CSV data reading in Selenium Java - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Reading CSV file with BufferedReader

What will be the output of this Selenium Java code snippet that reads a CSV file line by line and prints each line?

Selenium Java

import java.io.*;

public class CsvReader {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new FileReader("data.csv"));
        String line;
        while ((line = br.readLine()) != null) {
            System.out.println(line);
        }
        br.close();
    }
}

// Assume data.csv content:
// name,age,city
// Alice,30,New York
// Bob,25,Los Angeles

A

name,age,city
Alice,30,New York
Bob,25,Los Angeles

B

name;age;city
Alice;30;New York
Bob;25;Los Angeles

C

name|age|city
Alice|30|New York
Bob|25|Los Angeles

D SyntaxError at line 4

💡 Hint

Look carefully at how BufferedReader reads lines and prints them exactly as in the file.

BufferedReader reads each line as a string and prints it exactly. Since the CSV uses commas, the output lines contain commas.

❓ assertion

intermediate

Validating CSV data read into a list

Given this code snippet that reads CSV data into a List in Selenium Java, which assertion correctly verifies the second row's first column is 'Alice'?

Selenium Java

import java.io.*;
import java.util.*;

public class CsvData {
    public static List<String[]> readCsv(String filePath) throws IOException {
        List<String[]> data = new ArrayList<>();
        BufferedReader br = new BufferedReader(new FileReader(filePath));
        String line;
        while ((line = br.readLine()) != null) {
            data.add(line.split(","));
        }
        br.close();
        return data;
    }
}

A assertFalse(data.get(1)[1].equals("Alice"));

B assertEquals("Alice", data.get(0)[1]);

C assertTrue(data.get(2)[0].equals("Alice"));

D assertEquals("Alice", data.get(1)[0]);

💡 Hint

Remember that list index 0 is the header row.

The first row (index 0) is the header, so the second row (index 1) contains 'Alice' in the first column (index 0).

🔧 Debug

advanced

Fixing CSV file path error in Selenium Java test

This Selenium Java code throws a FileNotFoundException when trying to read 'data.csv'. What is the most likely cause?

Selenium Java

BufferedReader br = new BufferedReader(new FileReader("data.csv"));
String line = br.readLine();
br.close();

A The BufferedReader class is not imported.

B The file 'data.csv' is not in the project root or working directory.

C The file 'data.csv' is empty.

D The FileReader constructor requires an absolute path.

💡 Hint

Check where the program looks for the file relative to the running location.

FileNotFoundException usually means the file path is incorrect or the file is missing in the expected directory.

❓ framework

advanced

Best practice for CSV data-driven tests in Selenium Java

Which approach is best to integrate CSV data reading into Selenium Java tests for multiple test cases?

A Use a TestNG DataProvider method that reads CSV and supplies data arrays to test methods.

B Manually read CSV inside each test method before assertions.

C Hardcode CSV data inside test methods as string arrays.

D Use Selenium WebDriver to open CSV files in browser and read data.

💡 Hint

Think about reusability and separation of test data from test logic.

TestNG DataProvider allows clean, reusable data-driven tests by reading CSV once and feeding data to multiple tests.

🧠 Conceptual

expert

Handling special characters in CSV data reading

When reading CSV files with Selenium Java tests, which issue can arise if the CSV contains commas inside quoted fields, and how to handle it?

A Use String.split(",") and then trim quotes manually to fix fields.

B Commas inside quotes are ignored automatically by BufferedReader; no special handling needed.

C Splitting lines by comma directly breaks fields with commas inside quotes; use a CSV parsing library like OpenCSV to handle quoted fields correctly.

D Replace all commas with semicolons before reading to avoid issues.

💡 Hint

Think about how simple split by comma treats commas inside quotes.

Simple split by comma fails on quoted fields containing commas. Libraries like OpenCSV parse CSV correctly respecting quotes.

Practice

1. What is the main benefit of reading test data from a CSV file in Selenium Java tests?

easy

A. It automatically generates test reports.

B. It makes the test run faster by skipping validations.

C. It allows running the same test with multiple data sets easily.

D. It replaces the need for writing test scripts.

Solution

1. Step 1: Understand the purpose of CSV data reading

   CSV files store multiple sets of data externally, allowing tests to use different inputs without changing code.

2. Step 2: Identify the benefit in test execution

   Using CSV data lets the same test run repeatedly with different inputs, improving coverage and maintenance.

3. Final Answer:

   It allows running the same test with multiple data sets easily. -> Option C

4. Quick Check:

   CSV data = multiple test inputs [OK]

Hint: CSV files separate data from code for easy test reuse [OK]

Common Mistakes:

• Thinking CSV speeds up test execution
• Believing CSV auto-generates reports
• Assuming CSV replaces test scripts

2. Which of the following Java code snippets correctly reads a CSV file line by line using BufferedReader?

easy

A. BufferedReader br = new BufferedReader(new FileReader("data.csv")); String line = br.readLine(); while (line != null) { System.out.println(line); } br.close();

B. BufferedReader br = new BufferedReader(new FileReader("data.csv")); String line; while ((line = br.readLine()) != null) { System.out.println(line); } br.close();

C. BufferedReader br = new BufferedReader(new FileReader("data.csv")); while (br.readLine() != null) { System.out.println(line); } br.close();

D. BufferedReader br = new BufferedReader(new FileReader("data.csv")); for (int i=0; i<10; i++) { System.out.println(br.readLine()); } br.close();

Solution

1. Step 1: Check correct BufferedReader usage

   BufferedReader br = new BufferedReader(new FileReader("data.csv")); String line; while ((line = br.readLine()) != null) { System.out.println(line); } br.close(); correctly initializes BufferedReader, reads each line into 'line', checks for null, and prints it inside the loop.

2. Step 2: Identify errors in other options

   BufferedReader br = new BufferedReader(new FileReader("data.csv")); while (br.readLine() != null) { System.out.println(line); } br.close(); uses 'line' without assignment; BufferedReader br = new BufferedReader(new FileReader("data.csv")); String line = br.readLine(); while (line != null) { System.out.println(line); } br.close(); never updates 'line' inside loop; BufferedReader br = new BufferedReader(new FileReader("data.csv")); for (int i=0; i<10; i++) { System.out.println(br.readLine()); } br.close(); reads fixed 10 lines without null check.

3. Final Answer:

   BufferedReader br = new BufferedReader(new FileReader("data.csv")); String line; while ((line = br.readLine()) != null) { System.out.println(line); } br.close(); -> Option B

4. Quick Check:

   Assign line inside while condition [OK]

Hint: Assign line inside while condition to avoid null errors [OK]

Common Mistakes:

• Not assigning line inside the loop condition
• Forgetting to update line inside the loop
• Not checking for null before printing

3. Given the following code snippet, what will be the output if the CSV file contains:
name,age John,30 Jane,25

BufferedReader br = new BufferedReader(new FileReader("data.csv")); String line; while ((line = br.readLine()) != null) { String[] data = line.split(","); System.out.println(data[0] + " is " + data[1] + " years old."); } br.close();

medium

A. name is age years old.
John is 30 years old.
Jane is 25 years old.

B. John is 30 years old.
Jane is 25 years old.

C. name,age
John,30
Jane,25

D. Error: ArrayIndexOutOfBoundsException

Solution

1. Step 1: Understand CSV content and reading loop

   The CSV has a header line 'name,age' and two data lines. The code reads each line and splits by comma.

2. Step 2: Analyze output for each line

   For the header line, data[0] = 'name', data[1] = 'age', so prints 'name is age years old.' Then for John and Jane lines, prints their names and ages accordingly.

3. Final Answer:

   name is age years old. John is 30 years old. Jane is 25 years old. -> Option A

4. Quick Check:

   Header line included in output [OK]

Hint: CSV header line is read like data unless skipped [OK]

Common Mistakes:

• Assuming header line is skipped automatically
• Expecting only data lines output
• Ignoring split results causing errors

4. Identify the error in this CSV reading code snippet:

BufferedReader br = new BufferedReader(new FileReader("data.csv"));
String line = br.readLine();
while (line != null) {
  String[] values = line.split(",");
  System.out.println(values[0]);
}

medium

A. The code is correct and will print the first column.

B. The split method is used incorrectly; it should be split(';').

C. BufferedReader should be replaced with Scanner for CSV files.

D. The loop never updates 'line', causing an infinite loop.

Solution

1. Step 1: Review loop condition and update

   The variable 'line' is assigned once before the loop but never updated inside the loop, so the condition never changes.

2. Step 2: Consequence of missing update

   Without updating 'line' inside the loop, it causes an infinite loop printing the first line repeatedly.

3. Final Answer:

   The loop never updates 'line', causing an infinite loop. -> Option D

4. Quick Check:

   Update line inside loop to avoid infinite loop [OK]

Hint: Always update loop variable inside while to avoid infinite loops [OK]

Common Mistakes:

• Forgetting to update 'line' inside the loop
• Confusing split delimiter with semicolon
• Thinking Scanner is mandatory for CSV

5. You want to read a CSV file with test data and run a Selenium test for each row. Which approach correctly integrates CSV reading with a test method in Java?

hard

A. Read the CSV in a separate method that returns a List; then loop over this list in the test method to run tests with each data set.

B. Hardcode all test data inside the test method and ignore CSV files.

C. Read the CSV file inside the test method but do not loop; only use the first line.

D. Use BufferedReader to read CSV but do not close it after reading.

Solution

1. Step 1: Separate data reading from test logic

   Reading CSV in a separate method improves code reuse and clarity by returning all data as a list.

2. Step 2: Loop over data in test method

   The test method loops over the list of data arrays, running the test for each data set, enabling data-driven testing.

3. Final Answer:

   Read the CSV in a separate method that returns a List; then loop over this list in the test method to run tests with each data set. -> Option A

4. Quick Check:

   Separate data reading and loop in test [OK]

Hint: Separate CSV reading method returns data list for test loops [OK]

Common Mistakes:

• Hardcoding data inside tests reduces flexibility
• Using only first CSV line ignores other data
• Not closing BufferedReader causes resource leaks