Added test coverage for DatabaseOperations.sql_flush().

tests/backends/mysql/test_operations.py

@@ -0,0 +1,62 @@
+import unittest
+
+from django.core.management.color import no_style
+from django.db import connection
+from django.test import SimpleTestCase
+
+from ..models import Person, Square, Tag
+
+
+@unittest.skipUnless(connection.vendor == 'mysql', 'MySQL tests.')
+class MySQLOperationsTests(SimpleTestCase):
+    def test_sql_flush(self):
+        # allow_cascade doesn't change statements on MySQL.
+        for allow_cascade in [False, True]:
+            with self.subTest(allow_cascade=allow_cascade):
+                statements = connection.ops.sql_flush(
+                    no_style(),
+                    [Person._meta.db_table, Tag._meta.db_table],
+                    [],
+                    allow_cascade=allow_cascade,
+                )
+                self.assertEqual(statements[0], 'SET FOREIGN_KEY_CHECKS = 0;')
+                # The tables are processed in an unordered set.
+                self.assertEqual(
+                    sorted(statements[1:-1]),
+                    [
+                        'DELETE FROM `backends_person`;',
+                        'DELETE FROM `backends_tag`;',
+                    ],
+                )
+                self.assertEqual(statements[-1], 'SET FOREIGN_KEY_CHECKS = 1;')
+
+    def test_sql_flush_sequences(self):
+        # allow_cascade doesn't change statements on MySQL.
+        for allow_cascade in [False, True]:
+            with self.subTest(allow_cascade=allow_cascade):
+                statements = connection.ops.sql_flush(
+                    no_style(),
+                    [Person._meta.db_table, Square._meta.db_table, Tag._meta.db_table],
+                    [
+                        {
+                            'table': Person._meta.db_table,
+                            'column': Person._meta.pk.db_column,
+                        },
+                        {
+                            'table': Tag._meta.db_table,
+                            'column': Tag._meta.pk.db_column,
+                        },
+                    ],
+                    allow_cascade=allow_cascade,
+                )
+                self.assertEqual(statements[0], 'SET FOREIGN_KEY_CHECKS = 0;')
+                # The tables are processed in an unordered set.
+                self.assertEqual(
+                    sorted(statements[1:-1]),
+                    [
+                        'DELETE FROM `backends_square`;',
+                        'TRUNCATE `backends_person`;',
+                        'TRUNCATE `backends_tag`;',
+                    ],
+                )
+                self.assertEqual(statements[-1], 'SET FOREIGN_KEY_CHECKS = 1;')