[IMP] product_margin: Replace yml test by a meaningful python test

Purpose
=======

The original yml doesn't test anything except a read on the related fields.

Specification
=============

Replace the test by a python test that compares the values with the expected ones.

addons/product_margin/__manifest__.py

@@ -17,5 +17,4 @@ The wizard to launch the report has several options to help you get the data you
         'wizard/product_margin_view.xml',
         'views/product_product_views.xml'
     ],
-    'test': ['test/product_margin.yml'],
 }

addons/product_margin/test/product_margin.yml

@@ -1,25 +0,0 @@
--
-   In order to test the product_margin module, I create a product margin record
--
-  !record {model: product.margin, id: product_margin_wiz0}:
-    from_date: !eval "'%s-01-01' %(datetime.now().year)"
-    to_date: !eval "'%s-12-31' %(datetime.now().year)"
-    invoice_state: open_paid
--
-  I open margin for PC-DEM
--
-  !python {model: product.margin, id: False}: |
-    self.browse(ref('product_margin_wiz0')).with_context({"lang": 'en_US',
-      "search_default_filter_to_sell": "1", "tz": False, "active_model": "product.product", "disable_log": True, 
-      "active_ids": [ref("product.product_product_5")], "active_id": ref("product.product_product_5")}).action_open_window()
--
-  I read the fields of the product.
--
-  !python {model: product.product, id: False}: |
-    fields = ['sale_avg_price', 'expected_margin_rate', 'total_margin_rate', 'total_cost', 'sale_num_invoiced', 
-      'total_margin', 'sales_gap', 'purchase_num_invoiced', 'expected_margin', 'turnover']
-    self.browse(ref('product_margin_wiz0')).with_context({"lang": 'en_US',
-      "search_default_filter_to_sell": "1", "tz": False, "active_model": "product.product", 
-      "bin_size": True, "active_ids": [ref("product.product_product_5")], 
-      "active_id": ref("product.product_product_5")}).read(fields)
-

addons/product_margin/tests/__init__.py

@@ -0,0 +1,4 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+from . import test_product_margin

addons/product_margin/tests/test_product_margin.py

@@ -0,0 +1,72 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+from odoo import tools
+from odoo.tests import common
+from odoo.modules.module import get_resource_path
+
+
+class TestProductMargin(common.TransactionCase):
+
+    def create_account_invoice(self, invoice_type, partner, product, quantity=0.0, price_unit=0.0):
+        """ Create an invoice as in a view by triggering its onchange methods"""
+        default_get_vals = self.env['account.invoice'].default_get(list(self.env['account.invoice'].fields_get()))
+        account_invoice = self.env['account.invoice'].new(default_get_vals)
+        account_invoice.type = invoice_type
+        account_invoice._onchange_journal_id()
+        account_invoice.partner_id = partner.id
+        account_invoice._onchange_partner_id()
+        account_invoice.invoice_line_ids = [(0, 0, {
+            'quantity': quantity,
+            'product_id': product.id,
+            'uom_id': self.ref('product.product_uom_unit'),
+            'invoice_id': account_invoice,  # This value is required for '_onchange_product_id' to work correctly
+        })]
+        account_invoice.invoice_line_ids._onchange_product_id()
+        account_invoice.invoice_line_ids.price_unit = price_unit
+        account_invoice._onchange_invoice_line_ids()
+        vals = account_invoice._convert_to_write(account_invoice._cache)
+        account_invoice = self.env['account.invoice'].create(vals)
+        account_invoice.action_invoice_open()
+
+    def test_product_margin(self):
+        ''' In order to test the product_margin module '''
+
+        # load account_minimal_test.xml file for chart of account in configuration
+        tools.convert_file(self.cr, 'product_margin',
+                           get_resource_path('account', 'test', 'account_minimal_test.xml'),
+                           {}, 'init', False, 'test', self.registry._assertion_report)
+
+        supplier = self.env['res.partner'].create({'name': 'Supplier', 'supplier': True})
+        customer = self.env['res.partner'].create({'name': 'Customer', 'customer': True})
+        ipad = self.env.ref("product.product_product_4")
+
+        # Create supplier invoice and customer invoice to test product margin.
+        # Define supplier invoices
+        self.create_account_invoice('in_invoice', supplier, ipad, 10.0, 300.00)
+        self.create_account_invoice('in_invoice', supplier, ipad, 4.0, 450.00)
+        # Define Customer Invoices
+        self.create_account_invoice('out_invoice', customer, ipad, 20.0, 750.00)
+        self.create_account_invoice('out_invoice', customer, ipad, 10.0, 550.00)
+
+        result = ipad._compute_product_margin_fields_values()
+
+        # Sale turnover ( Quantity * Price Subtotal / Quantity)
+        sale_turnover = ((20.0 * 750.00) + (10.0 * 550.00))
+
+        # Expected sale (Total quantity * Sale price)
+        sale_expected = (750.00 * 30.0)
+
+        # Purchase total cost (Quantity * Unit price)
+        purchase_total_cost = ((10.0 * 300.00) + (4.0 * 450.00))
+
+        # Purchase normal cost ( Total quantity * Cost price)
+        purchase_normal_cost = (14.0 * 500.00)
+
+        total_margin = sale_turnover - purchase_total_cost
+        expected_margin = sale_expected - purchase_normal_cost
+
+        # Check total margin
+        self.assertEqual(result[ipad.id]['total_margin'], total_margin, "Wrong Total Margin.")
+
+        # Check expected margin
+        self.assertEqual(result[ipad.id]['expected_margin'], expected_margin, "Wrong Expected Margin.")