Coverage report formats (terminal, HTML, XML) in PyTest

Introduction

Coverage reports show which parts of your code were tested. They help you find untested code so you can improve your tests.

You want to see test coverage results quickly in the terminal after running tests.

You need a detailed, easy-to-read report to share with your team using HTML format.

You want to integrate coverage results with other tools that read XML reports.

You want to check which lines of code are not covered by tests to improve quality.

Syntax

PyTest

pytest --cov=your_package --cov-report=term
pytest --cov=your_package --cov-report=html
pytest --cov=your_package --cov-report=xml

term shows coverage summary in the terminal.

html creates a detailed report you open in a browser.

xml creates an XML report for integration with other tools.

Examples

Run tests and show coverage summary in the terminal.

PyTest

pytest --cov=myapp --cov-report=term

Run tests and generate an HTML report in the htmlcov folder.

PyTest

pytest --cov=myapp --cov-report=html

Run tests and create an XML report named coverage.xml.

PyTest

pytest --cov=myapp --cov-report=xml

Sample Program

This simple test checks the add function. Running pytest with coverage and term report shows coverage summary in the terminal.

PyTest

# test_sample.py

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

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

# Run coverage with terminal report:
# pytest --cov=. --cov-report=term

Important Notes

You can combine multiple reports by repeating --cov-report, e.g., --cov-report=term --cov-report=html.

HTML reports are saved in the htmlcov folder by default.

XML reports are useful for CI tools like Jenkins or SonarQube.

Summary

Coverage reports help find untested code.

Terminal reports show quick summaries.

HTML and XML reports provide detailed and shareable formats.

Practice

1. What is the main purpose of a coverage report in pytest?

easy

A. To generate test data automatically

B. To run tests faster by skipping some tests

C. To fix bugs in the code automatically

D. To show which parts of the code were tested and which were not

Solution

1. Step 1: Understand coverage report purpose

   Coverage reports show which lines or parts of code were executed during tests.

2. Step 2: Compare options with coverage purpose

   Only To show which parts of the code were tested and which were not correctly describes this purpose; others describe unrelated actions.

3. Final Answer:

   To show which parts of the code were tested and which were not -> Option D

4. Quick Check:

   Coverage report = tested code visibility [OK]

Hint: Coverage reports show tested vs untested code [OK]

Common Mistakes:

• Confusing coverage with test execution speed
• Thinking coverage generates test data
• Believing coverage fixes bugs automatically

2. Which pytest command option generates an HTML coverage report?

easy

A. --cov-report=xml

B. --cov-report=summary

C. --cov-report=html

D. --cov-report=term

Solution

1. Step 1: Recall pytest coverage report options

   Common options include 'term' for terminal, 'html' for HTML, and 'xml' for XML reports.

2. Step 2: Match option to HTML report

   Only '--cov-report=html' generates an HTML report.

3. Final Answer:

   --cov-report=html -> Option C

4. Quick Check:

   HTML report option = --cov-report=html [OK]

Hint: HTML report uses --cov-report=html option [OK]

Common Mistakes:

• Using --cov-report=xml for HTML report
• Confusing term with html option
• Using non-existent --cov-report=summary

3. Given this pytest command:
pytest --cov=myapp --cov-report=term-missing
What will the terminal output show?

medium

A. An HTML file opened in the browser

B. A summary of coverage with missing lines shown

C. An XML file saved to disk

D. No coverage information displayed

Solution

1. Step 1: Understand --cov-report=term-missing

   This option shows coverage summary in terminal and highlights missing lines.

2. Step 2: Match output to options

   A summary of coverage with missing lines shown matches terminal summary with missing lines; others describe HTML, XML, or no output.

3. Final Answer:

   A summary of coverage with missing lines shown -> Option B

4. Quick Check:

   term-missing = terminal summary with missing lines [OK]

Hint: term-missing shows missing lines in terminal [OK]

Common Mistakes:

• Thinking term-missing opens HTML report
• Expecting XML output from term-missing
• Assuming no coverage info is shown

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

medium

A. The HTML report is saved in the current directory as 'htmlcov'

B. You forgot to install the pytest-cov plugin

C. You need to add --cov-report=xml to generate HTML

D. HTML reports are not supported by pytest

Solution

1. Step 1: Check where HTML report is saved

   By default, pytest-cov saves HTML reports in 'htmlcov' folder in current directory.

2. Step 2: Understand common confusion

   Users may think no report generated if they don't check 'htmlcov' folder; plugin installation is needed but question assumes it is installed.

3. Final Answer:

   The HTML report is saved in the current directory as 'htmlcov' -> Option A

4. Quick Check:

   HTML report folder = htmlcov [OK]

Hint: HTML report saved in 'htmlcov' folder by default [OK]

Common Mistakes:

• Assuming HTML report appears in terminal
• Forgetting to look in 'htmlcov' folder
• Thinking XML option is needed for HTML

5. You want to share coverage results with a CI tool that requires XML input. Which pytest command correctly generates the XML coverage report file?

hard

A. pytest --cov=myapp --cov-report=xml

B. pytest --cov=myapp --cov-report=html

C. pytest --cov=myapp --cov-report=term

D. pytest --cov=myapp --cov-report=term-missing

Solution

1. Step 1: Identify XML report option

   The '--cov-report=xml' option generates coverage results in XML format.

2. Step 2: Match option to CI tool requirement

   CI tools needing XML input require this exact option; others generate HTML or terminal output.

3. Final Answer:

   pytest --cov=myapp --cov-report=xml -> Option A

4. Quick Check:

   XML report option = --cov-report=xml [OK]

Hint: Use --cov-report=xml for CI XML coverage [OK]

Common Mistakes:

• Using HTML or terminal options for XML output
• Not specifying any --cov-report option
• Confusing term-missing with XML