From 66c34d357874d62a2e3d0a180e91ba80b45e0372 Mon Sep 17 00:00:00 2001
From: Matteo Scaramuccia <moodle@matteoscaramuccia.com>
Date: Thu, 13 Sep 2018 21:55:17 +0200
Subject: [PATCH] MDL-63319 ddl: Improved rename_field() coverage

DB API should allow to rename fields, including renaming
those columns named using a reserved word.
---
 lib/ddl/tests/ddl_test.php | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/lib/ddl/tests/ddl_test.php b/lib/ddl/tests/ddl_test.php
index 2f42a6276e113..d79d4304346be 100644
--- a/lib/ddl/tests/ddl_test.php
+++ b/lib/ddl/tests/ddl_test.php
@@ -1545,12 +1545,45 @@ public function testRenameField() {
         $field = new xmldb_field('type');
         $field->set_attributes(XMLDB_TYPE_CHAR, '20', null, XMLDB_NOTNULL, null, 'general', 'course');
 
+        // 1. Rename the 'type' field into a generic new valid name.
+        // This represents the standard use case.
         $dbman->rename_field($table, $field, 'newfieldname');
 
         $columns = $DB->get_columns('test_table0');
 
         $this->assertArrayNotHasKey('type', $columns);
         $this->assertArrayHasKey('newfieldname', $columns);
+        $field->setName('newfieldname');
+
+        // 2. Rename the 'newfieldname' field into a reserved word, for testing purposes.
+        // This represents a questionable use case: we should support it but discourage the use of it on peer reviewing.
+        $dbman->rename_field($table, $field, 'where');
+
+        $columns = $DB->get_columns('test_table0');
+
+        $this->assertArrayNotHasKey('newfieldname', $columns);
+        $this->assertArrayHasKey('where', $columns);
+
+        // 3. Create a table with a column name named w/ a reserved word and get rid of it.
+        // This represents a "recovering" use case: a field name could be a reserved word in the future, at least for a DB type.
+        $table = new xmldb_table('test_table_res_word');
+        $table->add_field('id', XMLDB_TYPE_INTEGER, '10', null, XMLDB_NOTNULL, XMLDB_SEQUENCE, null);
+        $table->add_field('where', XMLDB_TYPE_INTEGER, '10', null, XMLDB_NOTNULL, null, '0');
+        $table->add_key('primary', XMLDB_KEY_PRIMARY, array('id'));
+        $table->setComment("This is a test'n drop table. You can drop it safely");
+        $dbman->create_table($table);
+        $dbman->table_exists('test_table_res_word');
+
+        $columns = $DB->get_columns('test_table_res_word');
+        $this->assertArrayHasKey('where', $columns);
+        $field = $table->getField('where');
+
+        $dbman->rename_field($table, $field, 'newfieldname');
+
+        $columns = $DB->get_columns('test_table_res_word');
+
+        $this->assertArrayNotHasKey('where', $columns);
+        $this->assertArrayHasKey('newfieldname', $columns);
     }
 
     public function testIndexExists() {