LambdaTest
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The standard in documentation-driven testing for verifiable Python examples.
doctest is a fundamental module within the Python standard library designed to verify that documentation remains synchronized with code execution. In the 2026 development landscape, it continues to serve as a critical tool for library maintainers, API developers, and technical writers who advocate for 'literate programming.' The module functions by searching for text that resembles interactive Python sessions, executing those snippets, and comparing the output against the specified expectations in the docstring. This mechanism effectively turns documentation into an executable test suite, preventing 'documentation rot'—a common issue where examples in READMEs or help strings become obsolete as code evolves. While modern frameworks like Pytest offer more robust features for complex integration testing, doctest maintains a unique market position due to its zero-dependency architecture and its ability to provide immediate, readable value to end-users consuming the documentation. It is highly optimized for verifying simple logic, tutorial snippets, and ensuring that public-facing examples are functionally correct. For 2026 AI-driven development workflows, doctest remains the primary validator for auto-generated documentation, ensuring LLM-produced code examples remain viable within project environments.
Parses and executes text strings using a simulated Python interactive shell environment.
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Uses the NORMALIZE_WHITESPACE flag to ignore minor formatting discrepancies between expected and actual output.
Replaces unpredictable parts of the output string (like hex addresses) with '...' during verification.
Native support for verifying that specific code snippets raise the expected Traceback.
Inline comments like # doctest: +SKIP or # doctest: +IGNORE_EXCEPTION_DETAIL provide granular control.
Capable of parsing ReStructuredText (.rst) and plain text files for code blocks.
Exposes a DocTestSuite class to wrap doctests into standard unittest suites.
Developers often find that documentation examples are broken because the underlying API changed.
Registry Updated:2/7/2026
New users struggle when the 'Getting Started' guide has typos or outdated logic.
Small utility functions often lack dedicated test files, leading to silent failures.