XLSX File Uploads in Cypress

XLSX File Uploads in Cypress: A Comprehensive Guide

As QA automation engineers, we often rely on fixtures to manage test data in Cypress. However, there are times when fixtures aren't enough, especially when dealing with file uploads. In my experience, interacting with XLSX files can present unique challenges, particularly when the application requires dynamic, rather than static, file uploads. While resources exist online, they often provide fragmented information, making it difficult to piece together a complete solution.

This blog post aims to consolidate that scattered knowledge into a single, comprehensive guide. If you're looking to add robust XLSX file upload testing to your Cypress test suite, this post will provide you with a step-by-step approach, complete with code examples and explanations.

The Challenge: Dynamic XLSX File Generation

While Cypress provides the cy.writeFile command for file creation, it falls short when it comes to generating functional XLSX files. Attempting to create an XLSX file using cy.writeFile results in a file that either fails to open or is recognized as an unsupported/corrupted format. This is because the command doesn't write the file in the correct binary format required for XLSX files.

The Solution: Leveraging Node.js and the XLSX Library

To overcome this limitation, we can harness the power of Node.js and the xlsx library. This library allows us to create XLSX files programmatically in the correct format.

Step 1: Installing the XLSX Package

First, let's install the xlsx package using npm:

npm install xlsx

Step 2: Configuring Cypress to Use the XLSX Library

Next, we need to configure Cypress to use the xlsx library by adding a task to our cypress.config.js (or plugins/index.js) file. This task will handle the XLSX file creation process.

// cypress.config.js (or plugins/index.js)
const xlsx = require('xlsx');
module.exports = {
  e2e: {
    setupNodeEvents(on, config) {
      on('task', {
        writeXLSX({ filePath, data, sheetName = 'Sheet1' }) {
          const ws = xlsx.utils.json_to_sheet(data);
          const wb = xlsx.utils.book_new();
          xlsx.utils.book_append_sheet(wb, ws, sheetName);
          xlsx.writeFile(wb, filePath);
          return null; // Tasks must return a value or a Promise
        },
      });
      return config;
    },
  },
};

Explanation:

We require the xlsx library.
We define a task called writeXLSX that accepts the file path, data, and sheet name as arguments.
Inside the task, we use the xlsx library to convert the data (in JSON format) to a worksheet, create a workbook, append the worksheet to the workbook, and then write the workbook to the specified file path.

Step 3: Creating a Cypress Test to Generate and Upload the XLSX File

Now that we have configured Cypress to use the xlsx library, we can create a test to generate and upload the XLSX file.

describe('XLSX Creation and Upload Test', () => {
  it('should write data to an XLSX file and upload it', () => {
    const testData = [
      { Name: 'John Doe', Age: 30, City: 'New York' },
      { Name: 'Jane Smith', Age: 25, City: 'London' },
    ];
    const filePath = 'cypress/fixtures/output.xlsx';
    cy.task('writeXLSX', { filePath, data: testData }).then(() => {
      cy.log('XLSX file written successfully!');
      cy.get('[type="file"]').selectFile(filePath, { force: true });
    });
  });
});

Explanation:

We define an array of objects (testData) representing the data we want to write to the XLSX file. Each object represents a row in the spreadsheet.
We define the file path where we want to save the XLSX file.
We use the cy.task command to call the writeXLSX task we defined in the cypress.config.js file.
Once the task completes, we use the cy.get command to locate the file input element on the page (identified by the type="file" attribute) and then use the cy.selectFile command to select the generated XLSX file. The { force: true } option is used to bypass any visibility checks.

Understanding cy.selectFile

The cy.selectFile command is a powerful tool for simulating file uploads in Cypress. It allows us to select a file from our system and upload it to the HTML input element, effectively simulating the user dragging the file into the browser. This eliminates the need to interact with the "Browse" button and the file search modal, making our tests more robust and easier to maintain.

Additional Resources:

Cypress writeFile Command: https://docs.cypress.io/api/commands/writefile
Cypress selectFile Command: https://docs.cypress.io/api/commands/selectfile
XLSX Library: https://www.npmjs.com/package/xlsx

Conclusion:

This guide provides a clear and concise approach to handling XLSX file uploads in Cypress. By combining the power of Node.js, the xlsx library, and Cypress commands like cy.task and cy.selectFile, you can create robust and reliable tests that accurately simulate user interactions with file uploads. I hope this guide helps you streamline your Cypress testing process and confidently tackle XLSX file uploads in your applications.

Happy testing!