Add integration tests for frontend path

reflex/environment.py

@@ -640,6 +640,9 @@ class EnvironmentVariables:
     # Enable full logging of debug messages to reflex user directory.
     REFLEX_ENABLE_FULL_LOGGING: EnvVar[bool] = env_var(False)
 
+    # The path underwhich the frontend is served.
+    REFLEX_FRONTEND_PATH: EnvVar[str] = env_var("")
+
 
 environment = EnvironmentVariables()
 

tests/integration/tests_playwright/test_frontend_path.py

@@ -0,0 +1,105 @@
+from collections.abc import Generator
+
+import pytest
+from playwright.sync_api import Page, expect
+
+from reflex.environment import environment
+from reflex.testing import AppHarness, AppHarnessProd
+
+
+def OnLoadRedirectApp():
+    import reflex as rx
+
+    @rx.page("/")
+    def index():
+        return rx.container(
+            rx.input(
+                value=rx.State.router.session.client_token,
+                read_only=True,
+                id="token",
+            ),
+            rx.vstack(
+                rx.heading("This is the index page!"),
+                rx.button("Go to Subpage!", on_click=rx.redirect("/subpage")),
+            ),
+        )
+
+    @rx.page("/subpage")
+    def subpage():
+        return rx.container(
+            rx.vstack(
+                rx.heading("This is the sub page!"),
+                rx.button("Go to index!", on_click=rx.redirect("/")),
+                rx.button("Bounce to index!", on_click=rx.redirect("/bouncer")),
+            )
+        )
+
+    @rx.page("/bouncer", on_load=rx.redirect("/"))
+    def bouncer():
+        return rx.container(
+            rx.vstack(
+                rx.heading("This is the bouncer page!"),
+                rx.text("You should not be here!"),
+                rx.button("Go to index!", on_click=rx.redirect("/")),
+            ),
+        )
+
+    app = rx.App()  # noqa: F841
+
+
+@pytest.fixture
+def onload_redirect_app(tmp_path_factory) -> Generator[AppHarness, None, None]:
+    with AppHarnessProd.create(
+        root=tmp_path_factory.mktemp("frontend_path_app"),
+        app_source=OnLoadRedirectApp,
+    ) as harness:
+        assert harness.app_instance is not None, "app is not running"
+        yield harness
+
+
+@pytest.fixture
+def onload_redirect_with_prefix_app(
+    tmp_path_factory,
+) -> Generator[AppHarness, None, None]:
+    prefix = "/prefix"
+    environment.REFLEX_FRONTEND_PATH.set(prefix)
+    with AppHarness.create(
+        root=tmp_path_factory.mktemp("frontend_path_app"),
+        app_source=OnLoadRedirectApp,
+    ) as harness:
+        assert harness.app_instance is not None, "app is not running"
+        yield harness
+    environment.REFLEX_FRONTEND_PATH.set("")
+
+
+@pytest.mark.parametrize(
+    ("app_fixture_name", "prefix"),
+    [
+        ("onload_redirect_app", ""),
+        pytest.param(
+            "onload_redirect_with_prefix_app",
+            "/prefix",
+            marks=pytest.mark.xfail(reason="bug #5674"),
+        ),
+    ],
+)
+def test_onload_redirect(app_fixture_name: str, prefix: str, page: Page, request):
+    app_fixture = request.getfixturevalue(app_fixture_name)
+    assert app_fixture.frontend_url is not None
+
+    base_url = app_fixture.frontend_url.rstrip("/")
+    base_url += prefix
+    page.goto(f"{base_url}/")
+    expect(page.get_by_text("This is the index page!")).to_be_visible()
+
+    # Go to /subpage
+    page.get_by_text("Go to Subpage!").click()
+    expect(page.get_by_text("This is the sub page!")).to_be_visible()
+
+    # Click "Bounce to index!" (should redirect to index via on_load)
+    page.get_by_text("Bounce to index!").click()
+    expect(page.get_by_text("This is the index page!")).to_be_visible()
+
+    # Optionally, reload /prefix/bouncer/ and check redirect
+    page.goto(f"{base_url}/bouncer/")
+    expect(page.get_by_text("This is the index page!")).to_be_visible()