pytest-html for HTML reports - Test Execution Trace

Test Overview

This test runs a simple function check and generates an HTML report using pytest-html plugin. It verifies that the test passes and the report is created.

Test Code - pytest

PyTest

import pytest

def add(a, b):
    return a + b

def test_add():
    assert add(2, 3) == 5

# To run this test and generate HTML report, use:
# pytest --html=report.html --self-contained-html

Execution Trace - 5 Steps

Step	Action	System State	Assertion	Result
1	Test runner starts pytest with HTML report option	Terminal ready to run pytest command	—	PASS
2	Pytest discovers test_add function	Test function test_add found in test file	—	PASS
3	Pytest executes test_add	Running test_add which calls add(2, 3)	Check if add(2, 3) == 5	PASS
4	Test passes as assertion is true	Test completed successfully	assert 5 == 5	PASS
5	pytest-html plugin generates report.html file	HTML report file created with test results summary	Report file exists and contains test summary	PASS

Failure Scenario

Failing Condition: Assertion in test_add fails (e.g., add(2, 3) != 5)

Execution Trace Quiz - 3 Questions

What does the pytest-html plugin do in this test?

A Generates an HTML report file with test results

B Runs the test functions automatically

C Fixes failing tests

D Adds new test cases

Key Result

Using pytest-html helps create easy-to-read HTML reports that summarize test results, making it simple to share and review test outcomes.

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