These changes are listed in decreasing version number order. Note this can be different from a strict chronological order when there are two branches in development at the same time, such as 4.5.x and 5.0.

See :ref:`migrating` for significant changes that might be required when upgrading your version of coverage.py.

Nothing yet.

• Fix: the LCOV report code assumed that a branch line that took no branches meant that the entire line was unexecuted. This isn't true in a few cases: the line might always raise an exception, or might have been optimized away. Fixes issue 1896.
• Fix: similarly, the HTML report will now explain that a line that jumps to none of its expected destinations must have always raised an exception. Previously, it would say something nonsensical like, "line 4 didn't jump to line 5 because line 4 was never true, and it didn't jump to line 7 because line 4 was always true." This was also shown in issue 1896.

• Fix: ugh, the other assert from 7.6.5 can also be encountered in the wild, so it's been restored to a conditional. Sorry for the churn.

• One of the new asserts from 7.6.5 caused problems in real projects, as reported in issue 1891. The assert has been removed.

• Fix: fine-tuned the exact Python version (3.12.6) when exiting from with statements changed how they traced. This affected whether people saw the fix for issue 1880.
• Fix: isolate our code more from mocking in the os module that in rare cases can cause bizarre behavior.
• Refactor: some code unreachable code paths in parser.py were changed to asserts. If you encounter any of these, please let me know!

• Fix: multi-line with statements could cause contained branches to be incorrectly marked as missing (issue 1880). This is now fixed.

• Fix: nested context managers could incorrectly be analyzed to flag a missing branch on the last context manager, as described in issue 1876. This is now fixed.
• Fix: the missing branch message about not exiting a module had an extra "didn't," as described in issue 1873. This is now fixed.

• Dropped support for Python 3.8 and PyPy 3.8.
• Fix: a final wildcard match/case clause assigning to a name (case _ as value) was incorrectly marked as a missing branch. This is now fixed, closing issue 1860.
• Fewer things are considered branches now. Lambdas, comprehensions, and generator expressions are no longer marked as missing branches if they don't complete execution. Closes issue 1852.
• Fix: the HTML report didn't properly show multi-line f-strings that end with a backslash continuation. This is now fixed, closing issue 1836, thanks to LiuYinCarl and Marco Ricci.
• Fix: the LCOV report now has correct line numbers (fixing issue 1846) and better branch descriptions for BRDA records (fixing issue 1850). There are other changes to lcov also, including a new configuration option :ref:`line_checksums <config_lcov_line_checksums>` to control whether line checksums are included in the lcov report. The default is false. To keep checksums set it to true. All this work is thanks to Zack Weinberg (pull 1849 and pull 1851).
• Fixed the docs for multi-line regex exclusions, closing issue 1863.
• Fixed a potential crash in the C tracer, closing issue 1835, thanks to Jan Kühle.

• Fix: coverage used to fail when measuring code using :func:`runpy.run_path <python:runpy.run_path>` with a :class:`Path <python:pathlib.Path>` argument. This is now fixed, thanks to Ask Hjorth Larsen.
• Fix: backslashes preceding a multi-line backslashed string could confuse the HTML report. This is now fixed, thanks to LiuYinCarl.
• Now we publish wheels for Python 3.13, both regular and free-threaded.

• Exclusion patterns can now be multi-line, thanks to Daniel Diniz. This enables many interesting exclusion use-cases, including those requested in issues 118 (entire files), 996 (multiple lines only when appearing together), 1741 (remainder of a function), and 1803 (arbitrary sequence of marked lines). See the :ref:`multi_line_exclude` section of the docs for more details and examples.
• The JSON report now includes per-function and per-class coverage information. Thanks to Daniel Diniz for getting the work started. This closes issue 1793 and issue 1532.
• Fixed an incorrect calculation of "(no class)" lines in the HTML classes report.
• Python 3.13.0b3 is supported.

• If you attempt to combine statement coverage data with branch coverage data, coverage.py used to fail with the message "Can't combine arc data with line data" or its reverse, "Can't combine line data with arc data." These messages used internal terminology, making it hard for people to understand the problem. They are now changed to mention "branch coverage data" and "statement coverage data."
• Fixed a minor branch coverage problem with wildcard match/case cases using names or guard clauses.
• Started testing on 3.13 free-threading (nogil) builds of Python. I'm not claiming full support yet. Closes issue 1799.

• Performance improvements for combining data files, especially when measuring line coverage. A few different quadratic behaviors were eliminated. In one extreme case of combining 700+ data files, the time dropped from more than three hours to seven minutes. Thanks for Kraken Tech for funding the fix.
• Performance improvements for generating HTML reports, with a side benefit of reducing memory use, closing issue 1791. Thanks to Daniel Diniz for helping to diagnose the problem.

• Fix: nested matches of exclude patterns could exclude too much code, as reported in issue 1779. This is now fixed.
• Changed: previously, coverage.py would consider a module docstring to be an executable statement if it appeared after line 1 in the file, but not executable if it was the first line. Now module docstrings are never counted as executable statements. This can change coverage.py's count of the number of statements in a file, which can slightly change the coverage percentage reported.
• In the HTML report, the filter term and "hide covered" checkbox settings are remembered between viewings, thanks to Daniel Diniz.
• Python 3.13.0b1 is supported.
• Fix: parsing error handling is improved to ensure bizarre source files are handled gracefully, and to unblock oss-fuzz fuzzing, thanks to Liam DeVoe. Closes issue 1787.

• Fix: a pragma comment on the continuation lines of a multi-line statement now excludes the statement and its body, the same as if the pragma is on the first line. This closes issue 754. The fix was contributed by Daniel Diniz.
• Fix: very complex source files like this one could cause a maximum recursion error when creating an HTML report. This is now fixed, closing issue 1774.
• HTML report improvements:
  • Support files (JavaScript and CSS) referenced by the HTML report now have hashes added to their names to ensure updated files are used instead of stale cached copies.
  • Missing branch coverage explanations that said "the condition was never false" now read "the condition was always true" because it's easier to understand.
  • Column sort order is remembered better as you move between the index pages, fixing issue 1766. Thanks, Daniel Diniz.

• Added initial support for function and class reporting in the HTML report. There are now three index pages which link to each other: files, functions, and classes. Other reports don't yet have this information, but it will be added in the future where it makes sense. Feedback gladly accepted! Finishes issue 780.
• Other HTML report improvements:
  • There is now a "hide covered" checkbox to filter out 100% files, finishing issue 1384.
  • The index page is always sorted by one of its columns, with clearer indications of the sorting.
  • The "previous file" shortcut key didn't work on the index page, but now it does, fixing issue 1765.
• The debug output showing which configuration files were tried now shows absolute paths to help diagnose problems where settings aren't taking effect, and is renamed from "attempted_config_files" to the more logical "config_files_attempted."
• Python 3.13.0a6 is supported.

• Fix: in some cases, even with [run] relative_files=True, a data file could be created with absolute path names. When combined with other relative data files, it was random whether the absolute file names would be made relative or not. If they weren't, then a file would be listed twice in reports, as detailed in issue 1752. This is now fixed: absolute file names are always made relative when combining. Thanks to Bruno Rodrigues dos Santos for support.
• Fix: the last case of a match/case statement had an incorrect message if the branch was missed. It said the pattern never matched, when actually the branch is missed if the last case always matched.
• Fix: clicking a line number in the HTML report now positions more accurately.
• Fix: the report:format setting was defined as a boolean, but should be a string. Thanks, Tanaydin Sirin. It is also now documented on the :ref:`configuration page <config_report_format>`.

• Fix: in some cases, coverage could fail with a RuntimeError: "Set changed size during iteration." This is now fixed, closing issue 1733.

• Fix: setting COVERAGE_CORE=sysmon no longer errors on 3.11 and lower, thanks Hugo van Kemenade. It now issues a warning that sys.monitoring is not available and falls back to the default core instead.

• Python 3.13.0a3 is supported.
• Fix: the JSON report now includes an explicit format version number, closing issue 1732.

• In Python 3.12 and above, you can try an experimental core based on the new :mod:`sys.monitoring <python:sys.monitoring>` module by defining a COVERAGE_CORE=sysmon environment variable. This should be faster for line coverage, but not for branch coverage, and plugins and dynamic contexts are not yet supported with it. I am very interested to hear how it works (or doesn't!) for you.

• Fix: the change for multi-line signature exclusions in 7.3.3 broke other forms of nested clauses being excluded properly. This is now fixed, closing issue 1713.
• Fix: in the HTML report, selecting code for copying won't select the line numbers also. Thanks, Robert Harris.

• Fix: function definitions with multi-line signatures can now be excluded by matching any of the lines, closing issue 684. Thanks, Jan Rusak, Maciej Kowalczyk and Joanna Ejzel.
• Fix: XML reports could fail with a TypeError if files had numeric components that were duplicates except for leading zeroes, like file1.py and file001.py. Fixes issue 1709.
• The coverage annotate command used to announce that it would be removed in a future version. Enough people got in touch to say that they use it, so it will stay. Don't expect it to keep up with other new features though.
• Added new :ref:`debug options <cmd_run_debug>`:
  • pytest writes the pytest test name into the debug output.
  • dataop2 writes the full data being added to CoverageData objects.

• The coverage lcov command ignored the [report] exclude_lines and [report] exclude_also settings (issue 1684). This is now fixed, thanks Jacqueline Lee.
• Sometimes SQLite will create journal files alongside the coverage.py database files. These are ephemeral, but could be mistakenly included when combining data files. Now they are always ignored, fixing issue 1605. Thanks to Brad Smith for suggesting fixes and providing detailed debugging.
• On Python 3.12+, we now disable SQLite writing journal files, which should be a little faster.
• The new 3.12 soft keyword type is properly bolded in HTML reports.
• Removed the "fullcoverage" feature used by CPython to measure the coverage of early-imported standard library modules. CPython stopped using it in 2021, and it stopped working completely in Python 3.13.

• The semantics of stars in file patterns has been clarified in the docs. A leading or trailing star matches any number of path components, like a double star would. This is different than the behavior of a star in the middle of a pattern. This discrepancy was identified by Sviatoslav Sydorenko, who provided patient detailed diagnosis and graciously agreed to a pragmatic resolution.
• The API docs were missing from the last version. They are now restored.

• Added a :meth:`.Coverage.collect` context manager to start and stop coverage data collection.
• Dropped support for Python 3.7.
• Fix: in unusual circumstances, SQLite cannot be set to asynchronous mode. Coverage.py would fail with the error Safety level may not be changed inside a transaction. This is now avoided, closing issue 1646. Thanks to Michael Bell for the detailed bug report.
• Docs: examples of configuration files now include separate examples for the different syntaxes: .coveragerc, pyproject.toml, setup.cfg, and tox.ini.
• Fix: added nosemgrep comments to our JavaScript code so that semgrep-based SAST security checks won't raise false alarms about security problems that aren't problems.
• Added a CITATION.cff file, thanks to Ken Schackart.

• Fix: reverted a change from 6.4.3 that helped Cython, but also increased the size of data files when using dynamic contexts, as described in the now-fixed issue 1586. The problem is now avoided due to a recent change (issue 1538). Thanks to Anders Kaseorg and David Szotten for persisting with problem reports and detailed diagnoses.
• Wheels are now provided for CPython 3.12.

• Fix: the lcov command could raise an IndexError exception if a file is translated to Python but then executed under its own name. Jinja2 does this when rendering templates. Fixes issue 1553.
• Python 3.12 beta 1 now inlines comprehensions. Previously they were compiled as invisible functions and coverage.py would warn you if they weren't completely executed. This no longer happens under Python 3.12.
• Fix: the coverage debug sys command includes some environment variables in its output. This could have included sensitive data. Those values are now hidden with asterisks, closing issue 1628.

• Fix: html_report() could fail with an AttributeError on isatty if run in an unusual environment where sys.stdout had been replaced. This is now fixed.

PyCon 2023 sprint fixes!

• Fix: with relative_files = true, specifying a specific file to include or omit wouldn't work correctly (issue 1604). This is now fixed, with testing help by Marc Gibbons.
• Fix: the XML report would have an incorrect <source> element when using relative files and the source option ended with a slash (issue 1541). This is now fixed, thanks to Kevin Brown-Silva.
• When the HTML report location is printed to the terminal, it's now a terminal-compatible URL, so that you can click the location to open the HTML file in your browser. Finishes issue 1523 thanks to Ricardo Newbery.
• Docs: a new :ref:`Migrating page <migrating>` with details about how to migrate between major versions of coverage.py. It currently covers the wildcard changes in 7.x. Thanks, Brian Grohe.

• Fix: the :ref:`config_run_sigterm` setting was meant to capture data if a process was terminated with a SIGTERM signal, but it didn't always. This was fixed thanks to Lewis Gaul, closing issue 1599.
• Performance: HTML reports with context information are now much more compact. File sizes are typically as small as one-third the previous size, but can be dramatically smaller. This closes issue 1584 thanks to Oleh Krehel.
• Development dependencies no longer use hashed pins, closing issue 1592.

• Fix: if a virtualenv was created inside a source directory, and a sourced package was installed inside the virtualenv, then all of the third-party packages inside the virtualenv would be measured. This was incorrect, but has now been fixed: only the specified packages will be measured, thanks to Manuel Jacob.
• Fix: the coverage lcov command could create a .lcov file with incorrect LF (lines found) and LH (lines hit) totals. This is now fixed, thanks to Ian Moore.
• Fix: the coverage xml command on Windows could create a .xml file with duplicate <package> elements. This is now fixed, thanks to Benjamin Parzella, closing issue 1573.

• Fix: the PyPI page had broken links to documentation pages, but no longer does, closing issue 1566.
• Fix: public members of the coverage module are now properly indicated so that mypy will find them, fixing issue 1564.

• Added a new setting [report] exclude_also to let you add more exclusions without overwriting the defaults. Thanks, Alpha Chen, closing issue 1391.
• Added a :meth:`.CoverageData.purge_files` method to remove recorded data for a particular file. Contributed by Stephan Deibel.
• Fix: when reporting commands fail, they will no longer congratulate themselves with messages like "Wrote XML report to file.xml" before spewing a traceback about their failure.
• Fix: arguments in the public API that name file paths now accept pathlib.Path objects. This includes the data_file and config_file arguments to the Coverage constructor and the basename argument to CoverageData. Closes issue 1552.
• Fix: In some embedded environments, an IndexError could occur on stop() when the originating thread exits before completion. This is now fixed, thanks to Russell Keith-Magee, closing issue 1542.
• Added a py.typed file to announce our type-hintedness. Thanks, KotlinIsland.

• Added: the debug output file can now be specified with [run] debug_file in the configuration file. Closes issue 1319.
• Performance: fixed a slowdown with dynamic contexts that's been around since 6.4.3. The fix closes issue 1538. Thankfully this doesn't break the Cython change that fixed issue 972. Thanks to Mathieu Kniewallner for the deep investigative work and comprehensive issue report.
• Typing: all product and test code has type annotations.

• Fix: On Python 3.7, a file with type annotations but no from __future__ import annotations would be missing statements in the coverage report. This is now fixed, closing issue 1524.

• Performance: an internal cache of file names was accidentally disabled, resulting in sometimes drastic reductions in performance. This is now fixed, closing issue 1527. Thanks to Ivan Ciuvalschii for the reproducible test case.

• Fix: when using pytest-cov or pytest-xdist, or perhaps both, the combining step could fail with assert row is not None using 7.0.2. This was due to a race condition that has always been possible and is still possible. In 7.0.1 and before, the error was silently swallowed by the combining code. Now it will produce a message "Couldn't combine data file" and ignore the data file as it used to do before 7.0.2. Closes issue 1522.

• Fix: when using the [run] relative_files = True setting, a relative [paths] pattern was still being made absolute. This is now fixed, closing issue 1519.
• Fix: if Python doesn't provide tomllib, then TOML configuration files can only be read if coverage.py is installed with the [toml] extra. Coverage.py will raise an error if TOML support is not installed when it sees your settings are in a .toml file. But it didn't understand that [tools.coverage] was a valid section header, so the error wasn't reported if you used that header, and settings were silently ignored. This is now fixed, closing issue 1516.
• Fix: adjusted how decorators are traced on PyPy 7.3.10, fixing issue 1515.
• Fix: the coverage lcov report did not properly implement the --fail-under=MIN option. This has been fixed.
• Refactor: added many type annotations, including a number of refactorings. This should not affect outward behavior, but they were a bit invasive in some places, so keep your eyes peeled for oddities.
• Refactor: removed the vestigial and long untested support for Jython and IronPython.

• When checking if a file mapping resolved to a file that exists, we weren't considering files in .whl files. This is now fixed, closing issue 1511.
• File pattern rules were too strict, forbidding plus signs and curly braces in directory and file names. This is now fixed, closing issue 1513.
• Unusual Unicode or control characters in source files could prevent reporting. This is now fixed, closing issue 1512.
• The PyPy wheel now installs on PyPy 3.7, 3.8, and 3.9, closing issue 1510.

Nothing new beyond 7.0.0b1.

A number of changes have been made to file path handling, including pattern matching and path remapping with the [paths] setting (see :ref:`config_paths`). These changes might affect you, and require you to update your settings.

(This release includes the changes from 6.6.0b1, since 6.6.0 was never released.)

• Changes to file pattern matching, which might require updating your configuration:
  • Previously, * would incorrectly match directory separators, making precise matching difficult. This is now fixed, closing issue 1407.
  • Now ** matches any number of nested directories, including none.
• Improvements to combining data files when using the :ref:`config_run_relative_files` setting, which might require updating your configuration:
  • During coverage combine, relative file paths are implicitly combined without needing a [paths] configuration setting. This also fixed issue 991.
  • A [paths] setting like */foo will now match foo/bar.py so that relative file paths can be combined more easily.
  • The :ref:`config_run_relative_files` setting is properly interpreted in more places, fixing issue 1280.
• When remapping file paths with [paths], a path will be remapped only if the resulting path exists. The documentation has long said the prefix had to exist, but it was never enforced. This fixes issue 608, improves issue 649, and closes issue 757.
• Reporting operations now implicitly use the [paths] setting to remap file paths within a single data file. Combining multiple files still requires the coverage combine step, but this simplifies some single-file situations. Closes issue 1212 and issue 713.
• The coverage report command now has a --format= option. The original style is now --format=text, and is the default.
  • Using --format=markdown will write the table in Markdown format, thanks to Steve Oswald, closing issue 1418.
  • Using --format=total will write a single total number to the output. This can be useful for making badges or writing status updates.
• Combining data files with coverage combine now hashes the data files to skip files that add no new information. This can reduce the time needed. Many details affect the speed-up, but for coverage.py's own test suite, combining is about 40% faster. Closes issue 1483.
• When searching for completely un-executed files, coverage.py uses the presence of __init__.py files to determine which directories have source that could have been imported. However, implicit namespace packages don't require __init__.py. A new setting [report] include_namespace_packages tells coverage.py to consider these directories during reporting. Thanks to Felix Horvat for the contribution. Closes issue 1383 and issue 1024.
• Fixed environment variable expansion in pyproject.toml files. It was overly broad, causing errors outside of coverage.py settings, as described in issue 1481 and issue 1345. This is now fixed, but in rare cases will require changing your pyproject.toml to quote non-string values that use environment substitution.
• An empty file has a coverage total of 100%, but used to fail with --fail-under. This has been fixed, closing issue 1470.
• The text report table no longer writes out two separator lines if there are no files listed in the table. One is plenty.
• Fixed a mis-measurement of a strange use of wildcard alternatives in match/case statements, closing issue 1421.
• Fixed internal logic that prevented coverage.py from running on implementations other than CPython or PyPy (issue 1474).
• The deprecated [run] note setting has been completely removed.

(Note: 6.6.0 final was never released. These changes are part of 7.0.0b1.)

• Changes to file pattern matching, which might require updating your configuration:
  • Previously, * would incorrectly match directory separators, making precise matching difficult. This is now fixed, closing issue 1407.
  • Now ** matches any number of nested directories, including none.
• Improvements to combining data files when using the :ref:`config_run_relative_files` setting:
  • During coverage combine, relative file paths are implicitly combined without needing a [paths] configuration setting. This also fixed issue 991.
  • A [paths] setting like */foo will now match foo/bar.py so that relative file paths can be combined more easily.
  • The setting is properly interpreted in more places, fixing issue 1280.
• Fixed environment variable expansion in pyproject.toml files. It was overly broad, causing errors outside of coverage.py settings, as described in issue 1481 and issue 1345. This is now fixed, but in rare cases will require changing your pyproject.toml to quote non-string values that use environment substitution.
• Fixed internal logic that prevented coverage.py from running on implementations other than CPython or PyPy (issue 1474).

• The JSON report now includes details of which branches were taken, and which are missing for each file. Thanks, Christoph Blessing. Closes issue 1425.
• Starting with coverage.py 6.2, class statements were marked as a branch. This wasn't right, and has been reverted, fixing issue 1449. Note this will very slightly reduce your coverage total if you are measuring branch coverage.
• Packaging is now compliant with PEP 517, closing issue 1395.
• A new debug option --debug=pathmap shows details of the remapping of paths that happens during combine due to the [paths] setting.
• Fix an internal problem with caching of invalid Python parsing. Found by OSS-Fuzz, fixing their bug 50381.

• Wheels are now provided for Python 3.11.

• Fix a failure when combining data files if the file names contained glob-like patterns. Thanks, Michael Krebs and Benjamin Schubert.
• Fix a messaging failure when combining Windows data files on a different drive than the current directory, closing issue 1428. Thanks, Lorenzo Micò.
• Fix path calculations when running in the root directory, as you might do in a Docker container. Thanks Arthur Rio.
• Filtering in the HTML report wouldn't work when reloading the index page. This is now fixed. Thanks, Marc Legendre.
• Fix a problem with Cython code measurement, closing issue 972. Thanks, Matus Valo.

• Updated for a small change in Python 3.11.0 beta 4: modules now start with a line with line number 0, which is ignored. This line cannot be executed, so coverage totals were thrown off. This line is now ignored by coverage.py, but this also means that truly empty modules (like __init__.py) have no lines in them, rather than one phantom line. Fixes issue 1419.
• Internal debugging data added to sys.modules is now an actual module, to avoid confusing code that examines everything in sys.modules. Thanks, Yilei Yang.

• Greatly improved performance on PyPy, and other environments that need the pure Python trace function. Thanks, Carl Friedrich Bolz-Tereick (pull 1381 and pull 1388). Slightly improved performance when using the C trace function, as most environments do. Closes issue 1339.
• The conditions for using tomllib from the standard library have been made more precise, so that 3.11 alphas will continue to work. Closes issue 1390.

• A new setting, :ref:`config_run_sigterm`, controls whether a SIGTERM signal handler is used. In 6.3, the signal handler was always installed, to capture data at unusual process ends. Unfortunately, this introduced other problems (see issue 1310). Now the signal handler is only used if you opt-in by setting [run] sigterm = true.
• Small changes to the HTML report:
  • Added links to next and previous file, and more keyboard shortcuts: [ and ] for next file and previous file; u for up to the index; and ? to open/close the help panel. Thanks, J. M. F. Tsang.
  • The time stamp and version are displayed at the top of the report. Thanks, Ammar Askar. Closes issue 1351.
• A new debug option debug=sqldata adds more detail to debug=sql, logging all the data being written to the database.
• Previously, running coverage report (or any of the reporting commands) in an empty directory would create a .coverage data file. Now they do not, fixing issue 1328.
• On Python 3.11, the [toml] extra no longer installs tomli, instead using tomllib from the standard library. Thanks Shantanu.
• In-memory CoverageData objects now properly update(), closing issue 1323.

• Fix: Coverage.py now builds successfully on CPython 3.11 (3.11.0b1) again. Closes issue 1367. Some results for generators may have changed.

• Fix: adapt to pypy3.9's decorator tracing behavior. It now traces function decorators like CPython 3.8: both the @-line and the def-line are traced. Fixes issue 1326.
• Debug: added pybehave to the list of :ref:`coverage debug <cmd_debug>` and :ref:`cmd_run_debug` options.
• Fix: show an intelligible error message if --concurrency=multiprocessing is used without a configuration file. Closes issue 1320.

• Fix: deadlocks could occur when terminating processes. Some of these deadlocks (described in issue 1310) are now fixed.
• Fix: a signal handler was being set from multiple threads, causing an error: "ValueError: signal only works in main thread". This is now fixed, closing issue 1312.
• Fix: --precision on the command-line was being ignored while considering --fail-under. This is now fixed, thanks to Marcelo Trylesinski.
• Fix: releases no longer provide 3.11.0-alpha wheels. Coverage.py uses CPython internal fields which are moving during the alpha phase. Fixes issue 1316.

• Feature: Added the lcov command to generate reports in LCOV format. Thanks, Bradley Burns. Closes issues 587 and 626.
• Feature: the coverage data file can now be specified on the command line with the --data-file option in any command that reads or writes data. This is in addition to the existing COVERAGE_FILE environment variable. Closes issue 624. Thanks, Nikita Bloshchanevich.
• Feature: coverage measurement data will now be written when a SIGTERM signal is received by the process. This includes :meth:`Process.terminate <python:multiprocessing.Process.terminate>`, and other ways to terminate a process. Currently this is only on Linux and Mac; Windows is not supported. Fixes issue 1307.
• Dropped support for Python 3.6, which reached end-of-life on 2021-12-23.
• Updated Python 3.11 support to 3.11.0a4, fixing issue 1294.
• Fix: the coverage data file is now created in a more robust way, to avoid problems when multiple processes are trying to write data at once. Fixes issues 1303 and 883.
• Fix: a .gitignore file will only be written into the HTML report output directory if the directory is empty. This should prevent certain unfortunate accidents of writing the file where it is not wanted.
• Releases now have MacOS arm64 wheels for Apple Silicon, fixing issue 1288.

• Feature: Now the --concurrency setting can have a list of values, so that threads and another lightweight threading package can be measured together, such as --concurrency=gevent,thread. Closes issue 1012 and issue 1082. This also means that thread must be explicitly specified in some cases that used to be implicit such as --concurrency=multiprocessing, which must be changed to --concurrency=multiprocessing,thread.
• Fix: A module specified as the source setting is imported during startup, before the user program imports it. This could cause problems if the rest of the program isn't ready yet. For example, issue 1203 describes a Django setting that is accessed before settings have been configured. Now the early import is wrapped in a try/except so errors then don't stop execution.
• Fix: A colon in a decorator expression would cause an exclusion to end too early, preventing the exclusion of the decorated function. This is now fixed.
• Fix: The HTML report now will not overwrite a .gitignore file that already exists in the HTML output directory (follow-on for issue 1244).
• API: The exceptions raised by Coverage.py have been specialized, to provide finer-grained catching of exceptions by third-party code.
• API: Using suffix=False when constructing a Coverage object with multiprocessing wouldn't suppress the data file suffix (issue 989). This is now fixed.
• Debug: The coverage debug data command will now sniff out combinable data files, and report on all of them.
• Debug: The coverage debug command used to accept a number of topics at a time, and show all of them, though this was never documented. This no longer works, to allow for command-line options in the future.

• Python 3.11 is supported (tested with 3.11.0a2). One still-open issue has to do with exits through with-statements.
• Fix: When remapping file paths through the [paths] setting while combining, the [run] relative_files setting was ignored, resulting in absolute paths for remapped file names (issue 1147). This is now fixed.
• Fix: Complex conditionals over excluded lines could have incorrectly reported a missing branch (issue 1271). This is now fixed.
• Fix: More exceptions are now handled when trying to parse source files for reporting. Problems that used to terminate coverage.py can now be handled with [report] ignore_errors. This helps with plugins failing to read files (django_coverage_plugin issue 78).
• Fix: Removed another vestige of jQuery from the source tarball (issue 840).
• Fix: Added a default value for a new-to-6.x argument of an internal class. This unsupported class is being used by coveralls (issue 1273). Although I'd rather not "fix" unsupported interfaces, it's actually nicer with a default value.

• Fix: The sticky header on the HTML report didn't work unless you had branch coverage enabled. This is now fixed: the sticky header works for everyone. (Do people still use coverage without branch measurement!? j/k)
• Fix: When using explicitly declared namespace packages, the "already imported a file that will be measured" warning would be issued (issue 888). This is now fixed.

• Deprecated: The annotate command and the Coverage.annotate function will be removed in a future version, unless people let me know that they are using it. Instead, the html command gives better-looking (and more accurate) output, and the report -m command will tell you line numbers of missing lines. Please get in touch if you have a reason to use annotate over those better options: ned@nedbatchelder.com.
• Feature: Coverage now sets an environment variable, COVERAGE_RUN when running your code with the coverage run command. The value is not important, and may change in the future. Closes issue 553.
• Feature: The HTML report pages for Python source files now have a sticky header so the file name and controls are always visible.
• Feature: The xml and json commands now describe what they wrote where.
• Feature: The html, combine, xml, and json commands all accept a -q/--quiet option to suppress the messages they write to stdout about what they are doing (issue 1254).
• Feature: The html command writes a .gitignore file into the HTML output directory, to prevent the report from being committed to git. If you want to commit it, you will need to delete that file. Closes issue 1244.
• Feature: Added support for PyPy 3.8.
• Fix: More generated code is now excluded from measurement. Code such as attrs boilerplate, or doctest code, was being measured though the synthetic line numbers meant they were never reported. Once Cython was involved though, the generated .so files were parsed as Python, raising syntax errors, as reported in issue 1160. This is now fixed.
• Fix: When sorting human-readable names, numeric components are sorted correctly: file10.py will appear after file9.py. This applies to file names, module names, environment variables, and test contexts.
• Performance: Branch coverage measurement is faster, though you might only notice on code that is executed many times, such as long-running loops.
• Build: jQuery is no longer used or vendored (issue 840 and issue 1118). Huge thanks to Nils Kattenbeck (septatrix) for the conversion to vanilla JavaScript in pull request 1248.

• Namespace packages being measured weren't properly handled by the new code that ignores third-party packages. If the namespace package was installed, it was ignored as a third-party package. That problem (issue 1231) is now fixed.
• Packages named as "source packages" (with source, or source_pkgs, or pytest-cov's --cov) might have been only partially measured. Their top-level statements could be marked as un-executed, because they were imported by coverage.py before measurement began (issue 1232). This is now fixed, but the package will be imported twice, once by coverage.py, then again by your test suite. This could cause problems if importing the package has side effects.
• The :meth:`.CoverageData.contexts_by_lineno` method was documented to return a dict, but was returning a defaultdict. Now it returns a plain dict. It also no longer returns negative numbered keys.

• In 6.0, the coverage.py exceptions moved from coverage.misc to coverage.exceptions. These exceptions are not part of the public supported API, CoverageException is. But a number of other third-party packages were importing the exceptions from coverage.misc, so they are now available from there again (issue 1226).
• Changed an internal detail of how tomli is imported, so that tomli can use coverage.py for their own test suite (issue 1228).
• Defend against an obscure possibility under code obfuscation, where a function can have an argument called "self", but no local named "self" (pull request 1210). Thanks, Ben Carlsson.

• The coverage html command now prints a message indicating where the HTML report was written. Fixes issue 1195.
• The coverage combine command now prints messages indicating each data file being combined. Fixes issue 1105.
• The HTML report now includes a sentence about skipped files due to skip_covered or skip_empty settings. Fixes issue 1163.
• Unrecognized options in the configuration file are no longer errors. They are now warnings, to ease the use of coverage across versions. Fixes issue 1035.
• Fix handling of exceptions through context managers in Python 3.10. A missing exception is no longer considered a missing branch from the with statement. Fixes issue 1205.
• Fix another rarer instance of "Error binding parameter 0 - probably unsupported type." (issue 1010).
• Creating a directory for the coverage data file now is safer against conflicts when two coverage runs happen simultaneously (pull 1220). Thanks, Clément Pit-Claudel.

• Dropped support for Python 2.7, PyPy 2, and Python 3.5.
• Added support for the Python 3.10 match/case syntax.
• Data collection is now thread-safe. There may have been rare instances of exceptions raised in multi-threaded programs.
• Plugins (like the Django coverage plugin) were generating "Already imported a file that will be measured" warnings about Django itself. These have been fixed, closing issue 1150.
• Warnings generated by coverage.py are now real Python warnings.
• Using --fail-under=100 with coverage near 100% could result in the self-contradictory message total of 100 is less than fail-under=100. This bug (issue 1168) is now fixed.
• The COVERAGE_DEBUG_FILE environment variable now accepts stdout and stderr to write to those destinations.
• TOML parsing now uses the tomli library.
• Some minor changes to usually invisible details of the HTML report:
  • Use a modern hash algorithm when fingerprinting, for high-security environments (issue 1189). When generating the HTML report, we save the hash of the data, to avoid regenerating an unchanged HTML page. We used to use MD5 to generate the hash, and now use SHA-3-256. This was never a security concern, but security scanners would notice the MD5 algorithm and raise a false alarm.
  • Change how report file names are generated, to avoid leading underscores (issue 1167), to avoid rare file name collisions (issue 584), and to avoid file names becoming too long (issue 580).

Note: 5.6 final was never released. These changes are part of 6.0.

• Third-party packages are now ignored in coverage reporting. This solves a few problems:
  • Coverage will no longer report about other people's code (issue 876). This is true even when using --source=. with a venv in the current directory.
  • Coverage will no longer generate "Already imported a file that will be measured" warnings about coverage itself (issue 905).
• The HTML report uses j/k to move up and down among the highlighted chunks of code. They used to highlight the current chunk, but 5.0 broke that behavior. Now the highlighting is working again.
• The JSON report now includes percent_covered_display, a string with the total percentage, rounded to the same number of decimal places as the other reports' totals.

• coverage combine has a new option, --keep to keep the original data files after combining them. The default is still to delete the files after they have been combined. This was requested in issue 1108 and implemented in pull request 1110. Thanks, Éric Larivière.
• When reporting missing branches in coverage report, branches aren't reported that jump to missing lines. This adds to the long-standing behavior of not reporting branches from missing lines. Now branches are only reported if both the source and destination lines are executed. Closes both issue 1065 and issue 955.
• Minor improvements to the HTML report:
  • The state of the line visibility selector buttons is saved in local storage so you don't have to fiddle with them so often, fixing issue 1123.
  • It has a little more room for line numbers so that 4-digit numbers work well, fixing issue 1124.
• Improved the error message when combining line and branch data, so that users will be more likely to understand what's happening, closing issue 803.

• The text report produced by coverage report now always outputs a TOTAL line, even if only one Python file is reported. This makes regex parsing of the output easier. Thanks, Judson Neer. This had been requested a number of times (issue 1086, issue 922, issue 732).
• The skip_covered and skip_empty settings in the configuration file can now be specified in the [html] section, so that text reports and HTML reports can use separate settings. The HTML report will still use the [report] settings if there isn't a value in the [html] section. Closes issue 1090.
• Combining files on Windows across drives now works properly, fixing issue 577. Thanks, Valentin Lab.
• Fix an obscure warning from deep in the _decimal module, as reported in issue 1084.
• Update to support Python 3.10 alphas in progress, including PEP 626: Precise line numbers for debugging and other tools.

• When using --source on a large source tree, v5.x was slower than previous versions. This performance regression is now fixed, closing issue 1037.
• Mysterious SQLite errors can happen on PyPy, as reported in issue 1010. An immediate retry seems to fix the problem, although it is an unsatisfying solution.
• The HTML report now saves the sort order in a more widely supported way, fixing issue 986. Thanks, Sebastián Ramírez (pull request 1066).
• The HTML report pages now have a :ref:`Sleepy Snake <sleepy>` favicon.
• Wheels are now provided for manylinux2010, and for PyPy3 (pp36 and pp37).
• Continuous integration has moved from Travis and AppVeyor to GitHub Actions.

• The source setting has always been interpreted as either a file path or a module, depending on which existed. If both interpretations were valid, it was assumed to be a file path. The new source_pkgs setting can be used to name a package to disambiguate this case. Thanks, Thomas Grainger. Fixes issue 268.
• If a plugin was disabled due to an exception, we used to still try to record its information, causing an exception, as reported in issue 1011. This is now fixed.

The complete history is available in the coverage.py docs.