Add automated tests for the 25% pricing formula and $25/$15 shipping thresholds

Launch gate (design doc §5/§8) requires automated tests for both; the repo
had zero test infra until now. PHPUnit + Brain Monkey, run via `make test`
against the existing wordpress dev container.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MqhgnCRjjVLFnZ3Jpn93Vg

wp-content/plugins/bookstore-core/tests/TestCase.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace Bookstore\Core\Tests;
+
+use Brain\Monkey;
+use PHPUnit\Framework\TestCase as PHPUnitTestCase;
+
+abstract class TestCase extends PHPUnitTestCase
+{
+    protected function setUp(): void
+    {
+        parent::setUp();
+        Monkey\setUp();
+    }
+
+    protected function tearDown(): void
+    {
+        Monkey\tearDown();
+        parent::tearDown();
+    }
+}

wp-content/plugins/bookstore-core/tests/Unit/Pricing/PricingEngineTest.php

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+<?php
+
+namespace Bookstore\Core\Tests\Unit\Pricing;
+
+use Bookstore\Core\Pricing\PricingEngine;
+use Bookstore\Core\Tests\TestCase;
+
+/**
+ * Launch gate: "25% pricing logic ... have automated tests" (design doc
+ * §5/§8). calculate_retail_price()/round_to_99()/estimate_processing_cost()
+ * are pure math with no WordPress/WooCommerce dependency, so no mocking
+ * is needed here.
+ */
+class PricingEngineTest extends TestCase
+{
+    /**
+     * @dataProvider retailPriceCases
+     */
+    public function test_calculate_retail_price_applies_25_percent_margin_formula(
+        float $supplier_base,
+        float $supplier_shipping,
+        float $expected
+    ): void {
+        $actual = PricingEngine::calculate_retail_price($supplier_base, $supplier_shipping);
+        $this->assertEqualsWithDelta($expected, $actual, 0.001);
+    }
+
+    public static function retailPriceCases(): array
+    {
+        return [
+            'small order' => [10.00, 3.00, 18.99],
+            'no supplier shipping' => [5.00, 0.00, 7.99],
+            'near a .99 boundary' => [14.20, 0.05, 20.99],
+            'zero supplier cost still covers fixed processing' => [0.00, 0.00, 0.99],
+            'larger order' => [100.00, 10.00, 152.99],
+        ];
+    }
+
+    /**
+     * @dataProvider roundTo99Cases
+     */
+    public function test_round_to_99_never_rounds_below_the_input(float $price, float $expected): void
+    {
+        $this->assertEqualsWithDelta($expected, PricingEngine::round_to_99($price), 0.001);
+    }
+
+    public static function roundTo99Cases(): array
+    {
+        return [
+            // The case the class's own docblock calls out: the old
+            // ceil($price) - 0.01 formula gave 20.99 here, which is
+            // below the $20.995 input and would erode the target margin.
+            'fractional price above the X.99 ending' => [20.995, 21.99],
+            'exact integer input' => [18.00, 18.99],
+            'already exactly X.99' => [7.99, 7.99],
+            'just above X.99' => [8.00, 8.99],
+        ];
+    }
+
+    public function test_estimate_processing_cost(): void
+    {
+        $this->assertEqualsWithDelta(0.83, PricingEngine::estimate_processing_cost(20.99), 0.001);
+        $this->assertEqualsWithDelta(3.00, PricingEngine::estimate_processing_cost(100.00), 0.001);
+    }
+}

wp-content/plugins/bookstore-core/tests/Unit/Shipping/BSCFreeShippingTest.php

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+<?php
+
+namespace Bookstore\Core\Tests\Unit\Shipping;
+
+use Bookstore\Core\Shipping\BSC_Free_Shipping;
+use Bookstore\Core\Tests\TestCase;
+use Brain\Monkey\Functions;
+use Mockery;
+
+/**
+ * Launch gate: "$25/$15 shipping thresholds have automated tests" (design
+ * doc §5/§8). threshold_for_current_customer() reads membership via a raw
+ * $wpdb query and thresholds via get_option() (with the $25/$15 launch
+ * numbers as the fallback defaults) — both are stubbed here rather than
+ * hitting WordPress/a real database. The class's own docblock says
+ * thresholds are option-backed "so the launch gate's automated test can
+ * assert against the same source this reads from" — the last test below
+ * proves exactly that.
+ */
+class BSCFreeShippingTest extends TestCase
+{
+    protected function tearDown(): void
+    {
+        global $wpdb;
+        $wpdb = null;
+        parent::tearDown();
+    }
+
+    public function test_guest_gets_default_25_dollar_threshold(): void
+    {
+        Functions\when('get_current_user_id')->justReturn(0);
+        Functions\when('get_option')->alias(fn($name, $default) => $default);
+
+        $this->assertSame(25.00, BSC_Free_Shipping::threshold_for_current_customer());
+    }
+
+    public function test_logged_in_non_member_gets_default_25_dollar_threshold(): void
+    {
+        Functions\when('get_current_user_id')->justReturn(42);
+        Functions\when('get_option')->alias(fn($name, $default) => $default);
+        $this->mock_wpdb_is_free_member(false);
+
+        $this->assertSame(25.00, BSC_Free_Shipping::threshold_for_current_customer());
+    }
+
+    public function test_free_member_gets_15_dollar_threshold(): void
+    {
+        Functions\when('get_current_user_id')->justReturn(7);
+        Functions\when('get_option')->alias(fn($name, $default) => $default);
+        $this->mock_wpdb_is_free_member(true);
+
+        $this->assertSame(15.00, BSC_Free_Shipping::threshold_for_current_customer());
+    }
+
+    public function test_custom_option_override_is_respected_not_the_hardcoded_default(): void
+    {
+        Functions\when('get_current_user_id')->justReturn(0);
+        Functions\expect('get_option')
+            ->once()
+            ->with('bsc_shipping_threshold_guest', 25.00)
+            ->andReturn(29.99);
+
+        $this->assertSame(29.99, BSC_Free_Shipping::threshold_for_current_customer());
+    }
+
+    private function mock_wpdb_is_free_member(bool $is_member): void
+    {
+        global $wpdb;
+        $wpdb = Mockery::mock('wpdb');
+        $wpdb->prefix = 'wp_';
+        $wpdb->shouldReceive('prepare')->once()->andReturn('SELECT is_free_member ...');
+        $wpdb->shouldReceive('get_var')->once()->andReturn($is_member ? '1' : '0');
+    }
+}

wp-content/plugins/bookstore-core/tests/bootstrap.php

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+<?php
+
+/**
+ * Unit-test bootstrap: pure PHPUnit + Brain Monkey, not a full WordPress
+ * bootstrap. includes/*.php all guard on `defined('ABSPATH') || exit;`
+ * at file-load time, and BSC_Free_Shipping extends \WC_Shipping_Method
+ * (a WooCommerce core class) — both need to exist before Composer's
+ * autoloader ever pulls those files in, hence defining/stubbing them
+ * here rather than per test case.
+ */
+
+require __DIR__ . '/../vendor/autoload.php';
+
+if (!defined('ABSPATH')) {
+    define('ABSPATH', __DIR__ . '/');
+}
+
+if (!class_exists(\WC_Shipping_Method::class)) {
+    class WC_Shipping_Method
+    {
+    }
+}