pytest-html for HTML reports - Build an Automation Script

Generate HTML report using pytest-html plugin

Preconditions (2)

Step 1: Run pytest command with --html=report.html option

Step 2: Wait for tests to complete

Step 3: Open the generated report.html file in a browser

✅ Expected Result: The HTML report file is created with test results summary and details visible in the browser

Automation Requirements - pytest

Assertions Needed:

Verify the pytest command runs successfully

Verify the report.html file is created

Verify the report.html file contains the test name and pass/fail status

Best Practices:

Use pytest fixtures for setup and teardown if needed

Use subprocess module to run pytest command in automation script

Check file existence and content with assertions

Automated Solution

PyTest

import subprocess
import os
import re

def test_generate_html_report():
    # Run pytest with html report option
    result = subprocess.run(['pytest', '--html=report.html', '--self-contained-html'], capture_output=True, text=True)
    
    # Assert pytest ran successfully
    assert result.returncode == 0, f"Pytest failed with output:\n{result.stdout}\n{result.stderr}"

    # Assert report.html file exists
    assert os.path.exists('report.html'), "HTML report file was not created"

    # Read report content
    with open('report.html', 'r', encoding='utf-8') as f:
        content = f.read()

    # Check that test function name appears in report
    assert re.search(r'test_generate_html_report', content), "Test name not found in HTML report"

    # Check that status 'passed' or 'failed' appears
    assert re.search(r'passed|failed', content, re.IGNORECASE), "Test status not found in HTML report"

This script runs pytest with the --html=report.html option to generate an HTML report.

We use subprocess.run to execute the pytest command and capture its output and return code.

We assert that pytest finishes successfully by checking returncode == 0.

Then we check if the report.html file was created.

Finally, we open the report file and verify it contains the test function name and a test status like 'passed' or 'failed'.

This ensures the HTML report was generated correctly and includes test results.

Common Mistakes - 4 Pitfalls

{'mistake': 'Not installing pytest-html plugin before running tests', 'why_bad': 'The pytest command will fail or ignore the --html option, so no report is generated.', 'correct_approach': "Install pytest-html using 'pip install pytest-html' before running tests."}

{'mistake': 'Running pytest without capturing output or checking return code', 'why_bad': "You won't know if pytest failed or passed, making the automation unreliable.", 'correct_approach': 'Use subprocess.run with capture_output=True and check returncode to verify pytest success.'}

Checking for report file existence without verifying content

Hardcoding file paths without considering working directory

Bonus Challenge

Now add data-driven testing with 3 different simple test functions and generate a combined HTML report

Show Hint

Practice

1. What is the main purpose of using pytest-html in testing?

easy

A. To run tests faster than usual

B. To convert Python code into HTML

C. To write tests in HTML format

D. To generate easy-to-read HTML reports of test results

Solution

1. Step 1: Understand pytest-html functionality

   pytest-html is a plugin that creates HTML reports summarizing test results.

2. Step 2: Identify the main use

   The main use is to generate readable reports, not to speed up tests or convert code.

3. Final Answer:

   To generate easy-to-read HTML reports of test results -> Option D

4. Quick Check:

   pytest-html = HTML reports [OK]

Hint: Remember: pytest-html = HTML report generator [OK]

Common Mistakes:

• Thinking pytest-html speeds up tests
• Confusing report generation with test execution
• Assuming tests are written in HTML

2. Which command correctly generates an HTML report named report.html using pytest?

easy

A. pytest --report=report.html

B. pytest -html report.html

C. pytest --html=report.html

D. pytest -r html=report.html

Solution

1. Step 1: Recall pytest-html command syntax

   The correct syntax to generate an HTML report is pytest --html=filename.html.

2. Step 2: Match the options

   Only pytest --html=report.html matches the correct syntax exactly.

3. Final Answer:

   pytest --html=report.html -> Option C

4. Quick Check:

   Use --html=filename.html for reports [OK]

Hint: Use double dash and equals for HTML report file [OK]

Common Mistakes:

• Using single dash instead of double dash
• Using incorrect option names like --report
• Missing equals sign between option and filename

3. Given this pytest command: pytest --html=results.html, what will happen after the tests finish?

medium

A. Tests will run and output will be printed only in the console

B. An HTML file named results.html will be created with test results

C. Tests will run but no report will be generated

D. An error will occur because the command is invalid

Solution

1. Step 1: Understand the command effect

   The command pytest --html=results.html tells pytest to run tests and save results in an HTML file named results.html.

2. Step 2: Identify the expected output

   After tests finish, the HTML report file is created for easy viewing.

3. Final Answer:

   An HTML file named results.html will be created with test results -> Option B

4. Quick Check:

   --html=filename creates HTML report file [OK]

Hint: --html=filename always creates HTML report file [OK]

Common Mistakes:

• Thinking no report is generated
• Expecting output only in console
• Assuming command syntax is wrong

4. You ran pytest --html=report.html but no HTML report was created. What is the most likely cause?

medium

A. pytest-html plugin is not installed

B. The command syntax is incorrect

C. Tests did not run due to syntax errors

D. HTML reports are disabled by default

Solution

1. Step 1: Check plugin requirement

   pytest-html must be installed for --html option to work.

2. Step 2: Analyze other options

   The command syntax is correct, tests can run without errors, and reports are not disabled by default.

3. Final Answer:

   pytest-html plugin is not installed -> Option A

4. Quick Check:

   Missing plugin causes no report [OK]

Hint: Install pytest-html plugin to enable reports [OK]

Common Mistakes:

• Assuming command syntax is wrong
• Thinking reports are off by default
• Ignoring plugin installation requirement

5. You want to generate an HTML report with pytest that includes extra environment info like Python version and OS. Which approach is best?

hard

A. Use pytest --html=report.html --self-contained-html and add environment info via pytest hooks

B. Run pytest --html=report.html only; environment info is added automatically

C. Manually edit the HTML report after generation to add environment info

D. Use pytest --html=report.html --env-info option

Solution

1. Step 1: Understand pytest-html capabilities

   pytest-html can include environment info if you add it via hooks in your test setup.

2. Step 2: Evaluate options

   Use pytest --html=report.html --self-contained-html and add environment info via pytest hooks uses the correct command and mentions adding info via hooks, which is the recommended way. Run pytest --html=report.html only; environment info is added automatically is incorrect because environment info is not automatic. Manually edit the HTML report after generation to add environment info is manual and error-prone. Use pytest --html=report.html --env-info option is invalid; no such option exists.

3. Final Answer:

   Use pytest --html=report.html --self-contained-html and add environment info via pytest hooks -> Option A

4. Quick Check:

   Add env info via hooks + --html [OK]

Hint: Add environment info via hooks, not command options [OK]

Common Mistakes:

• Expecting environment info added automatically
• Trying to edit HTML manually
• Using non-existent command options