fixed)
2. Value format incorrect
3. appliesToEachItem confusion

• Verify discount_type is correct
• Check value is numeric
• Test with round numbers first

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”Discount on wrong products”

1. Selector returns unexpected results
2. Handle doesn’t match
3. GID format issue

• Test selector in facts
• Verify product handles
• Check variant IDs

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Testing Best Practices

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Start Simple

{
  "rules": [
    {
      "conditions": {
        "customer.tags": { "includes": "TEST" }
      },
      "events": [
        {
          "discount": "product_discount",
          "params": {
            "discount_type": "percentage",
            "value": 10,
            "message": "Test Discount"
          }
        }
      ]
    }
  ]
}

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Add Complexity Gradually

1. Additional conditions
2. Facts
3. Complex selectors
4. Multiple events

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Test Edge Cases

• Empty cart
• Single item
• Large quantity
• Zero-price items
• Customer without account

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Document Test Cases

## Test Cases

1. VIP customer with $100+ cart → 15% discount
2. First-time customer → 10% discount
3. Bulk order (10+ items) → $50 off
4. Geographic restriction (US only) → No discount for CA

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Performance Testing

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Monitor Execution Time

• Keep rules simple when possible
• Limit fact complexity
• Use direct targeting over selectors
• Test with realistic cart sizes

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Stress Testing

• Large carts (20+ line items)
• Complex product structures
• Multiple rules
• Heavy fact computations

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Next Steps

• Common Patterns - Real-world tested examples
• Troubleshooting - Detailed error solutions
• Performance - Optimization guide