how to generate custom report in selenium

As part of an experiment, I implemented a custom test reporting mechanism similar to ExtentReports.

• I used TestNG listeners (ITestListener) to capture test execution events.
• Each test result—success, failure, or skipped—is recorded in a List<Map<String, String>> results.
• The listener methods onTestSuccess, onTestFailure, and onTestSkipped add entries for each test case to this list.
• After the entire test suite finishes, the onFinish method is invoked automatically by TestNG.
• In onFinish, the accumulated results are written into a JSON report file (test-results.json) using Java’s FileWriter.
• This JSON can later be used to generate HTML reports or for further visualization (charts, dashboards, etc.).

This approach allows you to have a lightweight, flexible, and customizable reporting solution without relying on external reporting libraries.

Example: JsonReporter Class in Java

import org.testng.ITestContext;
import org.testng.ITestListener;
import org.testng.ITestResult;

import java.io.FileWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class JsonReporter implements ITestListener {

private final List<Map<String, String>> results = new ArrayList<>();

// Called when a test passes
@Override
public void onTestSuccess(ITestResult result) {
    recordResult(result, "PASS", null);
}

// Called when a test fails
@Override
public void onTestFailure(ITestResult result) {
    recordResult(result, "FAIL", result.getThrowable() != null ? result.getThrowable().toString() : "");
}

// Called when a test is skipped
@Override
public void onTestSkipped(ITestResult result) {
    recordResult(result, "SKIPPED", null);
}

// Helper method to record test result in the results list
private void recordResult(ITestResult result, String status, String error) {
    Map<String, String> entry = new HashMap<>();
    entry.put("testName", result.getName());
    entry.put("status", status);
    if (error != null) entry.put("error", error);
    results.add(entry);
}

// Called once after all tests in the suite have finished
@Override
public void onFinish(ITestContext context) {
    StringBuilder json = new StringBuilder("[\n");
    for (int i = 0; i < results.size(); i++) {
        Map<String, String> entry = results.get(i);
        json.append("  {\n");
        json.append("    \"testName\": \"").append(entry.get("testName")).append("\",\n");
        json.append("    \"status\": \"").append(entry.get("status")).append("\"");
        if (entry.containsKey("error")) {
            json.append(",\n    \"error\": \"").append(entry.get("error")).append("\"");
        }
        json.append("\n  }");
        if (i < results.size() - 1) json.append(",");
        json.append("\n");
    }
    json.append("]\n");

    try (FileWriter writer = new FileWriter("test-output/test-results.json")) {
        writer.write(json.toString());
        System.out.println("Results written to test-output/test-results.json");
    } catch (Exception e) {
        e.printStackTrace();
    }
}

// Optional overrides (not required)
@Override public void onTestStart(ITestResult result) {}
@Override public void onStart(ITestContext context) {}

}

Add Listerner TestNG Suite file:

<?xml version=”1.0″ encoding=”UTF-8″?>

<!DOCTYPE suite SYSTEM “https://testng.org/testng-1.0.dtd”>

<suite name=”Suite”>

<listeners>

<listener class-name=”tests.JsonReporter”/>

</listeners>

<test thread-count=”5″ name=”Test”>

<classes>

<class name=”tests.LoginTest” />

<class name=”tests.SampleTest” />

</classes>

</test> <!– Test –>

</suite> <!– Suite –>

Once the JSON report (test-results.json) is generated, we can open reports.html to display the test results in a readable format.

• The HTML page reads test-results.json using the fetch() method.
• The test results are inserted row by row into a table with the ID resultsTable.
• For better readability, the report also includes a pie chart that visualizes the distribution of PASS and FAIL tests.
  • Green is used to represent passed tests.
  • Red is used to represent failed tests.
• Display Reports Locally: Hosting HTML and JSON Files on Localhost (Required for Fetch to Read Files)

This approach allows a quick visual summary of test outcomes while maintaining a detailed tabular report for individual test cases.

HTML example with JavaScript

<!DOCTYPE html>

<html>

<head>

  <title>Test Dashboard</title>

  <script src=”https://cdn.jsdelivr.net/npm/chart.js”></script>

</head>

<body>

  <h2>Selenium Test Results</h2>

  <table border=”1″ id=”resultsTable”>

    <tr><th>Test Name</th><th>Status</th><th>Error</th></tr>

  </table>

  <canvas id=”statusChart” width=”100″ height=”100″></canvas>

  <script>

    fetch(‘test-results.json’)

      .then(res => res.json())

      .then(data => {

        let pass = 0, fail = 0;

        const table = document.getElementById(‘resultsTable’);

        data.forEach(t => {

          const row = table.insertRow();

          row.insertCell(0).innerText = t.testName;

          row.insertCell(1).innerText = t.status;

          row.insertCell(2).innerText = t.error || ”;

          if(t.status === ‘PASS’) pass++; else fail++;

        });

        // Chart

        new Chart(document.getElementById(‘statusChart’), {

          type: ‘pie’,

          data: {

            labels: [‘PASS’, ‘FAIL’],

            datasets: [{

              data: [pass, fail],

              backgroundColor: [‘green’, ‘red’]

            }]

          }

        });

      });

  </script>

</body>

</html>