Make Abstract{Migration,Seed}::getAdapter return non-null

src/Phinx/Migration/AbstractMigration.php

@@ -103,8 +103,12 @@ public function setAdapter(AdapterInterface $adapter): MigrationInterface
     /**
      * @inheritDoc
      */
-    public function getAdapter(): ?AdapterInterface
+    public function getAdapter(): AdapterInterface
     {
+        if (!isset($this->adapter)) {
+            throw new RuntimeException('Cannot access `adapter` it has not been set');
+        }
+
         return $this->adapter;
     }
 

src/Phinx/Seed/AbstractSeed.php

@@ -10,6 +10,7 @@
 
 use Phinx\Db\Adapter\AdapterInterface;
 use Phinx\Db\Table;
+use RuntimeException;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 
@@ -98,6 +99,10 @@ public function setAdapter(AdapterInterface $adapter): SeedInterface
      */
     public function getAdapter(): AdapterInterface
     {
+        if (!isset($this->adapter)) {
+            throw new RuntimeException('Cannot access `adapter` it has not been set');
+        }
+
         return $this->adapter;
     }
 

tests/Phinx/Migration/AbstractMigrationTest.php

@@ -19,7 +19,8 @@ public function testAdapterMethods()
             ->getMock();
 
         // test methods
-        $this->assertNull($migrationStub->getAdapter());
+        $this->expectException(RuntimeException::class);
+        $migrationStub->getAdapter();
         $migrationStub->setAdapter($adapterStub);
         $this->assertInstanceOf(
             'Phinx\Db\Adapter\AdapterInterface',

tests/Phinx/Seed/AbstractSeedTest.php

@@ -0,0 +1,30 @@
+<?php
+declare(strict_types=1);
+
+namespace Test\Phinx\Seed;
+
+use PHPUnit\Framework\TestCase;
+use RuntimeException;
+
+class AbstractSeedTest extends TestCase
+{
+    public function testAdapterMethods()
+    {
+        // stub migration
+        $migrationStub = $this->getMockForAbstractClass('\Phinx\Seed\AbstractSeed', ['mockenv', 20230102030405]);
+
+        // stub adapter
+        $adapterStub = $this->getMockBuilder('\Phinx\Db\Adapter\PdoAdapter')
+            ->setConstructorArgs([[]])
+            ->getMock();
+
+        // test methods
+        $this->expectException(RuntimeException::class);
+        $migrationStub->getAdapter();
+        $migrationStub->setAdapter($adapterStub);
+        $this->assertInstanceOf(
+            'Phinx\Db\Adapter\AdapterInterface',
+            $migrationStub->getAdapter()
+        );
+    }
+}