Add check for duplicate migrations names when loading migrations

[MAILPOET-5416]

mailpoet/lib/Migrator/MigratorException.php

@@ -18,6 +18,12 @@ class MigratorException extends InvalidStateException {
     );
   }
 
+  public static function duplicateMigrationNames(array $names): self {
+    return self::create()->withMessage(
+      sprintf('Duplicate migration names are not allowed. Duplicate names found: "%s".', join(', ', $names))
+    );
+  }
+
   public static function migrationFileWriteFailed(string $path): self {
     return self::create()->withMessage(
       sprintf('Could not write migration file "%s".', $path)

mailpoet/lib/Migrator/Repository.php

@@ -55,10 +55,15 @@ class Repository {
    * @return array<array{level: string, name: string}>
    */
   public function loadAll(): array {
-    return array_merge(
+    $migrations = array_merge(
       $this->loadForLevel(self::MIGRATIONS_LEVEL_DB),
       $this->loadForLevel(self::MIGRATIONS_LEVEL_APP)
     );
+    $duplicateNames = array_diff_assoc(array_column($migrations, 'name'), array_unique(array_column($migrations, 'name')));
+    if (!empty($duplicateNames)) {
+      throw MigratorException::duplicateMigrationNames($duplicateNames);
+    }
+    return $migrations;
   }
 
   private function loadForLevel(string $level): array {

mailpoet/tests/unit/Migrator/RepositoryTest.php

@@ -59,6 +59,18 @@ class RepositoryTest extends MailPoetUnitTest {
     $repository->create('abc');
   }
 
+  public function testItFailsWhenThereAreMigrationsWithDuplicateNames(): void {
+    $migrationsDir = __DIR__ . '/TestMigrationsDuplicates';
+    $repository = $this->make(Repository::class, [
+      'migrationsDir' => $migrationsDir,
+      'templateFile' => self::TEMPLATE_FILE,
+    ]);
+
+    $this->expectException(MigratorException::class);
+    $this->expectExceptionMessage('Duplicate migration names are not allowed. Duplicate names found: "MigrationDuplicate".');
+    $repository->loadAll();
+  }
+
   public function testItLoadsMigrationFiles(): void {
     $repository = $this->make(Repository::class, [
       'migrationsDir' => __DIR__ . '/TestMigrations',

mailpoet/tests/unit/Migrator/TestMigrationsDuplicates/App/MigrationDuplicate.php

@@ -0,0 +1,11 @@
+<?php declare(strict_types = 1);
+
+namespace MailPoet\Migrations\App;
+
+use MailPoet\Migrator\AppMigration;
+
+//phpcs:disable Squiz.Classes.ValidClassName.NotCamelCaps
+class MigrationDuplicate extends AppMigration {
+  public function run(): void {
+  }
+}

mailpoet/tests/unit/Migrator/TestMigrationsDuplicates/Db/MigrationDuplicate.php

@@ -0,0 +1,11 @@
+<?php declare(strict_types = 1);
+
+namespace MailPoet\Migrations\Db;
+
+use MailPoet\Migrator\DbMigration;
+
+//phpcs:disable Squiz.Classes.ValidClassName.NotCamelCaps
+class MigrationDuplicate extends DbMigration {
+  public function run(): void {
+  }
+}