MDL-40883 ddl: unittest for objects name length

lib/ddl/tests/ddl_test.php

@@ -1879,6 +1879,59 @@ public function test_char_size_limit() {
         }
     }
 
+    public function test_object_name() {
+        $gen = $this->tdb->get_manager()->generator;
+
+        // This will form short object name and max length should not be exceeded.
+        $table = 'tablename';
+        $fields = 'id';
+        $suffix = 'pk';
+        for ($i=0; $i<12; $i++) {
+            $this->assertLessThanOrEqual($gen->names_max_length,
+                    strlen($gen->getNameForObject($table, $fields, $suffix)),
+                    'Generated object name is too long. $i = '.$i);
+        }
+
+        // This will form too long object name always and it must be trimmed to exactly 30 chars.
+        $table = 'aaaa_bbbb_cccc_dddd_eeee_ffff_gggg';
+        $fields = 'aaaaa,bbbbb,ccccc,ddddd';
+        $suffix = 'idx';
+        for ($i=0; $i<12; $i++) {
+            $this->assertEquals($gen->names_max_length,
+                    strlen($gen->getNameForObject($table, $fields, $suffix)),
+                    'Generated object name is too long. $i = '.$i);
+        }
+
+        // Same test without suffix.
+        $table = 'bbbb_cccc_dddd_eeee_ffff_gggg_hhhh';
+        $fields = 'aaaaa,bbbbb,ccccc,ddddd';
+        $suffix = '';
+        for ($i=0; $i<12; $i++) {
+            $this->assertEquals($gen->names_max_length,
+                    strlen($gen->getNameForObject($table, $fields, $suffix)),
+                    'Generated object name is too long. $i = '.$i);
+        }
+
+        // This must only trim name when counter is 10 or more.
+        $table = 'cccc_dddd_eeee_ffff_gggg_hhhh_iiii';
+        $fields = 'id';
+        $suffix = 'idx';
+        // Since we don't know how long prefix is, loop to generate tablename that gives exactly maxlengh-1 length.
+        // Skip this test if prefix is too long.
+        while (strlen($table) && strlen($gen->prefix.preg_replace('/_/','',$table).'_id_'.$suffix) >= $gen->names_max_length) {
+            $table = rtrim(substr($table, 0, strlen($table) - 1), '_');
+        }
+        if (strlen($table)) {
+            $this->assertEquals($gen->names_max_length - 1,
+                        strlen($gen->getNameForObject($table, $fields, $suffix)));
+            for ($i=0; $i<12; $i++) {
+                $this->assertEquals($gen->names_max_length,
+                        strlen($gen->getNameForObject($table, $fields, $suffix)),
+                        'Generated object name is too long. $i = '.$i);
+            }
+        }
+    }
+
     // Following methods are not supported == Do not test.
     /*
         public function testRenameIndex() {