fix test error

Author: klamike

test/test_cli.py

@@ -83,18 +83,21 @@ def test_basic_usage(self, runner):
     def test_error_handling_with_fake_package(self, fake_package_test):
         runner = fake_package_test
 
-        result = runner.invoke(cli, ["resolve", "--force"])
+        result = runner.invoke(cli, ["resolve"])
         assert result.exit_code != 0
         assert not isinstance(result.exception, subprocess.CalledProcessError)
 
         k = "JULIAPKG_ALWAYS_SHOW_PYTHON_ERROR_CLI"
-        old_k, os.environ[k] = os.environ[k], "1"
+        old_k, os.environ[k] = os.environ.get(k, None), "1"
         try:
-            result = runner.invoke(cli, ["resolve", "--force"])
+            result = runner.invoke(cli, ["resolve"])
             assert result.exit_code != 0
             assert isinstance(result.exception, subprocess.CalledProcessError)
         finally:
-            os.environ[k] = old_k
+            if old_k is None:
+                del os.environ[k]
+            else:
+                os.environ[k] = old_k
 
     def test_click_not_available(self):
         with patch.dict(sys.modules, {"click": None}):