From cc666a3111833bc6581b46e6f46247f6f9ed7ce1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?V=C3=ADctor=20Falc=C3=B3n?= <victoor89@gmail.com>
Date: Sat, 31 Jan 2026 14:38:17 +0100
Subject: [PATCH] test: Fix Carbon month overflow in date calculations (#87)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

## Summary
- Replace `subMonths()` with `subMonthsNoOverflow()` across controllers,
commands, and tests to prevent date overflow on months with 31 days
- On Jan 31, `subMonths(2)` overflows: Nov 31 doesn't exist → Carbon
rolls forward to Dec 1, producing wrong date ranges and off-by-one month
counts

## Root cause
Carbon's `subMonths()` allows day overflow. When the target month has
fewer days than the source date, it rolls into the next month. For
example:
- `2026-01-31 subMonths(2)` → Nov 31 → **2025-12-01** (expected Nov 30)
- `2026-01-31 subMonths(11)` → Feb 31 → **2025-03-03** (expected Feb 28)

`subMonthsNoOverflow()` clamps to the last valid day of the target month
instead.

## Files changed
- `app/Http/Controllers/Api/CashflowAnalyticsController.php` — cashflow
trend start date calculation
- `app/Console/Commands/ResetDemoAccountCommand.php` — balance history
date generation (was causing duplicate `balance_date` entries)
- `tests/Feature/AccountControllerTest.php` — balance evolution `from`
param
- `tests/Feature/CashflowAnalyticsTest.php` — transaction date
generation in loop
- `tests/Feature/DashboardAnalyticsTest.php` — net worth evolution
`from` param

## Test plan
- [x] `account balance evolution returns data` — expects 3 months, was
getting 2
- [x] `cashflow trend returns monthly data` — expects 3 months, was
getting 2
- [x] `cashflow trend defaults to 12 months` — expects 12 months, was
getting 11
- [x] `net worth evolution returns monthly data points` — expects 3
months, was getting 2
- [x] `demo:reset creates demo user` — was throwing
UniqueConstraintViolation on duplicate balance dates
---
 app/Console/Commands/ResetDemoAccountCommand.php         | 2 +-
 app/Http/Controllers/Api/CashflowAnalyticsController.php | 2 +-
 tests/Feature/AccountControllerTest.php                  | 2 +-
 tests/Feature/CashflowAnalyticsTest.php                  | 4 ++--
 tests/Feature/DashboardAnalyticsTest.php                 | 2 +-
 5 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/app/Console/Commands/ResetDemoAccountCommand.php b/app/Console/Commands/ResetDemoAccountCommand.php
index 1bf78583..604a3653 100644
--- a/app/Console/Commands/ResetDemoAccountCommand.php
+++ b/app/Console/Commands/ResetDemoAccountCommand.php
@@ -276,7 +276,7 @@ class ResetDemoAccountCommand extends Command
         $balances = [];
 
         for ($i = 0; $i <= 12; $i++) {
-            $date = now()->subMonths($i)->endOfMonth();
+            $date = now()->subMonthsNoOverflow($i)->endOfMonth();
 
             if ($i === 0) {
                 $date = now();
diff --git a/app/Http/Controllers/Api/CashflowAnalyticsController.php b/app/Http/Controllers/Api/CashflowAnalyticsController.php
index 99dfe7a1..ed24ac44 100644
--- a/app/Http/Controllers/Api/CashflowAnalyticsController.php
+++ b/app/Http/Controllers/Api/CashflowAnalyticsController.php
@@ -67,7 +67,7 @@ class CashflowAnalyticsController extends Controller
         $userId = $request->user()->id;
 
         $end = Carbon::now()->endOfMonth();
-        $start = Carbon::now()->subMonths($months - 1)->startOfMonth();
+        $start = Carbon::now()->subMonthsNoOverflow($months - 1)->startOfMonth();
 
         $data = [];
         $current = $start->copy();
diff --git a/tests/Feature/AccountControllerTest.php b/tests/Feature/AccountControllerTest.php
index 98fb1cad..366b7113 100644
--- a/tests/Feature/AccountControllerTest.php
+++ b/tests/Feature/AccountControllerTest.php
@@ -167,7 +167,7 @@ test('account balance evolution returns data for single account', function () {
     ]);
 
     $response = $this->getJson('/api/dashboard/account/'.$account->id.'/balance-evolution?'.http_build_query([
-        'from' => now()->subMonths(2)->startOfMonth()->toDateString(),
+        'from' => now()->subMonthsNoOverflow(2)->startOfMonth()->toDateString(),
         'to' => now()->endOfMonth()->toDateString(),
     ]));
 
diff --git a/tests/Feature/CashflowAnalyticsTest.php b/tests/Feature/CashflowAnalyticsTest.php
index 2dec35bb..bc6432bb 100644
--- a/tests/Feature/CashflowAnalyticsTest.php
+++ b/tests/Feature/CashflowAnalyticsTest.php
@@ -223,14 +223,14 @@ test('cashflow trend returns monthly data for specified months', function () {
             'account_id' => $account->id,
             'category_id' => $incomeCategory->id,
             'amount' => 100000 + ($i * 10000),
-            'transaction_date' => now()->subMonths($i),
+            'transaction_date' => now()->subMonthsNoOverflow($i),
         ]);
         Transaction::factory()->create([
             'user_id' => $this->user->id,
             'account_id' => $account->id,
             'category_id' => $expenseCategory->id,
             'amount' => -(50000 + ($i * 5000)),
-            'transaction_date' => now()->subMonths($i),
+            'transaction_date' => now()->subMonthsNoOverflow($i),
         ]);
     }
 
diff --git a/tests/Feature/DashboardAnalyticsTest.php b/tests/Feature/DashboardAnalyticsTest.php
index 108d72f7..78c2c3a1 100644
--- a/tests/Feature/DashboardAnalyticsTest.php
+++ b/tests/Feature/DashboardAnalyticsTest.php
@@ -211,7 +211,7 @@ test('net worth evolution returns monthly data points with per-account balances'
     ]);
 
     $response = $this->getJson('/api/dashboard/net-worth-evolution?'.http_build_query([
-        'from' => now()->subMonths(2)->startOfMonth()->toDateString(),
+        'from' => now()->subMonthsNoOverflow(2)->startOfMonth()->toDateString(),
         'to' => now()->endOfMonth()->toDateString(),
     ]));