test: cubrir formatInt/formatDateShort + tooling de cobertura

CLAUDE.md

@@ -56,7 +56,9 @@ implementa ese puerto.
 
 - **Todo el stack**: `docker compose up --build` (desde la raíz).
 - **Tests backend**: `./scripts/test-backend.sh` (dotnet test dockerizado, no requiere SDK local).
+  Cobertura: `dotnet test --collect:"XPlat Code Coverage"` (coverlet, salida Cobertura).
 - **Frontend**: `cd frontend && npm run dev` | `npm run build` | `npm run lint` | `npm run test:run`.
+  Cobertura: `npm run test:coverage` (vitest + v8; informe en `frontend/coverage/`).
 
 ## Gotchas conocidos (transversales)
 

backend/tests/ConnectAnalyzer.Tests/ConnectAnalyzer.Tests.csproj

@@ -15,6 +15,8 @@
     <PackageReference Include="xunit" Version="2.9.2" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2" />
     <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="10.0.0" />
+    <!-- Enables code coverage collection (dotnet test, XPlat Code Coverage / Cobertura). -->
+    <PackageReference Include="coverlet.collector" Version="6.0.2" />
   </ItemGroup>
 
   <ItemGroup>

frontend/app/lib/format.test.ts

@@ -1,5 +1,10 @@
 import { describe, expect, it } from "vitest";
-import { formatAmountCompact, formatAmountFull } from "./format";
+import {
+  formatAmountCompact,
+  formatAmountFull,
+  formatDateShort,
+  formatInt,
+} from "./format";
 
 describe("formatAmountCompact", () => {
   it("collapses thousands into K", () => {
@@ -24,3 +29,20 @@ describe("formatAmountFull", () => {
     expect(formatAmountFull(125.5)).toBe("125.5");
   });
 });
+
+describe("formatInt", () => {
+  it("formats integers with thousands separators and no decimals", () => {
+    expect(formatInt(1_234_567)).toBe("1,234,567");
+    expect(formatInt(42)).toBe("42");
+  });
+});
+
+describe("formatDateShort", () => {
+  it("formats an ISO date as a short month/day label", () => {
+    expect(formatDateShort("2026-01-06")).toBe("Jan 6");
+  });
+
+  it("returns the raw input when it is not a valid Y-M-D date", () => {
+    expect(formatDateShort("not-a-date")).toBe("not-a-date");
+  });
+});

frontend/eslint.config.mjs

@@ -9,6 +9,7 @@ const eslintConfig = defineConfig([
     ".next/**",
     "out/**",
     "build/**",
+    "coverage/**",
     "next-env.d.ts",
   ]),
 ]);