refactoring and tests

website/src/test/hooks.mjs

@@ -0,0 +1,27 @@
+// Resolves the virtual modules of SvelteKit to stubs, so that the code that imports them can be
+// tested outside of the framework.
+import { fileURLToPath, pathToFileURL } from 'node:url';
+
+const stubs = {
+    '$app/environment': 'app-environment.ts',
+    '$app/paths': 'app-paths.ts',
+    '$app/state': 'app-state.ts',
+    '$env/static/public': 'env-static-public.ts',
+};
+
+export async function resolve(specifier, context, nextResolve) {
+    const stub = stubs[specifier];
+    if (stub) {
+        const url = pathToFileURL(fileURLToPath(new URL(`./stubs/${stub}`, import.meta.url)));
+        return nextResolve(url.href, context);
+    }
+    return nextResolve(specifier, context);
+}
+
+// Stylesheets are for the browser: importing one gives nothing.
+export async function load(url, context, nextLoad) {
+    if (url.endsWith('.css')) {
+        return { format: 'module', source: '', shortCircuit: true };
+    }
+    return nextLoad(url, context);
+}

website/src/test/register.mjs

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+import { register } from 'node:module';
+
+register('./hooks.mjs', import.meta.url);
+
+// The runes of Svelte are compiled away in the app. In the tests, the modules that use them are
+// only loaded, never relied on for reactivity: a rune is its value.
+globalThis.$state = (value) => value;
+globalThis.$state.raw = (value) => value;
+globalThis.$derived = (value) => value;
+globalThis.$derived.by = (compute) => compute();
+globalThis.$effect = () => {};
+globalThis.$effect.pre = () => {};

website/src/test/stubs/app-environment.ts

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+// The tests run like the browser does, which is where the engine is available.
+export const browser = true;
+export const dev = false;
+export const building = false;
+export const version = 'test';
+
+// what the code that checks `browser` reads of the window
+(globalThis as { window?: unknown }).window ??= { innerWidth: 1280, innerHeight: 800, URL };

website/src/test/stubs/app-paths.ts

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+export const base = '';
+export const assets = '';
+export function resolve(path: string) {
+    return path;
+}

website/src/test/stubs/app-state.ts

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+export const page = { url: new URL('http://localhost/') };
+export const navigating = { from: null, to: null };

website/src/test/stubs/env-static-public.ts

@@ -0,0 +1 @@
+export const PUBLIC_MAPTILER_KEY = 'test-key';