math_cms/tests/Unit/DifficultyDistributionServiceTest.php

<?php

namespace Tests\Unit;

use App\Services\DifficultyDistributionService;
use App\Services\LearningAnalyticsService;
use ReflectionClass;
use Tests\TestCase;

class DifficultyDistributionServiceTest extends TestCase
{
    public function test_category_three_distribution_keeps_only_ten_percent_low_band(): void
    {
        $service = new DifficultyDistributionService();

        $distribution = $service->calculateDistribution(3, 10);

        $this->assertSame(1, $distribution['low']['count']);
        $this->assertSame(8, $distribution['medium']['count']);
        $this->assertSame(1, $distribution['high']['count']);
        $this->assertSame(10, array_sum(array_column($distribution, 'count')));
    }

    public function test_category_three_difficulty_buckets_keep_extreme_low_out_of_target_low_band(): void
    {
        $service = new DifficultyDistributionService();

        $this->assertSame('other', $service->classifyQuestionByDifficulty(0.06, 3));
        $this->assertSame('secondary', $service->classifyQuestionByDifficulty(0.36, 3));
        $this->assertSame('primary_low', $service->classifyQuestionByDifficulty(0.42, 3));
        $this->assertSame('primary_medium', $service->classifyQuestionByDifficulty(0.62, 3));
        $this->assertSame('primary_high', $service->classifyQuestionByDifficulty(0.80, 3));
    }

    public function test_category_three_supplement_order_prefers_higher_difficulty_before_low_fallback(): void
    {
        $service = new DifficultyDistributionService();

        $this->assertSame(
            ['primary_medium', 'primary_high', 'primary_low', 'secondary', 'other'],
            $service->getSupplementOrder(3)
        );
    }

    public function test_category_four_difficulty_buckets_use_split_high_mid_low_ranges(): void
    {
        $service = new DifficultyDistributionService();

        $this->assertSame('secondary', $service->classifyQuestionByDifficulty(0.49, 4));
        $this->assertSame('primary_low', $service->classifyQuestionByDifficulty(0.50, 4));
        $this->assertSame('primary_medium', $service->classifyQuestionByDifficulty(0.80, 4));
        $this->assertSame('primary_high', $service->classifyQuestionByDifficulty(0.92, 4));
    }

    public function test_category_four_supplement_order_prefers_higher_difficulty_first(): void
    {
        $service = new DifficultyDistributionService();

        $this->assertSame(
            ['primary_high', 'primary_medium', 'primary_low', 'secondary', 'other'],
            $service->getSupplementOrder(4)
        );
    }

    public function test_category_three_answer_floor_replaces_low_answer_without_losing_total_count(): void
    {
        $service = app(LearningAnalyticsService::class);
        $reflection = new ReflectionClass($service);
        $method = $reflection->getMethod('enforceAnswerDifficultyFloor');
        $method->setAccessible(true);

        $selected = [
            $this->question(1, 'choice', 0.3),
            $this->question(2, 'fill', 0.4),
            $this->question(3, 'answer', 0.06),
            $this->question(4, 'answer', 0.5),
        ];
        $pool = array_merge($selected, [
            $this->question(5, 'answer', 0.62),
            $this->question(6, 'fill', 0.58),
        ]);

        $result = $method->invoke($service, $pool, $selected, 3, 4);

        $this->assertCount(4, $result);
        $this->assertFalse(collect($result)->contains(
            fn (array $question) => $question['question_type'] === 'answer' && $question['difficulty'] < 0.4
        ));
        $this->assertTrue(collect($result)->contains(
            fn (array $question) => $question['id'] === 5
        ));
    }

    private function question(int $id, string $type, float $difficulty): array
    {
        return [
            'id' => $id,
            'question_type' => $type,
            'difficulty' => $difficulty,
            'stem' => "Question {$id}",
            'kp_code' => 'KP001',
            'solution' => 'solution',
        ];
    }
}