test: add API mock, fixtures, and DOM helpers for tests

tests/helpers/api_mock.ts

@@ -0,0 +1,56 @@
+// Mock de fetch() pour les tests
+
+// deno-lint-ignore no-explicit-any
+let _originalFetch: ((input: any, init?: any) => Promise<Response>) | null =
+  null;
+
+/**
+ * Remplace globalThis.fetch par un mock qui retourne des réponses
+ * pré-configurées selon l'URL.
+ *
+ * @param routes - Map URL pattern → données de réponse (sera sérialisé en JSON)
+ */
+export function mockFetch(
+  routes: Record<string, unknown>,
+): void {
+  _originalFetch = globalThis.fetch;
+
+  globalThis.fetch = (
+    input: string | URL | Request,
+    _init?: RequestInit,
+  ): Promise<Response> => {
+    const url = typeof input === "string"
+      ? input
+      : input instanceof URL
+      ? input.toString()
+      : input.url;
+
+    for (const [pattern, data] of Object.entries(routes)) {
+      if (url.includes(pattern)) {
+        return Promise.resolve(
+          new Response(JSON.stringify(data), {
+            status: 200,
+            headers: { "Content-Type": "application/json" },
+          }),
+        );
+      }
+    }
+
+    return Promise.resolve(
+      new Response(JSON.stringify({ error: "Not Found" }), {
+        status: 404,
+        headers: { "Content-Type": "application/json" },
+      }),
+    );
+  };
+}
+
+/**
+ * Restaure le fetch original.
+ */
+export function restoreFetch(): void {
+  if (_originalFetch) {
+    globalThis.fetch = _originalFetch;
+    _originalFetch = null;
+  }
+}