Add tests and error handling for writeImageFile

Added try/catch error handling to writeImageFile in src/storage.ts
and created comprehensive test coverage in src/storage.test.ts.

Co-authored-by: Horizontal42 <75383519+Horizontal42@users.noreply.github.com>

src/storage.test.ts

@@ -1,6 +1,6 @@
 import { logger } from "./logger";
 import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
-import { isTauri, loadSettings, saveSettings, defaultSettingsData, loadAppData, saveAppData, flushAppData, setDataDir, runBackups, backupDeletedSheet, openBackupsFolder, chooseFolder, dataDirHasDocuments, migrateDataDir, fetchRates, fetchHistoricalRates } from './storage';
+import { isTauri, loadSettings, saveSettings, defaultSettingsData, loadAppData, saveAppData, flushAppData, setDataDir, runBackups, backupDeletedSheet, openBackupsFolder, chooseFolder, dataDirHasDocuments, migrateDataDir, fetchRates, fetchHistoricalRates, writeImageFile } from './storage';
 import { invoke } from '@tauri-apps/api/core';
 
 vi.mock('@tauri-apps/api/core', () => ({
@@ -382,6 +382,30 @@ describe('storage', () => {
     });
   });
 
+  describe('writeImageFile', () => {
+    it('returns false when not in Tauri', async () => {
+      const result = await writeImageFile('base64data');
+      expect(invoke).not.toHaveBeenCalled();
+      expect(result).toBe(false);
+    });
+
+    it('returns true when in Tauri and invoke succeeds', async () => {
+      vi.stubGlobal('window', { __TAURI_INTERNALS__: {} });
+      vi.mocked(invoke).mockResolvedValue(true);
+      const result = await writeImageFile('base64data');
+      expect(invoke).toHaveBeenCalledWith('write_image_file', { dataBase64: 'base64data' });
+      expect(result).toBe(true);
+    });
+
+    it('returns false and logs warning if invoke fails', async () => {
+      vi.stubGlobal('window', { __TAURI_INTERNALS__: {} });
+      vi.mocked(invoke).mockRejectedValue(new Error('invoke error'));
+      const result = await writeImageFile('base64data');
+      expect(logger.warn).toHaveBeenCalledWith('writeImageFile failed', expect.any(Error));
+      expect(result).toBe(false);
+    });
+  });
+
   describe('fetchHistoricalRates', () => {
     it('uses invoke when in Tauri', async () => {
       vi.stubGlobal('window', { __TAURI_INTERNALS__: {} });

src/storage.ts

@@ -256,7 +256,12 @@ export async function fetchHistoricalRates(date: string): Promise<Record<string,
 
 export async function writeImageFile(dataBase64: string): Promise<boolean> {
   if (!isTauri()) return false;
-  return invoke("write_image_file", { dataBase64 });
+  try {
+    return await invoke("write_image_file", { dataBase64 });
+  } catch (e) {
+    logger.warn("writeImageFile failed", e);
+    return false;
+  }
 }
 
 // ---------- market data