feat: add NullDriver

tests/Unit/Drivers/NullDriverTest.php

@@ -0,0 +1,62 @@
+<?php
+
+use Wearepixel\Cart\Drivers\NullDriver;
+
+describe('NullDriver', function () {
+    beforeEach(function () {
+        $this->driver = new NullDriver('test-session');
+    });
+
+    test('returns its session key', function () {
+        expect($this->driver->getSessionKey())->toBe('test-session');
+    });
+
+    test('returns null as driver name', function () {
+        expect($this->driver->getDriverName())->toBe('null');
+    });
+
+    test('starts with empty items', function () {
+        expect($this->driver->getItems())->toBe([]);
+    });
+
+    test('stores and retrieves items', function () {
+        $this->driver->putItems([['id' => 1, 'name' => 'Widget']]);
+        expect($this->driver->getItems())->toBe([['id' => 1, 'name' => 'Widget']]);
+    });
+
+    test('starts with empty conditions', function () {
+        expect($this->driver->getConditions())->toBe([]);
+    });
+
+    test('stores and retrieves conditions', function () {
+        $this->driver->putConditions([['name' => 'GST', 'type' => 'tax', 'value' => '10%']]);
+        expect($this->driver->getConditions())->toBe([['name' => 'GST', 'type' => 'tax', 'value' => '10%']]);
+    });
+
+    test('clearItems empties items but keeps conditions', function () {
+        $this->driver->putItems([['id' => 1]]);
+        $this->driver->putConditions([['name' => 'GST']]);
+        $this->driver->clearItems();
+
+        expect($this->driver->getItems())->toBe([]);
+        expect($this->driver->getConditions())->toBe([['name' => 'GST']]);
+    });
+
+    test('flush empties items and conditions', function () {
+        $this->driver->putItems([['id' => 1]]);
+        $this->driver->putConditions([['name' => 'GST']]);
+        $this->driver->flush();
+
+        expect($this->driver->getItems())->toBe([]);
+        expect($this->driver->getConditions())->toBe([]);
+    });
+
+    test('setSessionKey updates the key', function () {
+        $this->driver->setSessionKey('new-key');
+        expect($this->driver->getSessionKey())->toBe('new-key');
+    });
+
+    test('getSessionModel returns null', function () {
+        expect($this->driver->getSessionModel())->toBeNull();
+    });
+});