fuel-alert/tests/Unit/Services/Forecasting/Features/FeaturesTest.php

<?php

use App\Services\Forecasting\Features\DeltaUlsdLag;
use App\Services\Forecasting\Features\DeltaUlspLag;
use App\Services\Forecasting\Features\IsPreBankHoliday;
use App\Services\Forecasting\Features\UlspMinusMa8;
use App\Services\Forecasting\Features\WeekOfYearTrig;
use App\Services\Forecasting\WeeklyPumpPriceLoader;
use Carbon\Carbon;
use Illuminate\Foundation\Testing\RefreshDatabase;
use Illuminate\Support\Facades\DB;

uses(RefreshDatabase::class);

function seedRisingTenWeeks(int $base = 14000, int $stepUlsp = 100, int $stepUlsd = 80): void
{
    $start = Carbon::parse('2024-01-01');
    for ($i = 0; $i < 10; $i++) {
        DB::table('weekly_pump_prices')->insert([
            'date' => $start->copy()->addWeeks($i)->toDateString(),
            'ulsp_pence' => $base + ($i * $stepUlsp),
            'ulsd_pence' => 15000 + ($i * $stepUlsd),
            'ulsp_duty_pence' => 5295,
            'ulsd_duty_pence' => 5295,
            'ulsp_vat_pct' => 20,
            'ulsd_vat_pct' => 20,
        ]);
    }
}

it('DeltaUlspLag(0) returns ULSP[t-7d] − ULSP[t-14d]', function () {
    seedRisingTenWeeks();
    $loader = new WeeklyPumpPriceLoader;
    $feature = new DeltaUlspLag($loader, lag: 0);

    // Target = 2024-02-26 → t-7d = 2024-02-19 (ulsp=14700), t-14d = 2024-02-12 (14600).
    $value = $feature->valueFor(Carbon::parse('2024-02-26'));
    expect($value)->toBe(100.0);
});

it('DeltaUlspLag(3) returns ULSP[t-28d] − ULSP[t-35d]', function () {
    seedRisingTenWeeks();
    $loader = new WeeklyPumpPriceLoader;
    $feature = new DeltaUlspLag($loader, lag: 3);

    // Target = 2024-03-04 → t-28d = 2024-02-05 (14500), t-35d = 2024-01-29 (14400).
    $value = $feature->valueFor(Carbon::parse('2024-03-04'));
    expect($value)->toBe(100.0);
});

it('DeltaUlspLag returns null when underlying data is missing', function () {
    seedRisingTenWeeks();
    $loader = new WeeklyPumpPriceLoader;
    $feature = new DeltaUlspLag($loader, lag: 0);

    // Target before any seeded data → both lookups miss.
    $value = $feature->valueFor(Carbon::parse('2017-01-01'));
    expect($value)->toBeNull();
});

it('DeltaUlspLag source dates are strictly before target', function () {
    $loader = new WeeklyPumpPriceLoader;
    $feature = new DeltaUlspLag($loader, lag: 0);

    $target = Carbon::parse('2024-06-03');
    $sources = $feature->sourceDates($target);
    foreach ($sources as $s) {
        expect($s->lessThan($target))->toBeTrue();
    }
});

it('DeltaUlsdLag(0) returns ULSD difference for the previous week', function () {
    seedRisingTenWeeks();
    $loader = new WeeklyPumpPriceLoader;
    $feature = new DeltaUlsdLag($loader, lag: 0);

    // Diesel rises by 80 each week. lag 0 = t-7 minus t-14.
    $value = $feature->valueFor(Carbon::parse('2024-02-26'));
    expect($value)->toBe(80.0);
});

it('UlspMinusMa8 returns the gap between latest and 8-week mean', function () {
    seedRisingTenWeeks();
    $loader = new WeeklyPumpPriceLoader;
    $feature = new UlspMinusMa8($loader);

    // Target = 2024-03-04. Window = 2024-02-26 (latest) ... 2024-01-08 (oldest).
    // Values: 14800, 14700, 14600, 14500, 14400, 14300, 14200, 14100.
    // Latest = 14800, mean = 14450. Gap = 350.
    $value = $feature->valueFor(Carbon::parse('2024-03-04'));
    expect($value)->toBe(350.0);
});

it('UlspMinusMa8 returns null when 8-week window is incomplete', function () {
    seedRisingTenWeeks();
    $loader = new WeeklyPumpPriceLoader;
    $feature = new UlspMinusMa8($loader);

    // Target only has 1 week of history before it.
    $value = $feature->valueFor(Carbon::parse('2024-01-08'));
    expect($value)->toBeNull();
});

it('UlspMinusMa8 source dates are 8 weeks back, all before target', function () {
    $loader = new WeeklyPumpPriceLoader;
    $feature = new UlspMinusMa8($loader);

    $target = Carbon::parse('2024-06-03');
    $sources = $feature->sourceDates($target);
    expect($sources)->toHaveCount(8);
    foreach ($sources as $s) {
        expect($s->lessThan($target))->toBeTrue();
    }
});

it('WeekOfYearTrig returns sin/cos values bounded by [-1,1]', function () {
    $sin = new WeekOfYearTrig('sin');
    $cos = new WeekOfYearTrig('cos');

    foreach (['2024-01-01', '2024-04-15', '2024-07-29', '2024-12-30'] as $d) {
        $sv = $sin->valueFor(Carbon::parse($d));
        $cv = $cos->valueFor(Carbon::parse($d));
        expect($sv)->toBeGreaterThanOrEqual(-1.0)->toBeLessThanOrEqual(1.0)
            ->and($cv)->toBeGreaterThanOrEqual(-1.0)->toBeLessThanOrEqual(1.0);
    }
});

it('WeekOfYearTrig source dates are empty (calendar feature)', function () {
    $feature = new WeekOfYearTrig('sin');
    expect($feature->sourceDates(Carbon::parse('2024-06-03')))->toBe([]);
});

it('WeekOfYearTrig rejects unknown components', function () {
    new WeekOfYearTrig('tan');
})->throws(InvalidArgumentException::class);

it('IsPreBankHoliday is 1.0 when a UK bank holiday is in the next 7 days', function () {
    $feature = new IsPreBankHoliday;
    // 2024-04-01 is Easter Monday → that week itself contains a holiday.
    expect($feature->valueFor(Carbon::parse('2024-04-01')))->toBe(1.0);
});

it('IsPreBankHoliday is 0.0 in a quiet stretch', function () {
    $feature = new IsPreBankHoliday;
    expect($feature->valueFor(Carbon::parse('2024-07-15')))->toBe(0.0);
});