tested utils checkImageFormatValidity

tests/helpers/utils.test.js

@@ -1,15 +1,63 @@
 const {enums} = require("../../src/enums");
 
-const fetchMock = require('jest-fetch-mock');
-fetchMock.enableMocks();
-
 const {utils} = require("../../src/helpers/utils.js");
 
 describe('utils', () => {
 
+    const attachmentUrl = 'oya.png';
+    let blob;
+
     beforeEach(() => {
         jest.resetModules();
         jest.clearAllMocks();
+        blob = new Blob([JSON.stringify({attachmentUrl: attachmentUrl})], {type: 'image/png'});
+        global.fetch = jest.fn(() =>
+            Promise.resolve({
+                blob: () => Promise.resolve(blob),
+            })
+        );
+
+    })
+
+    describe('checkImageFormatValidity', () => {
+
+        test('calls fetch with imageUrl and returns true if no errors', async() => {
+            // Act
+            const res = await utils.checkImageFormatValidity(attachmentUrl);
+            // Assert
+            expect(res).toBe(true);
+            expect(fetch).toHaveBeenCalledTimes(1);
+            expect(fetch).toHaveBeenCalledWith(attachmentUrl);
+        })
+
+        test('throws error if fetch returns error', async() => {
+            // Arrange
+            global.fetch = jest.fn().mockImplementation(() =>{throw Error('error');});
+            // Act & Assert
+            await expect(utils.checkImageFormatValidity(attachmentUrl)).rejects.toThrow(`${enums.err.PROPIC_CANNOT_LOAD}: error`);
+        })
+
+        test('throws error if blob returns error', async() => {
+            // Arrange
+            global.fetch = jest.fn(() =>
+                Promise.resolve({
+                    blob: () => Promise.reject(new Error('error'))
+                }))
+            // Act & Assert
+            await expect(utils.checkImageFormatValidity(attachmentUrl)).rejects.toThrow('error');
+        })
+
+        test('throws error if blob in wrong format', async() => {
+            // Arrange
+            blob =  new Blob([JSON.stringify({attachmentUrl})], {type: 'text/html'});
+            global.fetch = jest.fn(() =>
+                Promise.resolve({
+                    blob: () => Promise.resolve(blob),
+                })
+            );
+            // Act & Assert
+            await expect(utils.checkImageFormatValidity(attachmentUrl)).rejects.toThrow(enums.err.PROPIC_FAILS_REQUIREMENTS);
+        })
     })
 
     afterEach(() => {