diff --git a/freqtrade/strategy/strategyupdater.py b/freqtrade/strategy/strategyupdater.py
index 6fe1f326c..bc692b71c 100644
--- a/freqtrade/strategy/strategyupdater.py
+++ b/freqtrade/strategy/strategyupdater.py
@@ -3,6 +3,8 @@ from pathlib import Path
 
 import ast_comments
 
+from freqtrade.constants import Config
+
 
 class StrategyUpdater:
     name_mapping = {
@@ -42,7 +44,7 @@ class StrategyUpdater:
     # create a dictionary that maps the old column names to the new ones
     rename_dict = {'buy': 'enter_long', 'sell': 'exit_long', 'buy_tag': 'enter_tag'}
 
-    def start(self, config, strategy_obj: dict) -> None:
+    def start(self, config: Config, strategy_obj: dict) -> None:
         """
         Run strategy updater
         It updates a strategy to v3 with the help of the ast-module
diff --git a/tests/commands/test_commands.py b/tests/commands/test_commands.py
index 179712c6d..318590b32 100644
--- a/tests/commands/test_commands.py
+++ b/tests/commands/test_commands.py
@@ -1549,7 +1549,7 @@ def test_start_convert_db(mocker, fee, tmpdir, caplog):
     assert db_target_file.is_file()
 
 
-def test_start_strategy_updater(mocker,  tmpdir):
+def test_start_strategy_updater(mocker, tmpdir):
     sc_mock = mocker.patch('freqtrade.commands.strategy_utils_commands.start_conversion')
     teststrats = Path(__file__).parent.parent / 'strategy/strats'
     args = [
diff --git a/tests/test_strategy_updater.py b/tests/test_strategy_updater.py
index 4aad152bf..d3bdd27b5 100644
--- a/tests/test_strategy_updater.py
+++ b/tests/test_strategy_updater.py
@@ -1,16 +1,56 @@
 # pragma pylint: disable=missing-docstring, protected-access, invalid-name
 
+import re
+import shutil
 import sys
+from pathlib import Path
 
 import pytest
 
+from freqtrade.commands.strategy_utils_commands import start_strategy_update
 from freqtrade.strategy.strategyupdater import StrategyUpdater
+from tests.conftest import get_args
 
 
 if sys.version_info < (3, 9):
     pytest.skip("StrategyUpdater is not compatible with Python 3.8", allow_module_level=True)
 
 
+def test_strategy_updater_start(tmpdir, capsys) -> None:
+    # Effective test without mocks.
+    teststrats = Path(__file__).parent / 'strategy/strats'
+    tmpdirp = Path(tmpdir) / "strategies"
+    tmpdirp.mkdir()
+    shutil.copy(teststrats / 'strategy_test_v2.py', tmpdirp)
+    old_code = (teststrats / 'strategy_test_v2.py').read_text()
+
+    args = [
+        "strategy-updater",
+        "--userdir",
+        str(tmpdir),
+        "--strategy-list",
+        "StrategyTestV2"
+         ]
+    pargs = get_args(args)
+    pargs['config'] = None
+
+    start_strategy_update(pargs)
+
+    assert Path(tmpdir / "strategies_orig_updater").exists()
+    # Backup file exists
+    assert Path(tmpdir / "strategies_orig_updater" / 'strategy_test_v2.py').exists()
+    # updated file exists
+    new_file = Path(tmpdirp / 'strategy_test_v2.py')
+    assert new_file.exists()
+    new_code = new_file.read_text()
+    assert 'INTERFACE_VERSION = 3' in new_code
+    assert 'INTERFACE_VERSION = 2' in old_code
+    captured = capsys.readouterr()
+
+    assert 'Conversion of strategy_test_v2.py started.' in captured.out
+    assert re.search(r'Conversion of strategy_test_v2\.py took .* seconds', captured.out)
+
+
 def test_strategy_updater_methods(default_conf, caplog) -> None:
 
     instance_strategy_updater = StrategyUpdater()
@@ -155,6 +195,7 @@ import freqtrade.vendor.qtpylib.indicators as qtpylib
 
 
 class someStrategy(IStrategy):
+    INTERFACE_VERSION = 2
     # This is the 3rd comment
     # This attribute will be overridden if the config file contains "minimal_roi"
     minimal_roi = {
@@ -168,5 +209,6 @@ class someStrategy(IStrategy):
     assert "This is the 1st comment" in modified_code
     assert "This is the 2nd comment" in modified_code
     assert "This is the 3rd comment" in modified_code
+    assert "INTERFACE_VERSION = 3" in modified_code
     # currently still missing:
     # Webhook terminology, Telegram notification settings, Strategy/Config settings