test:set up initial structure for unit tests for fetchCalendarData function

package.json

@@ -23,6 +23,7 @@
   "devDependencies": {
     "@babel/preset-env": "^7.26.0",
     "@babel/register": "^7.25.9",
-    "jest": "^29.7.0"
+    "jest": "^29.7.0",
+    "rewire": "^7.0.0"
   }
 }

test/calendarUtil.test.js

@@ -0,0 +1,51 @@
+import fs from 'fs'; 
+import axios from 'axios';
+
+// Describe the test suite for Calendar Utility Functions
+describe('Calendar Utility Functions', () => {
+  // Declare variable to hold the functions we will be testing
+  let fetchCalendarData;
+
+  beforeAll(async () => {
+    const calendarUtilModule = await import('../src/calendarUtil.js');
+    fetchCalendarData = calendarUtilModule.fetchCalendarData;
+  });
+
+  // Describe a nested test suite for the 'fetchCalendarData' function
+  describe('fetchCalendarData', () => {
+    
+    // Test case: fetching data from a URL
+    it('fetches data from a URL', async () => {
+      const testCalendar = { url: 'https://calendar.google.com/calendar/ical/b4c66eb4bb2cc15257d071bab3f935385778b042112ea1aaedada47f3f1a6e3a%40group.calendar.google.com/public/basic.ics' };
+
+      // Mock the axios.get method to resolve with specific test data
+      jest.spyOn(axios, 'get').mockResolvedValue({ data: 'test data' });
+
+      // Call the fetchCalendarData function with the test calendar object
+      const result = await fetchCalendarData(testCalendar);
+
+      // Assert that the fetched result's data matches the expected test data
+      expect(result.data).toBe('test data');
+
+      // Restore the original axios.get method after the test
+      axios.get.mockRestore();
+    });
+
+    // Test case: reading data from a file
+    it('reads data from a file', async () => {
+      const testCalendar = { url: './test_calendars/work_task_calendar.ics' };
+
+      // Mock the fs.readFileSync method to return specific test data
+      jest.spyOn(fs, 'readFileSync').mockReturnValue('file data');
+
+      // Call the fetchCalendarData function with the test calendar object
+      const result = await fetchCalendarData(testCalendar);
+
+      // Assert that the fetched result's data matches the expected file data
+      expect(result.data).toBe('file data');
+
+      // Restore the original fs.readFileSync method after the test
+      fs.readFileSync.mockRestore();
+    });
+  });
+});