Handle blank database URLs

dslr/cli.py

@@ -70,7 +70,11 @@ def cli(url, debug):
     }
 
     # Update the settings singleton
-    settings.initialize(**config)
+    try:
+        settings.initialize(**config)
+    except ValueError as e:
+        eprint(e, style="red")
+        sys.exit(1)
 
 
 @cli.command()

dslr/config.py

@@ -23,6 +23,12 @@ def initialize(self, *, url: str, debug: bool):
         self.url = url
         self.debug = debug
 
+        if not self.url:
+            raise ValueError(
+                "No database URL specified. Please pass it via the --url option, "
+                'the DATABASE_URL environment variable, or a "dslr.toml" file.'
+            )
+
         parsed = urlparse(url)
 
         self.db = DatabaseConnection(

tests/test_cli.py

@@ -257,13 +257,16 @@ def test_db_option(self, mock_cli_settings, mock_get_snapshots):
             url="postgres://cli:pw@test:5432/my_db",
         )
 
-    @mock.patch("dslr.cli.settings")
-    def test_settings_preference_order(self, mock_cli_settings, mock_get_snapshots):
-        # No options passed (e.g. PG environment variables are used)
+    @mock.patch.dict(os.environ, {}, clear=True)
+    def test_no_url(self, mock_get_snapshots):
         runner = CliRunner()
         result = runner.invoke(cli.cli, ["list"])
-        self.assertEqual(result.exit_code, 0)
 
+        self.assertEqual(result.exit_code, 1)
+        self.assertIn("No database URL specified", result.output)
+
+    @mock.patch("dslr.cli.settings")
+    def test_settings_preference_order(self, mock_cli_settings, mock_get_snapshots):
         # DATABASE_URL environment variable is used
         with mock.patch.dict(
             os.environ, {"DATABASE_URL": "postgres://envvar:pw@test:5432/my_db"}
@@ -272,31 +275,29 @@ def test_settings_preference_order(self, mock_cli_settings, mock_get_snapshots):
             result = runner.invoke(cli.cli, ["list"])
             self.assertEqual(result.exit_code, 0)
 
-            # TOML file is used
-            with mock.patch(
-                "builtins.open",
-                mock.mock_open(read_data=b"url = 'postgres://toml:pw@test:5432/my_db'"),
-            ):
-                runner = CliRunner()
-                result = runner.invoke(cli.cli, ["list"])
-                self.assertEqual(result.exit_code, 0)
-
-                # --url option is used
-                runner = CliRunner()
-                result = runner.invoke(
-                    cli.cli,
-                    ["--url", "postgres://cli:pw@test:5432/my_db", "list"],
-                )
-                self.assertEqual(result.exit_code, 0)
+        # TOML file is used
+        with mock.patch(
+            "builtins.open",
+            mock.mock_open(read_data=b"url = 'postgres://toml:pw@test:5432/my_db'"),
+        ):
+            runner = CliRunner()
+            result = runner.invoke(cli.cli, ["list"])
+            self.assertEqual(result.exit_code, 0)
+
+        # --url option is used
+        runner = CliRunner()
+        result = runner.invoke(
+            cli.cli,
+            ["--url", "postgres://cli:pw@test:5432/my_db", "list"],
+        )
+        self.assertEqual(result.exit_code, 0)
 
         # Check that the correct order of settings is used
-        self.assertEqual(4, mock_cli_settings.initialize.call_count)
+        self.assertEqual(3, mock_cli_settings.initialize.call_count)
 
         self.assertEqual(
             mock_cli_settings.initialize.call_args_list,
             [
-                # Nothing is passed
-                mock.call(debug=False, url=""),
                 # DATABASE_URL is present so use that
                 mock.call(debug=False, url="postgres://envvar:pw@test:5432/my_db"),
                 # TOML is present, so use that over DATABASE_URL