From e9c25e31e26537c32c399d9cc848a6b5ff82a739 Mon Sep 17 00:00:00 2001
From: Wilmer Arambula <42547589+terabytesoftw@users.noreply.github.com>
Date: Wed, 5 Apr 2023 03:30:42 -0400
Subject: [PATCH] Add command `showDatabases()`. (#275)

---
 src/CommandPDO.php          |  9 +++++++++
 src/Dsn.php                 |  2 +-
 tests/CommandTest.php       | 15 +++++++++++++++
 tests/DsnTest.php           | 15 +++++++++++++++
 tests/Support/TestTrait.php | 10 ++--------
 5 files changed, 42 insertions(+), 9 deletions(-)

diff --git a/src/CommandPDO.php b/src/CommandPDO.php
index ab9485530..64e3d84db 100644
--- a/src/CommandPDO.php
+++ b/src/CommandPDO.php
@@ -44,6 +44,15 @@ public function insertWithReturningPks(string $table, array $columns): bool|arra
         return $result;
     }
 
+    public function showDatabases(): array
+    {
+        $sql = <<<SQL
+        SHOW DATABASES WHERE `Database` NOT IN ('information_schema', 'mysql', 'performance_schema', 'sys')
+        SQL;
+
+        return $this->setSql($sql)->queryColumn();
+    }
+
     protected function getQueryBuilder(): QueryBuilderInterface
     {
         return $this->db->getQueryBuilder();
diff --git a/src/Dsn.php b/src/Dsn.php
index 4c46a0506..77b92b021 100644
--- a/src/Dsn.php
+++ b/src/Dsn.php
@@ -19,7 +19,7 @@ final class Dsn extends AbstractDsn
     public function __construct(
         string $driver,
         string $host,
-        string $databaseName,
+        string|null $databaseName = null,
         string $port = '3306',
         array $options = []
     ) {
diff --git a/tests/CommandTest.php b/tests/CommandTest.php
index 0731c937f..fb3ee0fc6 100644
--- a/tests/CommandTest.php
+++ b/tests/CommandTest.php
@@ -8,8 +8,12 @@
 use Yiisoft\Db\Exception\Exception;
 use Yiisoft\Db\Exception\InvalidConfigException;
 use Yiisoft\Db\Exception\NotSupportedException;
+use Yiisoft\Db\Mysql\ConnectionPDO;
+use Yiisoft\Db\Mysql\Dsn;
+use Yiisoft\Db\Mysql\PDODriver;
 use Yiisoft\Db\Mysql\Tests\Support\TestTrait;
 use Yiisoft\Db\Tests\Common\CommonCommandTest;
+use Yiisoft\Db\Tests\Support\DbHelper;
 
 /**
  * @group mysql
@@ -133,4 +137,15 @@ public function testUpsert(array $firstData, array $secondData): void
     {
         parent::testUpsert($firstData, $secondData);
     }
+
+    public function testShowDatabases(): void
+    {
+        $dsn = new Dsn('mysql', '127.0.0.1', );
+        $db = new ConnectionPDO(new PDODriver($dsn->asString(), 'root', ''), DbHelper::getSchemaCache());
+
+        $command = $db->createCommand();
+
+        $this->assertSame('mysql:host=127.0.0.1;port=3306', $db->getDriver()->getDsn());
+        $this->assertSame(['yiitest'], $command->showDatabases());
+    }
 }
diff --git a/tests/DsnTest.php b/tests/DsnTest.php
index a72390e5f..052094d87 100644
--- a/tests/DsnTest.php
+++ b/tests/DsnTest.php
@@ -22,6 +22,21 @@ public function testAsString(): void
         );
     }
 
+    public function testAsStringWithDatabaseName(): void
+    {
+        $this->assertSame('mysql:host=localhost;port=3306', (new Dsn('mysql', 'localhost'))->asString());
+    }
+
+    public function testAsStringWithDatabaseNameWithEmptyString(): void
+    {
+        $this->assertSame('mysql:host=localhost;port=3306', (new Dsn('mysql', 'localhost', ''))->asString());
+    }
+
+    public function testAsStringWithDatabaseNameWithNull(): void
+    {
+        $this->assertSame('mysql:host=localhost;port=3306', (new Dsn('mysql', 'localhost', null))->asString());
+    }
+
     public function testAsStringWithOptions(): void
     {
         $this->assertSame(
diff --git a/tests/Support/TestTrait.php b/tests/Support/TestTrait.php
index c0559f4f5..74b8ebcac 100644
--- a/tests/Support/TestTrait.php
+++ b/tests/Support/TestTrait.php
@@ -16,10 +16,7 @@ trait TestTrait
 
     protected function getConnection(bool $fixture = false): ConnectionPDOInterface
     {
-        $db = new ConnectionPDO(
-            new PDODriver($this->getDsn(), 'root', ''),
-            DbHelper::getSchemaCache(),
-        );
+        $db = new ConnectionPDO(new PDODriver($this->getDsn(), 'root', ''), DbHelper::getSchemaCache());
 
         if ($fixture) {
             DbHelper::loadFixture($db, __DIR__ . '/Fixture/mysql.sql');
@@ -32,10 +29,7 @@ protected static function getDb(): ConnectionPDOInterface
     {
         $dsn = (new Dsn('mysql', '127.0.0.1', 'yiitest', '3306', ['charset' => 'utf8mb4']))->asString();
 
-        return new ConnectionPDO(
-            new PDODriver($dsn, 'root', ''),
-            DbHelper::getSchemaCache(),
-        );
+        return new ConnectionPDO(new PDODriver($dsn, 'root', ''), DbHelper::getSchemaCache());
     }
 
     protected function getDsn(): string