feat: tag-based product alternatives

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

tests/Feature/ProductAlternativesTest.php

@@ -0,0 +1,99 @@
+<?php
+
+use App\Models\Product;
+use App\Models\Tag;
+use App\Models\Upvote;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Illuminate\Support\Facades\DB;
+
+uses(RefreshDatabase::class);
+
+function altTags(int $n): array
+{
+    return collect(range(1, $n))->map(fn ($i) => Tag::create([
+        'name' => "Alt Tag $i",
+        'slug' => "alt-tag-$i",
+    ]))->all();
+}
+
+function altProduct(array $tags, string $state = 'approved', array $attrs = []): Product
+{
+    $product = Product::factory()->{$state}()->create($attrs);
+    $product->tags()->sync(collect($tags)->pluck('id')->all());
+
+    return $product;
+}
+
+test('orders by shared tags', function () {
+    [$a, $b, $c, $d] = altTags(4);
+    $self = altProduct([$a, $b, $c]);
+    $two = altProduct([$a, $b]);
+    $three = altProduct([$a, $b, $c, $d]);
+    $one = altProduct([$a]);
+
+    $result = $self->alternatives();
+
+    expect($result->pluck('id')->all())->toBe([$three->id, $two->id, $one->id]);
+    expect($result->pluck('shared_tags_count')->map(fn ($v) => (int) $v)->all())->toBe([3, 2, 1]);
+});
+
+test('excludes self, pending, rejected and zero-shared-tag products', function () {
+    [$a, $b] = altTags(2);
+    $self = altProduct([$a]);
+    $good = altProduct([$a]);
+    altProduct([$a], 'pending');
+    altProduct([$a], 'rejected');
+    altProduct([$b]);
+
+    expect($self->alternatives()->pluck('id')->all())->toBe([$good->id]);
+});
+
+test('ties are ordered by upvotes then newest', function () {
+    [$a] = altTags(1);
+    $self = altProduct([$a]);
+    $old = altProduct([$a], 'approved', ['created_at' => now()->subDays(3)]);
+    $new = altProduct([$a], 'approved', ['created_at' => now()->subDay()]);
+    $voted = altProduct([$a], 'approved', ['created_at' => now()->subDays(5)]);
+    Upvote::create(['product_id' => $voted->id, 'user_id' => userWithRole('user')->id]);
+
+    expect($self->alternatives()->pluck('id')->all())->toBe([$voted->id, $new->id, $old->id]);
+});
+
+test('limits to 3', function () {
+    [$a] = altTags(1);
+    $self = altProduct([$a]);
+    foreach (range(1, 5) as $i) {
+        altProduct([$a]);
+    }
+
+    expect($self->alternatives())->toHaveCount(3);
+    expect($self->alternatives(2))->toHaveCount(2);
+});
+
+test('alternatives is a single query', function () {
+    [$a, $b] = altTags(2);
+    $self = altProduct([$a, $b]);
+    altProduct([$a]);
+    altProduct([$b]);
+
+    DB::enableQueryLog();
+    $self->alternatives();
+    expect(DB::getQueryLog())->toHaveCount(1);
+});
+
+test('show page renders alternative cards and hides the section when none', function () {
+    [$a] = altTags(1);
+    $self = altProduct([$a]);
+
+    $this->get(route('products.show', $self))->assertOk()->assertDontSee('data-alternatives', false);
+
+    $alt = altProduct([$a], 'approved', ['title' => 'Cool Alternative', 'eu_made' => true]);
+
+    $this->get(route('products.show', $self))
+        ->assertOk()
+        ->assertSee('data-alternatives', false)
+        ->assertSee('Cool Alternative')
+        ->assertSee(route('products.show', $alt), false)
+        ->assertSee('1 shared tag')
+        ->assertSee('EU made');
+});