simplify find_backup_name_candidate & add test

easybuild/tools/filetools.py

@@ -1163,16 +1163,15 @@ def rmtree2(path, n=3):
     else:
         _log.info("Path %s successfully removed." % path)
 
+
 def find_backup_name_candidate(src_file):
-    """Returns a non-existing file to be used as destination for rotating backups"""
+    """Returns a non-existing file to be used as destination for backup files"""
     dst_file = src_file
 
-    if os.path.exists(src_file):
-        i = 0
-        dst_file = "%s_%d" % (src_file, i)
-        while os.path.exists(dst_file):
-            i += 1
-            dst_file = "%s_%d" % (src_file, i)
+    i = 0
+    while os.path.exists(dst_file):
+        dst_file = '%s_%d' % (src_file, i)
+        i += 1
 
     return dst_file
 

test/framework/filetools.py

@@ -1355,6 +1355,28 @@ def test_move_file(self):
         self.assertEqual(ft.read_file(test_file), 'test123')
         self.assertFalse(os.path.exists(new_test_file))
 
+    def test_find_backup_name_candidate(self):
+        """Test find_backup_name_candidate"""
+        test_file = os.path.join(self.test_prefix, 'test.txt')
+        ft.write_file(test_file, 'foo')
+
+        res = ft.find_backup_name_candidate(test_file)
+        self.assertTrue(os.path.samefile(os.path.dirname(res), self.test_prefix))
+        self.assertEqual(os.path.basename(res), 'test.txt_0')
+
+        ft.write_file(os.path.join(self.test_prefix, 'test.txt_0'), '')
+        res = ft.find_backup_name_candidate(test_file)
+        self.assertTrue(os.path.samefile(os.path.dirname(res), self.test_prefix))
+        self.assertEqual(os.path.basename(res), 'test.txt_1')
+
+        # generate backup files until test.txt_122
+        for idx in range(1, 123):
+            ft.write_file(os.path.join(self.test_prefix, 'test.txt_%d' % idx), '')
+
+        res = ft.find_backup_name_candidate(test_file)
+        self.assertTrue(os.path.samefile(os.path.dirname(res), self.test_prefix))
+        self.assertEqual(os.path.basename(res), 'test.txt_123')
+
 
 def suite():
     """ returns all the testcases in this module """