Generate TDD Tests

Generate TDD Tests (Iron Law)

"Write the test first. Watch it fail. Write minimal code to pass."

The Iron Law

NO PRODUCTION CODE WITHOUT A FAILING TEST FIRST.

If you write code before the test: Delete it. Start over. This is non-negotiable.

Red-Green-Refactor Cycle

1. RED: Write Failing Test

Write one minimal test showing what should happen. Use FrappeTestCase.

import frappe
from frappe.tests.utils import FrappeTestCase

class TestSalesOrder(FrappeTestCase):
    def test_status_must_be_draft_on_creation(self):
        # We wish for this behavior
        doc = frappe.get_doc({"doctype": "Sales Order", "customer": "Test Customer"})
        self.assertEqual(doc.status, "Draft")

Verify RED: Run bench --site [site] run-tests --doctype "Sales Order".

• Must Fail: If it passes, you are testing existing behavior. Fix the test.
• Expected Failure: Confirm it fails because doc.status is NOT "Draft".

2. GREEN: Minimal Code

Write the simplest code in the controller (sales_order.py) to pass the test.

class SalesOrder(Document):
    def before_insert(self):
        self.status = "Draft"

Verify GREEN: Run the test again. It must pass.

3. REFACTOR: Clean Up

Clean up duplication, improve names, or extract helpers while keeping the test Green.

Frappe Test Patterns

Validation Tests

def test_customer_is_mandatory(self):
    doc = frappe.get_doc({"doctype": "Sales Order", "customer": None})
    self.assertRaises(frappe.ValidationError, doc.insert)

Permission Tests

def test_regular_user_cannot_submit(self):
    frappe.set_user("[email protected]")
    doc = frappe.get_doc("Sales Order", "SO-001")
    self.assertRaises(frappe.PermissionError, doc.submit)

Mocking (Use only if unavoidable)

Prefer real data using frappe.get_doc. If you must mock external APIs:

from unittest.mock import patch

@patch('frappe.make_get_request')
def test_api_integration(self, mock_get):
    mock_get.return_value = {"status": "success"}
    # ... call your method ...

Anti-Patterns

Checklist

• Every new function has a test.
• Watched each test fail for the right reason.
• Minimal code written to pass.
• tearDown performs rollback or cleanup.
• Edge cases (None, Empty, Invalid) covered.