feat: Save selected language into cookie

Refs: #1

src/atsphinx/mini18n/templates/mini18n/snippets/select-lang.html

@@ -6,9 +6,13 @@
   </style>
   <div>
     <label for="atsphinx-mini18n-select-lang">{{ mini18n.select_lang_label }}</label>
-    <select name="lang" onchange="location.href=value;" id="atsphinx-mini18n-select-lang">
+    <select name="lang" onchange="{
+                        const values = value.split('@@');
+                        document.cookie = `lang=${values[0]}; path=/; samesite=Strict; max-age=${60*60*24*400};`;
+                        location.href=values[1];
+                        }" id="atsphinx-mini18n-select-lang">
       {%- for code in mini18n.support_languages %}
-      <option value="{{ pathto('../' + code + '/', 1) }}{{ pathto(pagename, 0, '.') }}" {%- if code==language %}
+      <option value="{{ code }}@@{{ pathto('../' + code + '/', 1) }}{{ pathto(pagename, 0, '.') }}" {%- if code==language %}
         selected {%- endif %}>{{ code }}</option>
       {%- endfor %}
     </select>

tests/test-e2e/conf.py

@@ -1,8 +1,11 @@
 # noqa: D100
+from atsphinx.mini18n import get_template_dir
 
 extensions = [
     "atsphinx.mini18n",
 ]
 
+html_sidebars = {"**": [f"{get_template_dir()}/mini18n/snippets/select-lang.html"]}
+
 mini18n_default_language = "en"
 mini18n_support_languages = ["en", "ja"]

tests/test_javascript.py

@@ -57,3 +57,24 @@ def test__root(app: SphinxTestApp, page: Page):
         page.goto(url)
         time.sleep(0.5)
         assert page.url.endswith("/en/")
+
+
+@pytest.mark.sphinx("mini18n-html", testroot="e2e")
+def test__select_language(app: SphinxTestApp, page: Page):
+    app.build()
+    with ServerOnPytest(app.outdir) as server:
+        url = f"http://localhost:{server.port}/"
+        page.goto(url)
+        time.sleep(0.5)
+        assert page.url.endswith("/en/")
+        assert not page.context.cookies()
+        element = page.get_by_label("Language:")
+        element.select_option(label="ja")
+        element.evaluate(
+            "elm => elm.dispatchEvent(new Event('change', {bubbles: true}))"
+        )
+        time.sleep(0.5)
+        assert page.url.endswith("/ja/index.html")
+        cookies = page.context.cookies()
+        assert cookies[0]["name"] == "lang"
+        assert cookies[0]["value"] == "ja"