Solve bug #116 - Setting number of address line lower breaks checkout

app/code/Magento/Customer/Model/Address/AbstractAddress.php

@@ -17,6 +17,7 @@
 use Magento\Framework\App\ObjectManager;
 use Magento\Framework\Model\AbstractExtensibleModel;
 use Magento\Framework\ObjectManager\ResetAfterRequestInterface;
+use Magento\Customer\Helper\Address as AddressHelper;
 
 /**
  * Address abstract model
@@ -146,6 +147,11 @@ class AbstractAddress extends AbstractExtensibleModel implements AddressModelInt
      */
     private array $regionIdCountry = [];
 
+    /**
+     * @var AddressHelper|null
+     */
+    protected ?AddressHelper $addressHelper;
+
     /**
      * @param \Magento\Framework\Model\Context $context
      * @param \Magento\Framework\Registry $registry
@@ -166,6 +172,7 @@ class AbstractAddress extends AbstractExtensibleModel implements AddressModelInt
      * @param CompositeValidator $compositeValidator
      * @param CountryModelsCache|null $countryModelsCache
      * @param RegionModelsCache|null $regionModelsCache
+     * @param Magento\Customer\Helper\Address\AddressHelper|null $addressHelper
      *
      * @SuppressWarnings(PHPMD.ExcessiveParameterList)
      */
@@ -189,6 +196,7 @@ public function __construct(
         ?CompositeValidator $compositeValidator = null,
         ?CountryModelsCache $countryModelsCache = null,
         ?RegionModelsCache $regionModelsCache = null,
+        ?AddressHelper $addressHelper = null
     ) {
         $this->_directoryData = $directoryData;
         $data = $this->_implodeArrayField($data);
@@ -206,6 +214,8 @@ public function __construct(
             ->get(CountryModelsCache::class);
         $this->regionModelsCache = $regionModelsCache ?: ObjectManager::getInstance()
             ->get(RegionModelsCache::class);
+        $this->addressHelper = $addressHelper ?: ObjectManager::getInstance()
+            ->get(AddressHelper::class);
         parent::__construct(
             $context,
             $registry,
@@ -242,6 +252,8 @@ public function getName()
 
     /**
      * Retrieve street field of an address
+     * Honour current configured street lines, and convert
+     * legacy data to match
      *
      * @return string[]
      */
@@ -250,7 +262,11 @@ public function getStreet()
         if (is_array($this->getStreetFull())) {
             return $this->getStreetFull();
         }
-        return explode("\n", $this->getStreetFull());
+        $maxAllowedLineCount = $this->addressHelper->getStreetLines() ?? 2;
+        $lines = explode("\n", $this->getStreetFull());
+        $lines = $this->addressHelper->convertStreetLines($lines, $maxAllowedLineCount);
+        $this->setStreetFull(implode("\n", $lines));
+        return $lines;
     }
 
     /**

app/code/Magento/Customer/Test/Unit/Model/Address/AbstractAddressTest.php

@@ -70,6 +70,8 @@ class AbstractAddressTest extends TestCase
     /** @var CompositeValidator|MockObject  */
     private $compositeValidatorMock;
 
+    private $addressHelperMock;
+
     protected function setUp(): void
     {
         $this->contextMock = $this->createMock(Context::class);
@@ -491,6 +493,89 @@ function ($data) {
         );
     }
 
+    public function testGetStreetWithTwoLines()
+    {
+        // Create a partial mock for AddressHelper
+        $this->addressHelperMock = $this->getMockBuilder(\Magento\Customer\Helper\Address::class)
+            ->disableOriginalConstructor()
+            ->onlyMethods(['getStreetLines']) // Mock only getStreetLines, keep the real convertStreetLines
+            ->getMock();
+
+        // Mock getStreetLines to return 2 by default
+        $this->addressHelperMock->method('getStreetLines')->willReturn(2);
+
+        // Use reflection to inject the partial mock into the model
+        $reflection = new \ReflectionClass($this->model);
+        $property = $reflection->getProperty('addressHelper');
+        $property->setAccessible(true);
+        $property->setValue($this->model, $this->addressHelperMock);
+
+        $this->addressHelperMock->method('getStreetLines')->willReturn(2);
+        $streetData = ["Street Line 1", "Street Line 2", "Street Line 3", "Street Line 4"];
+        $this->model->setData('street', $streetData);
+
+        // Call getStreet() which should internally call convertStreetLines()
+        $result = $this->model->getStreet();
+
+        // Assert that empty and whitespace-only lines are removed by convertStreetLines
+        $this->assertEquals(["Street Line 1 Street Line 2", "Street Line 3 Street Line 4"], $result);
+    }
+
+    public function testGetStreetWithThreeLines()
+    {
+        // Create a partial mock for AddressHelper
+        $this->addressHelperMock = $this->getMockBuilder(\Magento\Customer\Helper\Address::class)
+            ->disableOriginalConstructor()
+            ->onlyMethods(['getStreetLines']) // Mock only getStreetLines, keep the real convertStreetLines
+            ->getMock();
+
+        // Mock getStreetLines to return 2 by default
+        $this->addressHelperMock->method('getStreetLines')->willReturn(3);
+
+        // Use reflection to inject the partial mock into the model
+        $reflection = new \ReflectionClass($this->model);
+        $property = $reflection->getProperty('addressHelper');
+        $property->setAccessible(true);
+        $property->setValue($this->model, $this->addressHelperMock);
+
+        $this->addressHelperMock->method('getStreetLines')->willReturn(3);
+        $streetData = ["Street Line 1", "Street Line 2", "Street Line 3", "Street Line 4"];
+        $this->model->setData('street', $streetData);
+
+        // Call getStreet() which should internally call convertStreetLines()
+        $result = $this->model->getStreet();
+
+        // Assert that empty and whitespace-only lines are removed by convertStreetLines
+        $this->assertEquals(["Street Line 1 Street Line 2","Street Line 3","Street Line 4"], $result);
+    }
+
+    public function testGetStreetWithOneLine()
+    {
+        // Create a partial mock for AddressHelper
+        $this->addressHelperMock = $this->getMockBuilder(\Magento\Customer\Helper\Address::class)
+            ->disableOriginalConstructor()
+            ->onlyMethods(['getStreetLines']) // Mock only getStreetLines, keep the real convertStreetLines
+            ->getMock();
+
+        // Mock getStreetLines to return 2 by default
+        $this->addressHelperMock->method('getStreetLines')->willReturn(1);
+
+        // Use reflection to inject the partial mock into the model
+        $reflection = new \ReflectionClass($this->model);
+        $property = $reflection->getProperty('addressHelper');
+        $property->setAccessible(true);
+        $property->setValue($this->model, $this->addressHelperMock);
+
+        $streetData = ["Street Line 1", "Street Line 2", "Street Line 3", "Street Line 4"];
+        $this->model->setData('street', $streetData);
+
+        // Call getStreet() which should internally call convertStreetLines()
+        $result = $this->model->getStreet();
+
+        // Assert that empty and whitespace-only lines are removed by convertStreetLines
+        $this->assertEquals(["Street Line 1 Street Line 2 Street Line 3 Street Line 4"], $result);
+    }
+
     protected function tearDown(): void
     {
         $this->objectManager->setBackwardCompatibleProperty(

app/code/Magento/Customer/etc/di.xml

@@ -593,4 +593,9 @@
                 type="Magento\Customer\Plugin\AsyncRequestCustomerGroupAuthorization"
         />
     </type>
+    <type name="Magento\Customer\Model\Address\AbstractAddress">
+        <arguments>
+            <argument name="addressHelper" xsi:type="object">Magento\Customer\Helper\Address</argument>
+        </arguments>
+    </type>
 </config>