git_utils: Fix '--force' option

Author: rwalton-arm

src/mbed_tools/project/_internal/git_utils.py

@@ -55,7 +55,8 @@ def checkout(repo: git.Repo, ref: str, force: bool = False) -> None:
         VersionControlError: Check out failed.
     """
     try:
-        repo.git.checkout(f"--force {ref}" if force else str(ref))
+        git_args = [ref] + ["--force"] if force else [ref]
+        repo.git.checkout(*git_args)
     except git.exc.GitCommandError as err:
         raise VersionControlError(f"Failed to check out revision '{ref}'. Error from VCS: {err}")
 

tests/project/_internal/test_git_utils.py

@@ -84,9 +84,14 @@ def test_raises_version_control_error_when_no_git_repo_found(self, mock_repo):
 
 class TestCheckout:
     def test_git_lib_called_with_correct_command(self, mock_repo):
+        git_utils.checkout(mock_repo, "master")
+
+        mock_repo.git.checkout.assert_called_once_with("master")
+
+    def test_git_lib_called_with_correct_command_with_force(self, mock_repo):
         git_utils.checkout(mock_repo, "master", force=True)
 
-        mock_repo.git.checkout.assert_called_once_with("--force master")
+        mock_repo.git.checkout.assert_called_once_with("master", "--force")
 
     def test_raises_version_control_error_when_git_checkout_fails(self, mock_repo):
         mock_repo.git.checkout.side_effect = git_utils.git.exc.GitCommandError("git checkout", 255)