From e2b2cca1d9cf7304ff0b8c14001378472c92abe9 Mon Sep 17 00:00:00 2001
From: Ajibose <ajiboseibrahim12@gmail.com>
Date: Sun, 30 Aug 2026 19:02:29 +0300
Subject: [PATCH] chore(frontend): consolidate duplicate vitest config files
 (#1281)

Both vitest.config.ts and vitest.config.mts existed simultaneously,
making it unclear which one vitest run actually resolves. Verified
empirically by adding a distinguishing console.error marker to the
top of each config and running `npx vitest run`: only the marker
from vitest.config.ts printed, confirming Vite/Vitest resolves the
.ts file over the .mts one in this repo (Vitest 3.2.7).

This also matches the codebase: setupFiles './src/__tests__/setup.ts'
(referenced by the .ts config) and the actual test layout under
src/__tests__/** and colocated across src/**, both matched by the
.ts config's include pattern. The .mts config's setupFiles pointed
at './src/test-setup.ts', a byte-identical duplicate of the same
setup file, now orphaned and removed.

Kept: vitest.config.ts (happy-dom environment, coverage thresholds,
include pattern, resolve.alias['@']).
Removed: vitest.config.mts (jsdom environment, @vitejs/plugin-react
plugin, no coverage thresholds) and the now-unreferenced
src/test-setup.ts duplicate.

The @vitejs/plugin-react plugin from the removed config was not
carried over: the full test suite (32 files, 286 tests) already
passes without it, since Next.js/Vite's default esbuild JSX
transform handles .tsx test files fine for this project's
happy-dom-based unit tests.

Added a small regression-guard test asserting only one
vitest.config.* file exists in frontend/, so this ambiguity can't
silently reappear.
---
 frontend/src/__tests__/vitest-config.test.ts | 20 +++++++++++++
 frontend/src/test-setup.ts                   | 30 --------------------
 frontend/vitest.config.mts                   | 18 ------------
 3 files changed, 20 insertions(+), 48 deletions(-)
 create mode 100644 frontend/src/__tests__/vitest-config.test.ts
 delete mode 100644 frontend/src/test-setup.ts
 delete mode 100644 frontend/vitest.config.mts

diff --git a/frontend/src/__tests__/vitest-config.test.ts b/frontend/src/__tests__/vitest-config.test.ts
new file mode 100644
index 00000000..30bcd8d5
--- /dev/null
+++ b/frontend/src/__tests__/vitest-config.test.ts
@@ -0,0 +1,20 @@
+import { describe, expect, it } from 'vitest';
+import fs from 'fs';
+import path from 'path';
+
+// Regression guard for https://github.com/LabsCrypt/flowfi/issues/1281:
+// having both vitest.config.ts and vitest.config.mts at the same time makes
+// the resolved test config ambiguous (Vite/Vitest pick one based on
+// extension resolution order, which is not obvious to contributors and can
+// silently disable the "other" config's environment, setup file, and
+// coverage thresholds). Only one vitest.config.* should ever exist.
+describe('vitest config', () => {
+  it('has exactly one vitest.config.* file in the frontend package', () => {
+    const frontendRoot = path.resolve(__dirname, '..', '..');
+    const configFiles = fs
+      .readdirSync(frontendRoot)
+      .filter((f) => /^vitest\.config\.(ts|mts|cts|js|mjs|cjs)$/.test(f));
+
+    expect(configFiles).toEqual(['vitest.config.ts']);
+  });
+});
diff --git a/frontend/src/test-setup.ts b/frontend/src/test-setup.ts
deleted file mode 100644
index 3310558c..00000000
--- a/frontend/src/test-setup.ts
+++ /dev/null
@@ -1,30 +0,0 @@
-import '@testing-library/jest-dom';
-import { vi } from 'vitest';
-
-const localStorageMock = (() => {
-  let store: Record<string, string> = {};
-  return {
-    getItem: vi.fn((key: string) => store[key] || null),
-    setItem: vi.fn((key: string, value: string) => {
-      store[key] = value.toString();
-    }),
-    clear: vi.fn(() => {
-      store = {};
-    }),
-    removeItem: vi.fn((key: string) => {
-      delete store[key];
-    }),
-    key: vi.fn((index: number) => Object.keys(store)[index] || null),
-    length: 0,
-  };
-})();
-
-vi.stubGlobal('localStorage', localStorageMock);
-if (typeof window !== 'undefined') {
-  Object.defineProperty(window, 'localStorage', {
-    value: localStorageMock,
-    configurable: true,
-    writable: true,
-  });
-}
-
diff --git a/frontend/vitest.config.mts b/frontend/vitest.config.mts
deleted file mode 100644
index 1e79ea10..00000000
--- a/frontend/vitest.config.mts
+++ /dev/null
@@ -1,18 +0,0 @@
-import { defineConfig } from 'vitest/config';
-import react from '@vitejs/plugin-react';
-import path from 'path';
-
-export default defineConfig({
-  // @ts-expect-error type mismatch between vite versions in monorepo
-  plugins: [react()],
-  resolve: {
-    alias: {
-      '@': path.resolve(__dirname, './src'),
-    },
-  },
-  test: {
-    environment: 'jsdom',
-    globals: true,
-    setupFiles: ['./src/test-setup.ts'],
-  },
-});