From 79925d2c2979a233cc43998a5a3be1f7156edc61 Mon Sep 17 00:00:00 2001
From: Alex Pott <alex.a.pott@googlemail.com>
Date: Tue, 19 Apr 2022 09:14:22 +0100
Subject: [PATCH] Issue #3269091 by gambry, yogeshmpawar, jonathanshaw,
 joachim, alexpott: Undocumented behaviour for Schema::findTables() when an
 underscore is used

---
 core/lib/Drupal/Core/Database/Schema.php      |  7 ++-
 .../KernelTests/Core/Database/SchemaTest.php  | 55 +++++++++++++++++++
 2 files changed, 61 insertions(+), 1 deletion(-)

diff --git a/core/lib/Drupal/Core/Database/Schema.php b/core/lib/Drupal/Core/Database/Schema.php
index ed3a04eecb7..9f14f359214 100644
--- a/core/lib/Drupal/Core/Database/Schema.php
+++ b/core/lib/Drupal/Core/Database/Schema.php
@@ -180,7 +180,12 @@ abstract class Schema implements PlaceholderInterface {
    * Finds all tables that are like the specified base table name.
    *
    * @param string $table_expression
-   *   An SQL expression, for example "cache_%" (without the quotes).
+   *   A case-insensitive pattern against which table names are compared. Both
+   *   '_' and '%' are treated like wildcards in MySQL 'LIKE' expressions, where
+   *   '_' matches any single character and '%' matches an arbitrary number of
+   *   characters (including zero characters). So 'foo%bar' matches table names
+   *   like 'foobar', 'fooXBar', 'fooXBaR',  or 'fooXxBar'; whereas 'foo_bar'
+   *   matches 'fooXBar' and 'fooXBaR' but not 'fooBar' or 'fooXxxBar'.
    *
    * @return array
    *   Both the keys and the values are the matching tables.
diff --git a/core/tests/Drupal/KernelTests/Core/Database/SchemaTest.php b/core/tests/Drupal/KernelTests/Core/Database/SchemaTest.php
index b0ffb5d58f7..a1ccad0efe1 100644
--- a/core/tests/Drupal/KernelTests/Core/Database/SchemaTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Database/SchemaTest.php
@@ -1307,6 +1307,61 @@ class SchemaTest extends KernelTestBase {
       'test_2_table',
     ];
     $this->assertEquals($expected, $tables, 'Two tables were found.');
+
+    // Check '_' and '%' wildcards.
+    $test_schema->createTable('test3table', $table_specification);
+    $test_schema->createTable('test4', $table_specification);
+    $test_schema->createTable('testTable', $table_specification);
+    $test_schema->createTable('test', $table_specification);
+
+    $tables = $test_schema->findTables('test%');
+    sort($tables);
+    $expected = [
+      'test',
+      'test3table',
+      'test4',
+      'testTable',
+      'test_1_table',
+      'test_2_table',
+    ];
+    $this->assertEquals($expected, $tables, 'All "test" prefixed tables were found.');
+
+    $tables = $test_schema->findTables('test_%');
+    sort($tables);
+    $expected = [
+      'test3table',
+      'test4',
+      'testTable',
+      'test_1_table',
+      'test_2_table',
+    ];
+    $this->assertEquals($expected, $tables, 'All "/^test..*?/" tables were found.');
+
+    $tables = $test_schema->findTables('test%table');
+    sort($tables);
+    $expected = [
+      'test3table',
+      'testTable',
+      'test_1_table',
+      'test_2_table',
+    ];
+    $this->assertEquals($expected, $tables, 'All "/^test.*?table/" tables were found.');
+
+    $tables = $test_schema->findTables('test_%table');
+    sort($tables);
+    $expected = [
+      'test3table',
+      'test_1_table',
+      'test_2_table',
+    ];
+    $this->assertEquals($expected, $tables, 'All "/^test..*?table/" tables were found.');
+
+    $tables = $test_schema->findTables('test_');
+    sort($tables);
+    $expected = [
+      'test4',
+    ];
+    $this->assertEquals($expected, $tables, 'All "/^test./" tables were found.');
   }
 
   /**