feat(fusion_accounting_assets): prorate service for partial-period depreciation

Made-with: Cursor

fusion_accounting_assets/__manifest__.py

@@ -1,6 +1,6 @@
 {
     'name': 'Fusion Accounting Assets',
-    'version': '19.0.1.0.1',
+    'version': '19.0.1.0.2',
     'category': 'Accounting/Accounting',
     'summary': 'AI-augmented asset management with depreciation schedules.',
     'description': """

fusion_accounting_assets/services/__init__.py

@@ -1 +1,2 @@
 from . import depreciation_methods
+from . import prorate

fusion_accounting_assets/services/prorate.py

@@ -0,0 +1,34 @@
+"""Prorating helpers for first-period and last-period depreciation.
+
+When an asset starts mid-month, the first period charges only a fraction
+of the full period_amount. Three conventions:
+- 'full_month': always charge full month (no proration)
+- 'days_365': pro-rate by actual days / 365
+- 'days_period': pro-rate by actual days in period / total days in period
+"""
+
+from datetime import date
+from typing import Literal
+
+
+ProrateConvention = Literal['full_month', 'days_365', 'days_period']
+
+
+def prorate_factor(*, period_start: date, period_end: date,
+                   asset_start: date,
+                   convention: ProrateConvention = 'days_period') -> float:
+    """Return a 0..1 factor for how much of `period`'s depreciation
+    applies to an asset that started on `asset_start`."""
+    if convention == 'full_month':
+        return 1.0
+    if asset_start <= period_start:
+        return 1.0
+    if asset_start > period_end:
+        return 0.0
+    actual_days = (period_end - asset_start).days + 1
+    if convention == 'days_365':
+        return actual_days / 365.0
+    if convention == 'days_period':
+        period_days = (period_end - period_start).days + 1
+        return actual_days / period_days
+    raise ValueError(f"Unknown convention: {convention}")

fusion_accounting_assets/tests/__init__.py

@@ -1 +1,2 @@
 from . import test_depreciation_methods
+from . import test_prorate

fusion_accounting_assets/tests/test_prorate.py

@@ -0,0 +1,65 @@
+from datetime import date
+
+from odoo.tests.common import TransactionCase
+from odoo.tests import tagged
+from odoo.addons.fusion_accounting_assets.services.prorate import prorate_factor
+
+
+@tagged('post_install', '-at_install')
+class TestProrate(TransactionCase):
+
+    def test_full_month_convention_always_one(self):
+        f = prorate_factor(
+            period_start=date(2026, 1, 1),
+            period_end=date(2026, 1, 31),
+            asset_start=date(2026, 1, 15),
+            convention='full_month',
+        )
+        self.assertEqual(f, 1.0)
+
+    def test_asset_starts_before_period_full_factor(self):
+        f = prorate_factor(
+            period_start=date(2026, 1, 1),
+            period_end=date(2026, 1, 31),
+            asset_start=date(2025, 12, 1),
+            convention='days_period',
+        )
+        self.assertEqual(f, 1.0)
+
+    def test_asset_starts_after_period_zero_factor(self):
+        f = prorate_factor(
+            period_start=date(2026, 1, 1),
+            period_end=date(2026, 1, 31),
+            asset_start=date(2026, 2, 5),
+            convention='days_period',
+        )
+        self.assertEqual(f, 0.0)
+
+    def test_days_period_mid_month(self):
+        # Jan 16 -> Jan 31 inclusive = 16 days; period = 31 days
+        f = prorate_factor(
+            period_start=date(2026, 1, 1),
+            period_end=date(2026, 1, 31),
+            asset_start=date(2026, 1, 16),
+            convention='days_period',
+        )
+        self.assertAlmostEqual(f, 16 / 31, places=5)
+
+    def test_days_365_mid_month(self):
+        # 16 days / 365
+        f = prorate_factor(
+            period_start=date(2026, 1, 1),
+            period_end=date(2026, 1, 31),
+            asset_start=date(2026, 1, 16),
+            convention='days_365',
+        )
+        self.assertAlmostEqual(f, 16 / 365.0, places=5)
+
+    def test_unknown_convention_raises(self):
+        with self.assertRaises(ValueError):
+            prorate_factor(
+                period_start=date(2026, 1, 1),
+                period_end=date(2026, 1, 31),
+                asset_start=date(2026, 1, 15),
+                convention='bogus',  # type: ignore[arg-type]
+            )