The Coverage class

class coverage.Coverage(data_file=None, data_suffix=None, cover_pylib=None, auto_data=False, timid=None, branch=None, config_file=True, source=None, omit=None, include=None, debug=None, concurrency=None)

Programmatic access to coverage.py.

To use:

from coverage import Coverage

cov = Coverage()
cov.start()
#.. call your code ..
cov.stop()
cov.html_report(directory='covhtml')
__init__(data_file=None, data_suffix=None, cover_pylib=None, auto_data=False, timid=None, branch=None, config_file=True, source=None, omit=None, include=None, debug=None, concurrency=None)

data_file is the base name of the data file to use, defaulting to ”.coverage”. data_suffix is appended (with a dot) to data_file to create the final file name. If data_suffix is simply True, then a suffix is created with the machine and process identity included.

cover_pylib is a boolean determining whether Python code installed with the Python interpreter is measured. This includes the Python standard library and any packages installed with the interpreter.

If auto_data is true, then any existing data file will be read when coverage measurement starts, and data will be saved automatically when measurement stops.

If timid is true, then a slower and simpler trace function will be used. This is important for some environments where manipulation of tracing functions breaks the faster trace function.

If branch is true, then branch coverage will be measured in addition to the usual statement coverage.

config_file determines what configuration file to read:

  • If it is ”.coveragerc”, it is interpreted as if it were True, for backward compatibility.
  • If it is a string, it is the name of the file to read. If the file can’t be read, it is an error.
  • If it is True, then a few standard files names are tried (”.coveragerc”, “setup.cfg”, “tox.ini”). It is not an error for these files to not be found.
  • If it is False, then no configuration file is read.

source is a list of file paths or package names. Only code located in the trees indicated by the file paths or package names will be measured.

include and omit are lists of file name patterns. Files that match include will be measured, files that match omit will not. Each will also accept a single string argument.

debug is a list of strings indicating what debugging information is desired.

concurrency is a string indicating the concurrency library being used in the measured code. Without this, coverage.py will get incorrect results if these libraries are in use. Valid strings are “greenlet”, “eventlet”, “gevent”, “multiprocessing”, or “thread” (the default). This can also be a list of these strings.

New in version 4.0: The concurrency parameter.

New in version 4.2: The concurrency parameter can now be a list of strings.

analysis(morf)

Like analysis2 but doesn’t return excluded line numbers.

analysis2(morf)

Analyze a module.

morf is a module or a file name. It will be analyzed to determine its coverage statistics. The return value is a 5-tuple:

  • The file name for the module.
  • A list of line numbers of executable statements.
  • A list of line numbers of excluded statements.
  • A list of line numbers of statements not run (missing from execution).
  • A readable formatted string of the missing line numbers.

The analysis uses the source file itself and the current measured coverage data.

annotate(morfs=None, directory=None, ignore_errors=None, omit=None, include=None)

Annotate a list of modules.

Each module in morfs is annotated. The source is written to a new file, named with a ”,cover” suffix, with each line prefixed with a marker to indicate the coverage of the line. Covered lines have “>”, excluded lines have “-”, and missing lines have ”!”.

See report() for other arguments.

clear_exclude(which='exclude')

Clear the exclude list.

combine(data_paths=None, strict=False)

Combine together a number of similarly-named coverage data files.

All coverage data files whose name starts with data_file (from the coverage() constructor) will be read, and combined together into the current measurements.

data_paths is a list of files or directories from which data should be combined. If no list is passed, then the data files from the directory indicated by the current data file (probably the current directory) will be combined.

If strict is true, then it is an error to attempt to combine when there are no data files to combine.

New in version 4.0: The data_paths parameter.

New in version 4.3: The strict parameter.

erase()

Erase previously-collected coverage data.

This removes the in-memory data collected in this session as well as discarding the data file.

exclude(regex, which='exclude')

Exclude source lines from execution consideration.

A number of lists of regular expressions are maintained. Each list selects lines that are treated differently during reporting.

which determines which list is modified. The “exclude” list selects lines that are not considered executable at all. The “partial” list indicates lines with branches that are not taken.

regex is a regular expression. The regex is added to the specified list. If any of the regexes in the list is found in a line, the line is marked for special treatment during reporting.

get_data()

Get the collected data.

Also warn about various problems collecting data.

Returns a coverage.CoverageData, the collected coverage data.

New in version 4.0.

get_exclude_list(which='exclude')

Return a list of excluded regex patterns.

which indicates which list is desired. See exclude() for the lists that are available, and their meaning.

get_option(option_name)

Get an option from the configuration.

option_name is a colon-separated string indicating the section and option name. For example, the branch option in the [run] section of the config file would be indicated with “run:branch”.

Returns the value of the option.

New in version 4.0.

html_report(morfs=None, directory=None, ignore_errors=None, omit=None, include=None, extra_css=None, title=None, skip_covered=None)

Generate an HTML report.

The HTML is written to directory. The file “index.html” is the overview starting point, with links to more detailed pages for individual modules.

extra_css is a path to a file of other CSS to apply on the page. It will be copied into the HTML directory.

title is a text string (not HTML) to use as the title of the HTML report.

See report() for other arguments.

Returns a float, the total percentage covered.

load()

Load previously-collected coverage data from the data file.

report(morfs=None, show_missing=None, ignore_errors=None, file=None, omit=None, include=None, skip_covered=None)

Write a summary report to file.

Each module in morfs is listed, with counts of statements, executed statements, missing statements, and a list of lines missed.

include is a list of file name patterns. Files that match will be included in the report. Files matching omit will not be included in the report.

If skip_covered is True, don’t report on files with 100% coverage.

Returns a float, the total percentage covered.

save()

Save the collected coverage data to the data file.

set_option(option_name, value)

Set an option in the configuration.

option_name is a colon-separated string indicating the section and option name. For example, the branch option in the [run] section of the config file would be indicated with "run:branch".

value is the new value for the option. This should be a Python value where appropriate. For example, use True for booleans, not the string "True".

As an example, calling:

cov.set_option("run:branch", True)

has the same effect as this configuration file:

[run]
branch = True

New in version 4.0.

start()

Start measuring code coverage.

Coverage measurement only occurs in functions called after start() is invoked. Statements in the same scope as start() won’t be measured.

Once you invoke start(), you must also call stop() eventually, or your process might not shut down cleanly.

stop()

Stop measuring code coverage.

xml_report(morfs=None, outfile=None, ignore_errors=None, omit=None, include=None)

Generate an XML report of coverage results.

The report is compatible with Cobertura reports.

Each module in morfs is included in the report. outfile is the path to write the file to, “-” will write to stdout.

See report() for other arguments.

Returns a float, the total percentage covered.

Starting coverage.py automatically

This function is used to start coverage measurement automatically when Python starts. See Measuring sub-processes for details.

coverage.process_startup()

Call this at Python start-up to perhaps measure coverage.

If the environment variable COVERAGE_PROCESS_START is defined, coverage measurement is started. The value of the variable is the config file to use.

There are two ways to configure your Python installation to invoke this function when Python starts:

  1. Create or append to sitecustomize.py to add these lines:

    import coverage
    coverage.process_startup()
    
  2. Create a .pth file in your Python installation containing:

    import coverage; coverage.process_startup()
    

Returns the Coverage instance that was started, or None if it was not started by this call.