Introduce assert_component_equal for tests

vizro-core/changelog.d/20231219_171218_antony.milne_assert_components_equal.md

@@ -0,0 +1,48 @@
+<!--
+A new scriv changelog fragment.
+
+Uncomment the section that is right (remove the HTML comment wrapper).
+-->
+
+<!--
+### Highlights ✨
+
+- A bullet item for the Highlights ✨ category with a link to the relevant PR at the end of your entry, e.g. Enable feature XXX ([#1](https://github.com/mckinsey/vizro/pull/1))
+
+-->
+<!--
+### Removed
+
+- A bullet item for the Removed category with a link to the relevant PR at the end of your entry, e.g. Enable feature XXX ([#1](https://github.com/mckinsey/vizro/pull/1))
+
+-->
+<!--
+### Added
+
+- A bullet item for the Added category with a link to the relevant PR at the end of your entry, e.g. Enable feature XXX ([#1](https://github.com/mckinsey/vizro/pull/1))
+
+-->
+<!--
+### Changed
+
+- A bullet item for the Changed category with a link to the relevant PR at the end of your entry, e.g. Enable feature XXX ([#1](https://github.com/mckinsey/vizro/pull/1))
+
+-->
+<!--
+### Deprecated
+
+- A bullet item for the Deprecated category with a link to the relevant PR at the end of your entry, e.g. Enable feature XXX ([#1](https://github.com/mckinsey/vizro/pull/1))
+
+-->
+<!--
+### Fixed
+
+- A bullet item for the Fixed category with a link to the relevant PR at the end of your entry, e.g. Enable feature XXX ([#1](https://github.com/mckinsey/vizro/pull/1))
+
+-->
+<!--
+### Security
+
+- A bullet item for the Security category with a link to the relevant PR at the end of your entry, e.g. Enable feature XXX ([#1](https://github.com/mckinsey/vizro/pull/1))
+
+-->

vizro-core/src/vizro/models/_components/button.py

@@ -32,13 +32,7 @@ class Button(VizroBaseModel):
     @_log_call
     def build(self):
         return html.Div(
-            [
-                dbc.Button(
-                    id=self.id,
-                    children=self.text,
-                    className="button_primary",
-                ),
-            ],
+            dbc.Button(id=self.id, children=self.text, className="button_primary"),
             className="button_container",
             id=f"{self.id}_outer",
         )

vizro-core/tests/integration/test_navigation.py

@@ -151,4 +151,4 @@ def label_cases(cases, label):
 def test_navigation_build(dashboard_result, dashboard_expected):
     result = dashboard_result.navigation.build()
     expected = dashboard_expected.navigation.build()
-    assert_component_equal(result, expected)
+    assert_component_equal(result, expected, keys_to_strip={"id"})

vizro-core/tests/tests_utils/asserts.py

@@ -3,28 +3,41 @@
 import dash.development
 import plotly
 
+STRIP_ALL = object()
 
-def strip_keys(object, keys):
-    """Strips all entries with key "id" from a dictionary, regardless of how deeply it's nested.
 
-    This makes it easy to compare dictionaries generated from Dash components we've created that contain random IDs.
-    """
+def _strip_keys(object, keys):
+    """Strips from a JSON object all entries where the key is in keys, regardless of how deeply it's nested."""
     if isinstance(object, dict):
-        object = {key: strip_keys(value, keys) for key, value in object.items() if key not in keys}
+        object = {key: _strip_keys(value, keys) for key, value in object.items() if key not in keys}
     elif isinstance(object, list):
-        object = [strip_keys(item, keys) for item in object]
+        object = [_strip_keys(item, keys) for item in object]
     return object
 
 
-def component_to_dict(component: dash.development.base_component.Component) -> dict:
+def _component_to_dict(component: dash.development.base_component.Component) -> dict:
+    """Prepares a Dash component for comparison by conversion to JSON object."""
     return json.loads(json.dumps(component, cls=plotly.utils.PlotlyJSONEncoder))
 
 
-# TODO: implement some sort of depth limit to comparison so can use in high level tests, roll out more widely across
-# tests
-def assert_component_equal(left, right, keys_to_strip=None):
-    # Note we check for None explicitly because {} is a valid value for keys_to_strip.
-    keys_to_strip = keys_to_strip if keys_to_strip is not None else {"id", "class_name", "className"}
-    left = strip_keys(component_to_dict(left), keys_to_strip)
-    right = strip_keys(component_to_dict(right), keys_to_strip)
+def assert_component_equal(left, right, *, keys_to_strip=None):
+    """Checks that the left and right Dash components are equal, ignoring keys_to_strip.
+
+    If keys_to_strip is set to STRIP_ALL then only the type and namespace of component
+    will be compared, similar to doing isinstance.
+
+    Examples:
+        >>> from dash import html
+        >>> assert_component_equal(html.Div(), html.Div())
+        >>> assert_component_equal(html.Div(id="a"), html.Div(), keys_to_strip={"id"})
+        >>> assert_component_equal(html.Div([html.P(), html.P()], id="a"), html.Div(id="a"), keys_to_strip={"children"})
+        >>> assert_component_equal(html.Div(html.P(), className="blah", id="a"), html.Div(), keys_to_strip=STRIP_ALL)
+    """
+    keys_to_strip = keys_to_strip or {}
+    if keys_to_strip is STRIP_ALL:
+        # Remove all properties from the component dictionary, leaving just "type" and "namespace" behind.
+        keys_to_strip = {"props"}
+
+    left = _strip_keys(_component_to_dict(left), keys_to_strip)
+    right = _strip_keys(_component_to_dict(right), keys_to_strip)
     assert left == right

vizro-core/tests/tests_utils/demo_asserts.py

@@ -0,0 +1,48 @@
+"""Demo to show how to use asserts. These are not real tests that are run as part of testing, just a teaching aid."""
+from typing import List
+
+from asserts import STRIP_ALL, assert_component_equal
+from dash import html
+
+from vizro.models import VizroBaseModel
+
+
+class X(VizroBaseModel):
+    # Low-level contents model.
+    text: str
+
+    def build(self):
+        return html.Div(
+            [html.H1("Heading"), html.P(self.text, id=self.id), html.Hr(), html.H2("Something")], className="inner"
+        )
+
+
+class Y(VizroBaseModel):
+    # Higher-level container model.
+    children: List[X]
+
+    def build(self):
+        return html.Div([child.build() for child in self.children], id=self.id, className="container")
+
+
+def test_X_build():
+    # Test for low-level contents: compare the whole component tree.
+    # Sometimes setting keys_to_strip={"className"} is useful here.
+    result = X(id="x", text="Hello world").build()
+    expected = html.Div(
+        [html.H1("Heading"), html.P("Hello world", id="x"), html.Hr(), html.H2("Something")], className="inner"
+    )
+    assert_component_equal(result, expected)
+
+
+def test_Y_build():
+    # Test for higher-level container.
+    many_x = [X(text="Hello world") for _ in range(4)]
+    result = Y(id="y", children=many_x).build()
+    # We don't want to compare the whole component tree here. Instead compare the bit that's specifically in Y and
+    # ignore the children:
+    assert_component_equal(result, html.Div(id="y", className="container"), keys_to_strip={"children"})
+    # And also compare the "interface" between X and Y. Use STRIP_ALL to not look at any properties of the html.Div.
+    # This is basically the same as doing:
+    # assert all(isinstance(child, html.Div) for child in result.children) and len(result.children) == 4
+    assert_component_equal(result.children, [html.Div()] * 4, keys_to_strip=STRIP_ALL)

vizro-core/tests/unit/vizro/models/_components/test_button.py

@@ -1,30 +1,14 @@
 """Unit tests for vizro.models.Button."""
-import json
 
 import dash_bootstrap_components as dbc
-import plotly
 import pytest
+from asserts import assert_component_equal
 from dash import html
 
 import vizro.models as vm
 from vizro.actions import export_data
 
 
-@pytest.fixture
-def expected_button():
-    return html.Div(
-        [
-            dbc.Button(
-                id="button_id",
-                children="Click me!",
-                className="button_primary",
-            ),
-        ],
-        className="button_container",
-        id="button_id_outer",
-    )
-
-
 class TestButtonInstantiation:
     """Tests model instantiation and the validators run at that time."""
 
@@ -53,9 +37,11 @@ def test_set_action_via_validator(self):
 
 
 class TestBuildMethod:
-    def test_button_build(self, expected_button):
-        button = vm.Button(id="button_id", text="Click me!").build()
-        result = json.loads(json.dumps(button, cls=plotly.utils.PlotlyJSONEncoder))
-        expected = json.loads(json.dumps(expected_button, cls=plotly.utils.PlotlyJSONEncoder))
-
-        assert result == expected
+    def test_button_build(self):
+        button = vm.Button(id="button_id", text="My text").build()
+        expected = html.Div(
+            dbc.Button(id="button_id", children="My text", className="button_primary"),
+            className="button_container",
+            id="button_id_outer",
+        )
+        assert_component_equal(button, expected)

vizro-core/tests/unit/vizro/models/_navigation/test_accordion.py

@@ -55,7 +55,7 @@ def test_invalid_page(self, pages):
 class TestAccordionBuild:
     """Tests accordion build method."""
 
-    common_args = {"always_open": True, "persistence": True, "persistence_type": "session"}
+    common_args = {"always_open": True, "persistence": True, "persistence_type": "session", "id": "accordion"}
 
     test_cases = [
         (
@@ -113,9 +113,11 @@ class TestAccordionBuild:
     @pytest.mark.parametrize("pages, expected", test_cases)
     def test_accordion(self, pages, expected):
         accordion = vm.Accordion(id="accordion", pages=pages).build(active_page_id="Page 1")
-        assert_component_equal(accordion, html.Div(id="nav_panel_outer"), keys_to_strip={"children", "className"})
-        assert_component_equal(accordion["accordion"], expected)
+        assert_component_equal(
+            accordion, html.Div(id="nav_panel_outer", className="nav_panel"), keys_to_strip={"children"}
+        )
+        assert_component_equal(accordion["accordion"], expected, keys_to_strip={"class_name", "className"})
 
     def test_accordion_one_page(self):
         accordion = vm.Accordion(pages={"Group": ["Page 1"]}).build(active_page_id="Page 1")
-        assert_component_equal(accordion, html.Div(hidden=True, id="nav_panel_outer"), keys_to_strip={})
+        assert_component_equal(accordion, html.Div(hidden=True, id="nav_panel_outer"))

vizro-core/tests/unit/vizro/models/_navigation/test_nav_bar.py

@@ -4,7 +4,7 @@
 import dash_bootstrap_components as dbc
 import dash_mantine_components as dmc
 import pytest
-from asserts import assert_component_equal
+from asserts import STRIP_ALL, assert_component_equal
 from dash import html
 
 try:
@@ -93,11 +93,13 @@ def test_nav_bar_active_pages_as_dict(self, pages_as_dict):
                 )
             ]
         )
-        assert_component_equal(built_nav_bar["nav_bar_outer"], expected_button)
+        assert_component_equal(built_nav_bar["nav_bar_outer"], expected_button, keys_to_strip={"id", "className"})
         assert_component_equal(
-            built_nav_bar["nav_panel_outer"], html.Div(id="nav_panel_outer"), keys_to_strip={"children", "className"}
+            built_nav_bar["nav_panel_outer"],
+            html.Div(id="nav_panel_outer", className="nav_panel"),
+            keys_to_strip={"children"},
         )
-        assert all(isinstance(child, dbc.Accordion) for child in built_nav_bar["nav_panel_outer"].children)
+        assert_component_equal(built_nav_bar["nav_panel_outer"].children, [dbc.Accordion()], keys_to_strip=STRIP_ALL)
 
     def test_nav_bar_active_pages_as_list(self, pages_as_list):
         nav_bar = vm.NavBar(pages=pages_as_list)
@@ -117,11 +119,10 @@ def test_nav_bar_active_pages_as_list(self, pages_as_list):
                 ),
             ]
         )
-        assert_component_equal(built_nav_bar["nav_bar_outer"], expected_buttons)
+        assert_component_equal(built_nav_bar["nav_bar_outer"], expected_buttons, keys_to_strip={"id", "className"})
         assert_component_equal(
             built_nav_bar["nav_panel_outer"],
             html.Div(id="nav_panel_outer", hidden=True),
-            keys_to_strip={"children", "className"},
         )
 
     def test_nav_bar_not_active_pages_as_dict(self, pages_as_dict):
@@ -137,10 +138,8 @@ def test_nav_bar_not_active_pages_as_dict(self, pages_as_dict):
                 )
             ]
         )
-        assert_component_equal(built_nav_bar["nav_bar_outer"], expected_button)
-        assert_component_equal(
-            built_nav_bar["nav_panel_outer"], html.Div(hidden=True, id="nav_panel_outer"), keys_to_strip={}
-        )
+        assert_component_equal(built_nav_bar["nav_bar_outer"], expected_button, keys_to_strip={"id", "className"})
+        assert_component_equal(built_nav_bar["nav_panel_outer"], html.Div(hidden=True, id="nav_panel_outer"))
 
     def test_nav_bar_not_active_pages_as_list(self, pages_as_list):
         nav_bar = vm.NavBar(pages=pages_as_list)
@@ -160,9 +159,8 @@ def test_nav_bar_not_active_pages_as_list(self, pages_as_list):
                 ),
             ]
         )
-        assert_component_equal(built_nav_bar["nav_bar_outer"], expected_buttons)
+        assert_component_equal(built_nav_bar["nav_bar_outer"], expected_buttons, keys_to_strip={"id", "className"})
         assert_component_equal(
             built_nav_bar["nav_panel_outer"],
             html.Div(id="nav_panel_outer", hidden=True),
-            keys_to_strip={},
         )

vizro-core/tests/unit/vizro/models/_navigation/test_nav_link.py

@@ -4,7 +4,7 @@
 import dash_bootstrap_components as dbc
 import dash_mantine_components as dmc
 import pytest
-from asserts import assert_component_equal
+from asserts import STRIP_ALL, assert_component_equal
 from dash import html
 
 try:
@@ -86,22 +86,38 @@ def test_nav_link_active(self, pages, request):
         nav_link.pre_build()
         built_nav_link = nav_link.build(active_page_id="Page 1")
         expected_button = dbc.Button(
-            children=[dmc.Tooltip(label="Label", children=[html.Span("icon")], **self.common_args)],
+            children=[
+                dmc.Tooltip(
+                    label="Label",
+                    children=[html.Span("icon", className="material-symbols-outlined")],
+                    **self.common_args,
+                )
+            ],
             active=True,
             href="/",
+            className="icon-button",
+            id="nav_link",
         )
         assert_component_equal(built_nav_link["nav_link"], expected_button)
-        assert all(isinstance(child, dbc.Accordion) for child in built_nav_link["nav_panel_outer"].children)
+        assert_component_equal(built_nav_link["nav_panel_outer"].children, [dbc.Accordion()], keys_to_strip=STRIP_ALL)
 
     def test_nav_link_not_active(self, pages, request):
         pages = request.getfixturevalue(pages)
         nav_link = vm.NavLink(id="nav_link", label="Label", icon="icon", pages=pages)
         nav_link.pre_build()
         built_nav_link = nav_link.build(active_page_id="Page 3")
         expected_button = dbc.Button(
-            children=[dmc.Tooltip(label="Label", children=[html.Span("icon")], **self.common_args)],
+            children=[
+                dmc.Tooltip(
+                    label="Label",
+                    children=[html.Span("icon", className="material-symbols-outlined")],
+                    **self.common_args,
+                )
+            ],
             active=False,
             href="/",
+            className="icon-button",
+            id="nav_link",
         )
         assert_component_equal(built_nav_link["nav_link"], expected_button)
         assert "nav_panel_outer" not in built_nav_link