Add feature flags to disable some breaking changes

docs/en/configuration.rst

@@ -512,3 +512,17 @@ Within the bootstrap script, the following variables will be available:
      * @var \Symfony\Component\Console\Output\OutputInterface $output The executing command's output object
      * @var \Phinx\Console\Command\AbstractCommand $context the executing command object
      */
+
+Feature Flags
+-------------
+
+For some breaking changes, Phinx offers a way to opt-out of new behavior. The following flags are available:
+
+* ``unsigned_pks``: Should Phinx create primary keys as unsigned integers? (default: ``true``)
+* ``column_null``: Should Phinx create columns as null by default? (default: ``true``)
+
+These values can also be set by modifying class fields on the ```Phinx\Config\FeatureFlags``` class, for example:
+
+.. code-block:: php
+
+    Phinx\Config\FeatureFlags::$unsignedPks = false;

src/Phinx/Config/Config.php

@@ -57,6 +57,10 @@ public function __construct(array $configArray, ?string $configFilePath = null)
     {
         $this->configFilePath = $configFilePath;
         $this->values = $this->replaceTokens($configArray);
+
+        if (isset($this->values['feature_flags'])) {
+            FeatureFlags::setFlagsFromConfig($this->values['feature_flags']);
+        }
     }
 
     /**

src/Phinx/Config/FeatureFlags.php

@@ -0,0 +1,41 @@
+<?php
+
+/**
+ * MIT License
+ * For full license information, please view the LICENSE file that was distributed with this source code.
+ */
+
+namespace Phinx\Config;
+
+/**
+ * Class to hold features flags to toggle breaking changes in Phinx.
+ *
+ * New flags should be added very sparingly.
+ */
+class FeatureFlags
+{
+    /**
+     * @var bool Should Phinx create unsigned primary keys by default?
+     */
+    public static $unsignedPks = true;
+    /**
+     * @var bool Should Phinx create columns NULL by default?
+     */
+    public static $columnNull = true;
+
+    /**
+     * Set the feature flags from the `feature_flags` section of the overall
+     * config.
+     *
+     * @param array $config The `feature_flags` section of the config
+     */
+    public static function setFlagsFromConfig(array $config): void
+    {
+        if (isset($config['unsigned_pks'])) {
+            self::$unsignedPks = (bool)$config['unsigned_pks'];
+        }
+        if (isset($config['column_null'])) {
+            self::$columnNull = (bool)$config['column_null'];
+        }
+    }
+}

src/Phinx/Db/Adapter/MysqlAdapter.php

@@ -11,6 +11,7 @@
 use Cake\Database\Driver\Mysql as MysqlDriver;
 use InvalidArgumentException;
 use PDO;
+use Phinx\Config\FeatureFlags;
 use Phinx\Db\Table\Column;
 use Phinx\Db\Table\ForeignKey;
 use Phinx\Db\Table\Index;
@@ -285,7 +286,7 @@ public function createTable(Table $table, array $columns = [], array $indexes =
             $column->setName($options['id'])
                    ->setType('integer')
                    ->setOptions([
-                       'signed' => $options['signed'] ?? false,
+                       'signed' => $options['signed'] ?? !FeatureFlags::$unsignedPks,
                        'identity' => true,
                    ]);
 

src/Phinx/Db/Table/Column.php

@@ -7,6 +7,7 @@
 
 namespace Phinx\Db\Table;
 
+use Phinx\Config\FeatureFlags;
 use Phinx\Db\Adapter\AdapterInterface;
 use Phinx\Db\Adapter\PostgresAdapter;
 use RuntimeException;
@@ -158,6 +159,14 @@ class Column
      */
     protected $values;
 
+    /**
+     * Column constructor
+     */
+    public function __construct()
+    {
+        $this->null = FeatureFlags::$columnNull;
+    }
+
     /**
      * Sets the column name.
      *

tests/Phinx/Config/FeatureFlagsTest.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace Test\Phinx\Config;
+
+use Phinx\Config\FeatureFlags;
+use PHPUnit\Framework\TestCase;
+
+class FeatureFlagsTest extends TestCase
+{
+    /**
+     * @runInSeparateProcess
+     */
+    public function testSetFlagsFromConfig(): void
+    {
+        $config = [
+            'unsigned_pks' => false,
+            'column_null' => false,
+        ];
+        $this->assertTrue(FeatureFlags::$unsignedPks);
+        $this->assertTrue(FeatureFlags::$columnNull);
+        FeatureFlags::setFlagsFromConfig($config);
+        $this->assertFalse(FeatureFlags::$unsignedPks);
+        $this->assertFalse(FeatureFlags::$columnNull);
+    }
+}

tests/Phinx/Db/Adapter/MysqlAdapterTest.php

@@ -4,6 +4,7 @@
 namespace Test\Phinx\Db\Adapter;
 
 use PDOException;
+use Phinx\Config\FeatureFlags;
 use Phinx\Db\Adapter\AdapterInterface;
 use Phinx\Db\Adapter\MysqlAdapter;
 use Phinx\Util\Literal;
@@ -156,6 +157,11 @@ public function testCreateTable()
         $this->assertTrue($this->adapter->hasColumn('ntable', 'realname'));
         $this->assertTrue($this->adapter->hasColumn('ntable', 'email'));
         $this->assertFalse($this->adapter->hasColumn('ntable', 'address'));
+
+        $columns = $this->adapter->getColumns('ntable');
+        $this->assertCount(3, $columns);
+        $this->assertSame('id', $columns[0]->getName());
+        $this->assertFalse($columns[0]->isSigned());
     }
 
     public function testCreateTableWithComment()
@@ -421,6 +427,25 @@ public function testCreateTableWithLatin1Collate()
         $this->assertEquals('latin1_general_ci', $row['Collation']);
     }
 
+    public function testCreateTableWithSignedPK()
+    {
+        $table = new \Phinx\Db\Table('ntable', ['signed' => true], $this->adapter);
+        $table->addColumn('realname', 'string')
+            ->addColumn('email', 'integer')
+            ->save();
+        $this->assertTrue($this->adapter->hasTable('ntable'));
+        $this->assertTrue($this->adapter->hasColumn('ntable', 'id'));
+        $this->assertTrue($this->adapter->hasColumn('ntable', 'realname'));
+        $this->assertTrue($this->adapter->hasColumn('ntable', 'email'));
+        $this->assertFalse($this->adapter->hasColumn('ntable', 'address'));
+        $column_definitions = $this->adapter->getColumns('ntable');
+        foreach ($column_definitions as $column_definition) {
+            if ($column_definition->getName() === 'id') {
+                $this->assertTrue($column_definition->getSigned());
+            }
+        }
+    }
+
     public function testCreateTableWithUnsignedPK()
     {
         $table = new \Phinx\Db\Table('ntable', ['signed' => false], $this->adapter);
@@ -459,6 +484,24 @@ public function testCreateTableWithUnsignedNamedPK()
         $this->assertFalse($this->adapter->hasColumn('ntable', 'address'));
     }
 
+    /**
+     * @runInSeparateProcess
+     */
+    public function testUnsignedPksFeatureFlag()
+    {
+        $this->adapter->connect();
+
+        FeatureFlags::$unsignedPks = false;
+
+        $table = new \Phinx\Db\Table('table1', [], $this->adapter);
+        $table->create();
+
+        $columns = $this->adapter->getColumns('table1');
+        $this->assertCount(1, $columns);
+        $this->assertSame('id', $columns[0]->getName());
+        $this->assertTrue($columns[0]->getSigned());
+    }
+
     public function testCreateTableWithLimitPK()
     {
         $table = new \Phinx\Db\Table('ntable', ['id' => 'id', 'limit' => 4], $this->adapter);

tests/Phinx/Db/Table/ColumnTest.php

@@ -2,6 +2,7 @@
 
 namespace Test\Phinx\Db\Table;
 
+use Phinx\Config\FeatureFlags;
 use Phinx\Db\Table\Column;
 use PHPUnit\Framework\TestCase;
 use RuntimeException;
@@ -28,4 +29,17 @@ public function testSetOptionsIdentity()
         $this->assertFalse($column->isNull());
         $this->assertTrue($column->isIdentity());
     }
+
+    /**
+     * @runInSeparateProcess
+     */
+    public function testColumnNullFeatureFlag()
+    {
+        $column = new Column();
+        $this->assertTrue($column->isNull());
+
+        FeatureFlags::$columnNull = false;
+        $column = new Column();
+        $this->assertFalse($column->isNull());
+    }
 }