Anade tests de regresion del dashboard

La vista dashboard concentra los presets de periodo, el filtro por cuenta,
la comparativa y las series de las graficas, y solo tenia cubierto el
filtro por ano. Antes de tocarla conviene fijar por escrito lo que hace
hoy, para que el refactor que viene no pueda cambiarlo sin que salte algo.

Cubre los tres presets (this_month, last_month, this_year), el filtro por
cuenta con su KPI de saldo, los valores por defecto de la comparativa
cuando no esta activada, la diferencia y la tendencia cuando si lo esta,
el chart_type segun se mire un mes o el ano entero, y el recorte a diez
categorias de la grafica de distribucion.

El test de la grafica de categorias comprueba tambien que by_category
sigue trayendo las doce: el recorte es solo de la grafica, no del listado.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

expenses_manager/expenses/tests/test_dashboard.py

@@ -2,7 +2,7 @@ import pytest
 from datetime import date
 from decimal import Decimal
 from django.urls import reverse
-from expenses.models import Expense, Category
+from expenses.models import Account, Expense, Category, Income
 
 pytestmark = pytest.mark.django_db
 
@@ -80,3 +80,146 @@ def test_dashboard_filters_by_year(auth_client, user, account, category):
     assert len(chart_data) == 12
     assert chart_data[4] == 20.0  # May = month 5 -> index 4
     assert sum(chart_data) == 20.0  # only the 2024 expense contributes
+
+
+def test_dashboard_preset_this_month(auth_client):
+    today = date.today()
+
+    response = auth_client.get(reverse('dashboard'), {'period': 'this_month'})
+
+    assert response.context['selected_year'] == today.year
+    assert response.context['selected_month'] == today.month
+
+
+def test_dashboard_preset_last_month(auth_client):
+    today = date.today()
+    expected_month = today.month - 1 or 12
+    expected_year = today.year if today.month > 1 else today.year - 1
+
+    response = auth_client.get(reverse('dashboard'), {'period': 'last_month'})
+
+    assert response.context['selected_year'] == expected_year
+    assert response.context['selected_month'] == expected_month
+
+
+def test_dashboard_preset_this_year_has_no_month(auth_client):
+    today = date.today()
+
+    response = auth_client.get(reverse('dashboard'), {'period': 'this_year'})
+
+    assert response.context['selected_year'] == today.year
+    assert response.context['selected_month'] is None
+
+
+def test_dashboard_filters_by_account(auth_client, user, account, category):
+    other = Account.objects.create(
+        owner=user, name="Otra", initial_balance=Decimal("100"), active=True
+    )
+    Expense.objects.create(
+        owner=user, account=account, category=category,
+        amount=Decimal("10"), date=date(2024, 3, 1),
+    )
+    Expense.objects.create(
+        owner=user, account=other, category=category,
+        amount=Decimal("25"), date=date(2024, 3, 1),
+    )
+
+    response = auth_client.get(
+        reverse('dashboard'),
+        {'year': 2024, 'account': other.id},
+    )
+
+    assert response.context['kpi_total'] == Decimal('25')
+    assert response.context['kpi_count'] == 1
+    assert response.context['kpi_balance'] == Decimal('75')  # 100 - 25
+
+
+def test_dashboard_without_compare_keeps_comparison_defaults(auth_client):
+    response = auth_client.get(reverse('dashboard'), {'year': 2024})
+
+    assert response.context['compare_enabled'] is False
+    assert response.context['kpi_previous_total'] == 0
+    assert response.context['kpi_difference'] == 0
+    assert response.context['kpi_percentage'] == 0
+    assert response.context['kpi_trend'] == 'equal'
+    assert response.context['category_comparison'] == []
+
+
+def test_dashboard_compare_fills_difference_and_trend(auth_client, user, account, category):
+    Expense.objects.create(
+        owner=user, account=account, category=category,
+        amount=Decimal("20"), date=date(2024, 2, 15),
+    )
+    Expense.objects.create(
+        owner=user, account=account, category=category,
+        amount=Decimal("30"), date=date(2024, 3, 10),
+    )
+
+    response = auth_client.get(
+        reverse('dashboard'),
+        {'year': 2024, 'month': 3, 'compare': '1'},
+    )
+
+    assert response.context['compare_enabled'] is True
+    assert response.context['kpi_previous_total'] == Decimal('20')
+    assert response.context['kpi_difference'] == Decimal('10')
+    assert response.context['kpi_trend'] == 'up'
+    assert float(response.context['kpi_percentage']) == 50.0
+
+    rows = {row['category']: row for row in response.context['category_comparison']}
+    assert rows[category.name]['current'] == 30.0
+    assert rows[category.name]['previous'] == 20.0
+    assert rows[category.name]['difference'] == 10.0
+
+
+def test_dashboard_chart_type_is_day_when_a_month_is_selected(auth_client):
+    response = auth_client.get(reverse('dashboard'), {'year': 2024, 'month': 3})
+
+    assert response.context['chart_type'] == 'day'
+
+
+def test_dashboard_chart_type_is_month_for_the_whole_year(auth_client):
+    response = auth_client.get(reverse('dashboard'), {'year': 2024})
+
+    assert response.context['chart_type'] == 'month'
+
+
+def test_dashboard_category_chart_keeps_only_top_ten(auth_client, user, account):
+    for i in range(12):
+        cat = Category.objects.create(name=f"Cat {i:02d}", owner=user)
+        Expense.objects.create(
+            owner=user, account=account, category=cat,
+            amount=Decimal(str(i + 1)), date=date(2024, 6, 1),
+        )
+
+    response = auth_client.get(reverse('dashboard'), {'year': 2024})
+
+    assert len(response.context['by_category_chart']) == 10
+    assert len(list(response.context['by_category'])) == 12
+
+
+def test_dashboard_kpi_balance_matches_sum_of_current_balances(auth_client, user, account, category):
+    savings = Account.objects.create(
+        owner=user, name="Ahorro", initial_balance=Decimal("500"), active=True
+    )
+    Account.objects.create(
+        owner=user, name="Cerrada", initial_balance=Decimal("999"), active=False
+    )
+
+    Expense.objects.create(
+        owner=user, account=account, category=category,
+        amount=Decimal("40"), date=date(2024, 4, 1),
+    )
+    Income.objects.create(
+        owner=user, account=savings, name="Nomina",
+        amount=Decimal("60"), date=date(2024, 4, 2),
+    )
+
+    response = auth_client.get(reverse('dashboard'), {'year': 2024})
+
+    expected = sum(
+        acc.current_balance()
+        for acc in Account.objects.filter(owner=user, active=True)
+    )
+    assert expected == Decimal('520')  # (0 - 40) + (500 + 60), sin la inactiva
+    assert response.context['kpi_balance'] == expected