datasette --get status code for error pages, closes #947

datasette/cli.py

@@ -444,6 +444,8 @@ def serve(
         client = TestClient(ds.app())
         response = client.get(get)
         click.echo(response.text)
+        exit_code = 0 if response.status == 200 else 1
+        sys.exit(exit_code)
         return
 
     # Start the server

docs/getting_started.rst

@@ -155,6 +155,8 @@ The ``--get`` option can specify the path to a page within Datasette and cause D
       }
     }
 
+The exit code will be 0 if the request succeeds and 1 if the request produced an HTTP status code other than 200 - e.g. a 404 or 500 error. This means you can use ``datasette --get /`` to run tests against a Datasette application in a continuous integration environment such as GitHub Actions.
+
 .. _getting_started_serve_help:
 
 datasette serve --help

tests/test_cli_serve_get.py

@@ -39,6 +39,7 @@ def test_serve_with_get(tmp_path_factory):
         "truncated": False,
         "columns": ["sqlite_version()"],
     }.items() <= json.loads(result.output).items()
+
     # The plugin should have created hello.txt
     assert (plugins_dir / "hello.txt").read_text() == "hello"
 
@@ -48,3 +49,18 @@ def test_serve_with_get(tmp_path_factory):
         p for p in pm.get_plugins() if p.__name__ == "init_for_serve_with_get.py"
     ][0]
     pm.unregister(to_unregister)
+
+
+def test_serve_with_get_exit_code_for_error(tmp_path_factory):
+    runner = CliRunner()
+    result = runner.invoke(
+        cli,
+        [
+            "serve",
+            "--memory",
+            "--get",
+            "/this-is-404",
+        ],
+    )
+    assert result.exit_code == 1
+    assert "404" in result.output