test(file-utils): add unit tests for file operations

Solution-ID: SOL-1735386000002

Issue-ID: ISS-1766921318981-16

Task-ID: T3

ccw/tests/file-utils.test.ts

@@ -0,0 +1,115 @@
+/**
+ * Unit tests for file-utils utility module.
+ *
+ * Notes:
+ * - Targets the runtime implementation shipped in `ccw/dist`.
+ * - Uses in-memory fs stubs (no real file IO).
+ */
+
+import { after, beforeEach, describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+import path from 'node:path';
+import { createRequire } from 'node:module';
+
+const require = createRequire(import.meta.url);
+// eslint-disable-next-line @typescript-eslint/no-var-requires
+const fs = require('node:fs') as typeof import('node:fs');
+
+type FsState = {
+  existing: Set<string>;
+  files: Map<string, string>;
+  writeCalls: Array<{ path: string; content: string; encoding: string }>;
+};
+
+const state: FsState = {
+  existing: new Set(),
+  files: new Map(),
+  writeCalls: [],
+};
+
+function key(filePath: string): string {
+  return path.resolve(filePath).replace(/\\/g, '/').toLowerCase();
+}
+
+function setFile(filePath: string, content: string): void {
+  state.existing.add(key(filePath));
+  state.files.set(key(filePath), content);
+}
+
+const originalFs = {
+  existsSync: fs.existsSync,
+  readFileSync: fs.readFileSync,
+  writeFileSync: fs.writeFileSync,
+};
+
+fs.existsSync = ((filePath: string) => state.existing.has(key(filePath))) as any;
+fs.readFileSync = ((filePath: string, encoding: string) => {
+  assert.equal(encoding, 'utf8');
+  const content = state.files.get(key(filePath));
+  if (content === undefined) {
+    throw new Error(`ENOENT: no such file or directory, open '${filePath}'`);
+  }
+  return content;
+}) as any;
+fs.writeFileSync = ((filePath: string, content: string, encoding: string) => {
+  state.writeCalls.push({ path: filePath, content: String(content), encoding: String(encoding) });
+  setFile(filePath, String(content));
+}) as any;
+
+const fileUtilsUrl = new URL('../dist/utils/file-utils.js', import.meta.url).href;
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+let mod: any;
+
+beforeEach(() => {
+  state.existing.clear();
+  state.files.clear();
+  state.writeCalls.length = 0;
+});
+
+describe('file-utils utility module', async () => {
+  mod = await import(fileUtilsUrl);
+
+  it('readJsonFile parses valid JSON and returns null on failures', () => {
+    const jsonPath = 'C:\\tmp\\data.json';
+    setFile(jsonPath, JSON.stringify({ ok: true, n: 1 }));
+
+    assert.deepEqual(mod.readJsonFile(jsonPath), { ok: true, n: 1 });
+    assert.equal(mod.readJsonFile('C:\\tmp\\missing.json'), null);
+
+    const invalidPath = 'C:\\tmp\\invalid.json';
+    setFile(invalidPath, '{');
+    assert.equal(mod.readJsonFile(invalidPath), null);
+  });
+
+  it('readTextFile reads existing files and returns null when missing', () => {
+    const textPath = 'C:\\tmp\\note.txt';
+    setFile(textPath, 'hello');
+
+    assert.equal(mod.readTextFile(textPath), 'hello');
+    assert.equal(mod.readTextFile('C:\\tmp\\missing.txt'), null);
+  });
+
+  it('writeTextFile writes UTF-8 content', () => {
+    mod.writeTextFile('C:\\tmp\\out.txt', 'content');
+
+    assert.equal(state.writeCalls.length, 1);
+    assert.deepEqual(state.writeCalls[0], {
+      path: 'C:\\tmp\\out.txt',
+      content: 'content',
+      encoding: 'utf8',
+    });
+  });
+
+  it('pathExists delegates to existsSync', () => {
+    assert.equal(mod.pathExists('C:\\tmp\\nope'), false);
+    setFile('C:\\tmp\\yes', '1');
+    assert.equal(mod.pathExists('C:\\tmp\\yes'), true);
+  });
+});
+
+after(() => {
+  fs.existsSync = originalFs.existsSync;
+  fs.readFileSync = originalFs.readFileSync;
+  fs.writeFileSync = originalFs.writeFileSync;
+});
+