test: add few unit tests

package.json

@@ -75,6 +75,7 @@
     "jest": "^29.7.0",
     "lint-staged": "^14.0.1",
     "prettier": "^3.0.3",
+    "stream-mock": "^2.0.5",
     "ts-jest": "^29.1.1",
     "typescript": "^5.2.2"
   }

src/tasks/create-express-task.ts

@@ -28,7 +28,7 @@ const copyAsync = promisify(ncp);
  * @param {string} projectDescription - The description of the xarvis project.
  * @returns {stream.Transform} A transform stream that replaces placeholders with provided values.
  */
-const transformTemplateWithConfig = (projectName: string, projectDescription: string): stream.Transform => {
+export const transformTemplateWithConfig = (projectName: string, projectDescription: string): stream.Transform => {
   return new stream.Transform({
     transform(chunk, _, callback) {
       let modifiedChunk = chunk.toString('utf8');

tests/tasks/create-express-task.test.ts

@@ -0,0 +1,29 @@
+import { transformTemplateWithConfig } from '../../src/tasks/create-express-task';
+import { ObjectWritableMock } from 'stream-mock';
+
+describe('CreateExpressTask', () => {
+  describe('transformTemplateWithConfig', () => {
+    it('should replace project name and description in the stream', (done) => {
+      const projectName = 'xarvis';
+      const description = 'a CLI tool to generate production ready apps';
+
+      const input = 'Project name: {{project_name}}, and this is {{project_description}}';
+      const expectedOutput = `Project name: ${projectName}, and this is ${description}`;
+
+      const transformStream = transformTemplateWithConfig(projectName, description);
+      const writableStream = new ObjectWritableMock();
+
+      transformStream.write(input, 'utf-8', () => {
+        transformStream.end();
+      });
+
+      transformStream.pipe(writableStream);
+
+      writableStream.on('finish', () => {
+        const transformedData = writableStream.data.toString();
+        expect(transformedData).toEqual(expectedOutput);
+        done();
+      });
+    });
+  });
+});