test: add mock DB helper for unit tests

test: add tests for fixtures, mock fetch, mock db, and happy-dom

- Add comprehensive fixture shape tests.
- Expand mockFetch to support methods, status codes, and body tracking.
- Introduce getFetchCalls to inspect intercepted requests.
- Add mockDb helper for in-memory DB operations.
- Reorganize tests for clarity and coverage.
- Ensure happy-dom setup/cleanup works correctly.

tests/helpers/db_mock.ts

@@ -0,0 +1,122 @@
+// Mock de la couche Drizzle pour les tests unitaires/intégration
+// Permet de tester les handlers sans connexion PostgreSQL
+
+export interface MockQueryResult<T> {
+  rows: T[];
+}
+
+export interface MockDbConfig {
+  // Table name → array of rows
+  // deno-lint-ignore no-explicit-any
+  tables: Record<string, Record<string, any>[]>;
+}
+
+/**
+ * Crée un mock de la DB Drizzle.
+ * Simule select/insert/update/delete avec un store en mémoire.
+ *
+ * Usage :
+ * ```ts
+ * const db = createMockDb({
+ *   tables: {
+ *     students: [{ numEtud: 21212006, nom: "Dupont", ... }],
+ *     notes: [],
+ *   }
+ * });
+ *
+ * // Lire toutes les lignes d'une table
+ * const rows = db.getTable("students");
+ *
+ * // Insérer
+ * db.insert("students", { numEtud: 21212009, nom: "Test", ... });
+ *
+ * // Trouver par clé
+ * const student = db.findOne("students", (r) => r.numEtud === 21212006);
+ *
+ * // Supprimer
+ * db.deleteWhere("students", (r) => r.numEtud === 21212006);
+ * ```
+ */
+export function createMockDb(config: MockDbConfig) {
+  // Deep clone pour éviter les mutations entre tests
+  // deno-lint-ignore no-explicit-any
+  const tables: Record<string, Record<string, any>[]> = {};
+  for (const [name, rows] of Object.entries(config.tables)) {
+    tables[name] = rows.map((r) => ({ ...r }));
+  }
+
+  return {
+    /** Retourne toutes les lignes d'une table */
+    getTable<T = Record<string, unknown>>(name: string): T[] {
+      return (tables[name] ?? []) as T[];
+    },
+
+    /** Retourne les lignes qui matchent le filtre */
+    findMany<T = Record<string, unknown>>(
+      name: string,
+      predicate: (row: T) => boolean,
+    ): T[] {
+      return (this.getTable<T>(name)).filter(predicate);
+    },
+
+    /** Retourne la première ligne qui matche, ou undefined */
+    findOne<T = Record<string, unknown>>(
+      name: string,
+      predicate: (row: T) => boolean,
+    ): T | undefined {
+      return (this.getTable<T>(name)).find(predicate);
+    },
+
+    /** Insère une ligne dans la table */
+    insert<T = Record<string, unknown>>(name: string, row: T): T {
+      if (!tables[name]) tables[name] = [];
+      const copy = { ...row } as T;
+      // deno-lint-ignore no-explicit-any
+      tables[name].push(copy as any);
+      return copy;
+    },
+
+    /** Met à jour les lignes qui matchent le prédicat */
+    updateWhere<T = Record<string, unknown>>(
+      name: string,
+      predicate: (row: T) => boolean,
+      updates: Partial<T>,
+    ): number {
+      const rows = this.getTable<T>(name);
+      let count = 0;
+      for (const row of rows) {
+        if (predicate(row)) {
+          Object.assign(row as Record<string, unknown>, updates);
+          count++;
+        }
+      }
+      return count;
+    },
+
+    /** Supprime les lignes qui matchent le prédicat */
+    deleteWhere<T = Record<string, unknown>>(
+      name: string,
+      predicate: (row: T) => boolean,
+    ): number {
+      const before = (tables[name] ?? []).length;
+      tables[name] = (tables[name] ?? []).filter(
+        (r) => !predicate(r as unknown as T),
+      );
+      return before - tables[name].length;
+    },
+
+    /** Vide une table */
+    clear(name: string): void {
+      tables[name] = [];
+    },
+
+    /** Vide toutes les tables */
+    reset(): void {
+      for (const name of Object.keys(tables)) {
+        tables[name] = [];
+      }
+    },
+  };
+}
+
+export type MockDb = ReturnType<typeof createMockDb>;