test_pages_layout.py

import pytest
import dash
from dash import Dash, dcc, html
from dash.exceptions import NoLayoutException


def get_app(path1="/", path2="/layout2"):
    app = Dash(__name__, use_pages=True)

    # test for storing arbitrary keyword arguments: An `id` prop is defined for every page
    # test for defining multiple pages within a single file: layout is passed directly to `register_page`
    # in the following two modules:
    dash.register_page(
        "multi_layout1",
        layout=html.Div("text for multi_layout1", id="text_multi_layout1"),
        path=path1,
        title="Supplied Title",
        description="This is the supplied description",
        name="Supplied name",
        image="birds.jpeg",
        id="multi_layout1",
    )
    dash.register_page(
        "multi_layout2",
        layout=html.Div("text for multi_layout2", id="text_multi_layout2"),
        path=path2,
        id="multi_layout2",
    )

    app.layout = html.Div(
        [
            html.Div(
                [
                    html.Div(
                        dcc.Link(
                            f"{page['name']} - {page['path']}",
                            id=page["id"],
                            href=page["path"],
                        )
                    )
                    for page in dash.page_registry.values()
                ]
            ),
            dash.page_container,
            dcc.Location(id="url", refresh=True),
        ]
    )
    return app


def test_pala001_layout(dash_duo):

    dash_duo.start_server(get_app())

    # test layout and title for each page in `page_registry` with link navigation
    for page in dash.page_registry.values():
        dash_duo.find_element("#" + page["id"]).click()
        dash_duo.wait_for_text_to_equal("#text_" + page["id"], "text for " + page["id"])
        assert dash_duo.driver.title == page["title"], "check that page title updates"

    # test redirects
    dash_duo.wait_for_page(url=f"http://localhost:{dash_duo.server.port}/v2")
    dash_duo.wait_for_text_to_equal("#text_redirect", "text for redirect")
    dash_duo.wait_for_page(url=f"http://localhost:{dash_duo.server.port}/old-home-page")
    dash_duo.wait_for_text_to_equal("#text_redirect", "text for redirect")
    assert (
        dash_duo.driver.current_url
        == f"http://localhost:{dash_duo.server.port}/redirect"
    )

    # test redirect with button and user defined dcc.Location
    # note:  dcc.Location must be defined in app.py
    dash_duo.wait_for_page(url=f"http://localhost:{dash_duo.server.port}/page1")
    dash_duo.find_element("#btn1").click()
    dash_duo.wait_for_text_to_equal("#text_page2", "text for page2")

    # test query strings
    dash_duo.wait_for_page(
        url=f"http://localhost:{dash_duo.server.port}/query-string?velocity=10"
    )
    assert (
        dash_duo.find_element("#velocity").get_attribute("value") == "10"
    ), "query string passed to layout"

    # test path variables
    dash_duo.wait_for_page(url=f"http://localhost:{dash_duo.server.port}/a/none/b/none")
    dash_duo.wait_for_text_to_equal("#path_vars", "variables from pathname:none none")

    dash_duo.wait_for_page(url=f"http://localhost:{dash_duo.server.port}/a/var1/b/var2")
    dash_duo.wait_for_text_to_equal("#path_vars", "variables from pathname:var1 var2")

    # test page not found
    dash_duo.wait_for_page(url=f"http://localhost:{dash_duo.server.port}/find_me")
    dash_duo.wait_for_text_to_equal("#text_not_found_404", "text for not_found_404")

    assert dash_duo.get_logs() == [], "browser console should contain no error"
    # dash_duo.percy_snapshot("pala001_layout")


def check_metas(dash_duo, metas):
    meta = dash_duo.find_elements("meta")

    # -3 for the meta charset and http-equiv and viewport.
    assert len(meta) == len(metas) + 3, "Should have  extra meta tags"

    assert meta[0].get_attribute("name") == metas[0]["name"]
    assert meta[0].get_attribute("content") == metas[0]["content"]
    for i in range(1, len(meta) - 3):
        assert meta[i].get_attribute("property") == metas[i]["property"]
        assert meta[i].get_attribute("content") == metas[i]["content"]


def test_pala002_meta_tags_default(dash_duo):
    dash_duo.start_server(get_app(path1="/layout1", path2="/"))
    # These are the inferred defaults if description, title, image are not supplied
    metas_layout2 = [
        {"name": "description", "content": ""},
        {"property": "twitter:card", "content": "summary_large_image"},
        {
            "property": "twitter:url",
            "content": f"http://localhost:{dash_duo.server.port}/",
        },
        {"property": "twitter:title", "content": "Multi layout2"},
        {"property": "twitter:description", "content": ""},
        {
            "property": "twitter:image",
            "content": f"http://localhost:{dash_duo.server.port}/assets/app.jpeg",
        },
        {"property": "og:title", "content": "Multi layout2"},
        {"property": "og:type", "content": "website"},
        {"property": "og:description", "content": ""},
        {
            "property": "og:image",
            "content": f"http://localhost:{dash_duo.server.port}/assets/app.jpeg",
        },
    ]

    check_metas(dash_duo, metas_layout2)


def test_pala003_meta_tags_custom(dash_duo):
    dash_duo.start_server(get_app())
    # In the "multi_layout1" module, the description, title, image are supplied
    metas_layout1 = [
        {"name": "description", "content": "This is the supplied description"},
        {"property": "twitter:card", "content": "summary_large_image"},
        {
            "property": "twitter:url",
            "content": f"http://localhost:{dash_duo.server.port}/",
        },
        {"property": "twitter:title", "content": "Supplied Title"},
        {
            "property": "twitter:description",
            "content": "This is the supplied description",
        },
        {
            "property": "twitter:image",
            "content": f"http://localhost:{dash_duo.server.port}/assets/birds.jpeg",
        },
        {"property": "og:title", "content": "Supplied Title"},
        {"property": "og:type", "content": "website"},
        {"property": "og:description", "content": "This is the supplied description"},
        {
            "property": "og:image",
            "content": f"http://localhost:{dash_duo.server.port}/assets/birds.jpeg",
        },
    ]

    check_metas(dash_duo, metas_layout1)


def test_pala004_no_layout_exception():
    error_msg = 'No layout found in module pages_error.no_layout_page\nA variable or a function named "layout" is required.'

    with pytest.raises(NoLayoutException) as err:
        Dash(__name__, use_pages=True, pages_folder="pages_error")

    # clean up after this test, so the broken entry doesn't affect other pages tests
    del dash.page_registry["pages_error.no_layout_page"]

    assert error_msg in err.value.args[0]