test: fix tests that depends on table state

Author: kenjis

tests/_support/MigrationTestMigrations/Database/Migrations/2018-01-24-102301_Some_migration.php

@@ -21,7 +21,7 @@ public function up()
                 'constraint' => 255,
             ],
         ]);
-        $this->forge->createTable('foo', true);
+        $this->forge->createTable('foo');
 
         $this->db->table('foo')->insert([
             'key' => 'foobar',

tests/system/Database/Migrations/MigrationRunnerTest.php

@@ -349,6 +349,9 @@ public function testLatestSuccess()
 
     public function testRegressSuccess()
     {
+        $forge = Database::forge();
+        $forge->dropTable('foo', true);
+
         $runner = new MigrationRunner($this->config);
         $runner->setSilent(false)
             ->setNamespace('Tests\Support\MigrationTestMigrations')
@@ -368,6 +371,9 @@ public function testRegressSuccess()
 
     public function testLatestTriggersEvent()
     {
+        $forge = Database::forge();
+        $forge->dropTable('foo', true);
+
         $runner = new MigrationRunner($this->config);
         $runner->setSilent(false)
             ->setNamespace('Tests\Support\MigrationTestMigrations');
@@ -387,6 +393,9 @@ public function testLatestTriggersEvent()
 
     public function testRegressTriggersEvent()
     {
+        $forge = Database::forge();
+        $forge->dropTable('foo', true);
+
         $runner = new MigrationRunner($this->config);
         $runner->setSilent(false)
             ->setNamespace('Tests\Support\MigrationTestMigrations');