test(services): add tests for service layer functions

test/services/saveImageToFile.test.js

@@ -0,0 +1,72 @@
+import { expect } from 'chai';
+import sinon from 'sinon';
+import esmock from 'esmock';
+import path from 'path';
+
+describe('saveImageToFile', function() {
+  let downloadImageStub;
+  let ensureDirectoryExistsStub;
+  let saveImageToFile;
+
+  const imageUrl = 'http://example.com/image.jpg';
+  const outputDirectory = 'path/to/output';
+  const savedImagePath = path.join(path.resolve(outputDirectory), path.basename(imageUrl));
+
+  beforeEach(async function() {
+    downloadImageStub = sinon.stub().resolves(savedImagePath);
+    ensureDirectoryExistsStub = sinon.stub();
+
+    // Mocking downloadImage and ensureDirectoryExists functions
+    saveImageToFile = await esmock('../../src/services/saveImageToFile.js', {
+      '../../src/utils/downloadImage.js': { default: downloadImageStub },
+      '../../src/utils/ensureDirectoryExists.js': { default: ensureDirectoryExistsStub }
+    });
+
+    saveImageToFile = saveImageToFile.default;
+  });
+
+  afterEach(() => {
+    sinon.restore();
+    esmock.purge();
+  });
+
+  it('should save image to specified directory', async function() {
+    const result = await saveImageToFile(imageUrl, outputDirectory);
+
+    // Ensure ensureDirectoryExists is called with the resolved output directory
+    expect(ensureDirectoryExistsStub.calledOnceWithExactly(path.resolve(outputDirectory))).to.be.true;
+
+    // Ensure downloadImage is called with correct URL and save path
+    expect(downloadImageStub.calledOnceWithExactly(imageUrl, savedImagePath)).to.be.true;
+
+    // Validate the return value (saved image path)
+    expect(result).to.equal(savedImagePath);
+  });
+
+  it('should throw an error if downloadImage fails', async function() {
+    const error = new Error('Failed to download image');
+    downloadImageStub.rejects(error);
+
+    try {
+      await saveImageToFile(imageUrl, outputDirectory);
+      expect.fail('Expected an error to be thrown');
+    } catch (err) {
+      // Ensure error is logged and re-thrown
+      expect(err).to.equal(error);
+    }
+  });
+
+  it('should throw an error if ensureDirectoryExists fails', async function() {
+    const error = new Error('Failed to ensure directory exists');
+    ensureDirectoryExistsStub.throws(error);
+
+    try {
+      await saveImageToFile(imageUrl, outputDirectory);
+      expect.fail('Expected an error to be thrown');
+    } catch (err) {
+      // Ensure error is logged and re-thrown
+      expect(err).to.equal(error);
+    }
+  });
+});
+