fix(instances): the VM page opens the tab a redirect points to, and host links are for administrators

Redirects to #access (root password, SSH key) and other top-level panes
opened nothing, and some sub-tab ids did not exist. static/js/instance_tabs.js
opens the pane and the tab that holds it from the page structure, and
opens Settings on its first section, without leaving the current tab;
guest OS info is loaded whenever it is the section opened. The bottom bar linked to
host pages, which only administrators may open, and showed host names to
everyone. A stray </li> is removed; the page's inline scripts and the tab
logic are checked with Node.

webvirtcloud/js_tests/instance_tabs.test.js

@@ -0,0 +1,77 @@
+// node instance_tabs.test.js path/to/static/js/instance_tabs.js
+const assert = require("assert");
+const {restoreInstanceTab} = require(process.argv[2]);
+
+// A minimal DOM: elements with an id, classes, a parent, children, and the
+// few selectors restoreInstanceTab uses.
+function el(id, classes, children = [], attrs = {}) {
+    const node = {id, classList: new Set(classes), children, attrs, parentElement: null};
+    node.classList.contains = (c) => node.classList.has(c);
+    node.getAttribute = (name) => attrs[name];
+    for (const child of children) child.parentElement = node;
+    node.querySelector = (selector) => find(node, selector);
+    return node;
+}
+
+function* walk(node) {
+    for (const child of node.children) {
+        yield child;
+        yield* walk(child);
+    }
+}
+
+function matches(node, selector) {
+    if (selector === ".nav-tabs") return node.classList.has("nav-tabs");
+    if (selector === ".nav-link.active") return node.classList.has("nav-link") && node.classList.has("active");
+    if (selector === ".nav-link:not(#osinfo-tab)") return node.classList.has("nav-link") && node.id !== "osinfo-tab";
+    if (selector === "#osinfo-tab") return node.id === "osinfo-tab";
+    throw new Error("unsupported selector " + selector);
+}
+
+function find(root, selector) {
+    for (const node of walk(root)) if (matches(node, selector)) return node;
+    return null;
+}
+
+function link(target, extra = []) {
+    return el(target === "#osinfo" ? "osinfo-tab" : "", ["nav-link", ...extra], [], {"data-bs-target": target});
+}
+
+// The VM page: top-level panes, Settings with its own tabs and panes.
+function page(settingsLinks) {
+    const settings = el("settings", ["tab-pane"], [
+        el("", ["nav-tabs"], settingsLinks),
+        el("", ["tab-content"], [el("osinfo", ["tab-pane"]), el("options", ["tab-pane"]), el("vncsettings", ["tab-pane"])]),
+    ]);
+    const root = el("", [], [el("", ["tab-content"], [el("power", ["tab-pane", "active"]), el("access", ["tab-pane"]), settings])]);
+    root.getElementById = (id) => {
+        for (const node of walk(root)) if (node.id === id) return node;
+        return null;
+    };
+    return root;
+}
+
+function run(doc, hash) {
+    const shown = [];
+    let loaded = 0;
+    restoreInstanceTab(doc, hash, (target) => shown.push(target), () => loaded++);
+    return {shown, loaded};
+}
+
+const settled = () => page([link("#options", ["active"])]);
+
+// a top-level pane opens directly
+assert.deepStrictEqual(run(settled(), "#access").shown, ["#access"]);
+// a pane inside Settings opens Settings first
+assert.deepStrictEqual(run(settled(), "#options").shown, ["#settings", "#options"]);
+// no hash, an unknown one, or one with odd characters opens nothing
+for (const hash of ["", "#", "#nosuchpane", '#a"]b']) {
+    assert.deepStrictEqual(run(settled(), hash).shown, [], hash);
+}
+// Settings without an active section opens its first one, not OS info
+assert.deepStrictEqual(run(page([link("#osinfo"), link("#vncsettings")]), "").shown, ["#vncsettings"]);
+// OS info as the only section is selected and loaded
+assert.deepStrictEqual(run(page([link("#osinfo")]), ""), {shown: ["#osinfo"], loaded: 1});
+// a redirect to OS info loads it
+assert.deepStrictEqual(run(settled(), "#osinfo"), {shown: ["#settings", "#osinfo"], loaded: 1});
+console.log("ok");

webvirtcloud/test_instance_tabs_js.py

@@ -0,0 +1,23 @@
+"""The VM page opens the tab a redirect points to (static/js/instance_tabs.js).
+Its behaviour is checked with Node."""
+
+import shutil
+import subprocess
+import unittest
+from pathlib import Path
+
+from django.conf import settings
+
+BASE = Path(settings.BASE_DIR)
+
+
+class InstanceTabsTestCase(unittest.TestCase):
+    @unittest.skipUnless(shutil.which("node"), "node is not installed")
+    def test_instance_tabs_js(self):
+        result = subprocess.run(
+            ["node", str(BASE / "webvirtcloud/js_tests/instance_tabs.test.js"), str(BASE / "static/js/instance_tabs.js")],
+            capture_output=True,
+            text=True,
+            timeout=60,
+        )
+        self.assertEqual(result.returncode, 0, result.stderr)