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cover - report coverage statistics


version 1.26


 cover -test

 cover -report html_basic


Report coverage statistics in a variety of formats.

The summary option produces a short textual summary. Other reports are available by using the report option.

The following reports are currently available:

 html        - detailed HTML reports  (default)
 html_basic  - detailed HTML reports with syntax highlighting
 text        - detailed textual summary
 compilation - output in a format similar to Perl errors
 json        - output in a JSON format
 vim         - show coverage information in vim gutter


The following command line options are supported:

 -h -help              - show help
 -i -info              - show documentation
 -v -version           - show version

 -silent               - don't print informational messages (default off)
 -summary              - give summary report                (default on)
 -report report_format - report format                      (default html)
 -outputdir dir        - directory for output               (default given db)
 -launch               - launch report in viewer (if avail) (default off)

 -select filename      - only report on the file            (default all)
 -ignore filename      - don't report on the file           (default none)
 -select_re RE         - append to REs of files to select   (default none)
 -ignore_re RE         - append to REs of files to ignore   (default none)
 -write [db]           - write the merged database          (default off)
 -delete               - drop database(s)                   (default off)
 -dump_db              - dump database(s) (for debugging)   (default off)

 -coverage criterion   - report on criterion  (default all available)

 -test                 - drop database(s) and run make test (default off)
 -gcov                 - run gcov to cover XS code     (default on if using gcc)
 -make make_prog       - use the given 'make' program for 'make test'

 -add_uncoverable_point    string
 -delete_uncoverable_point string
 -uncoverable_file         file

 other options specific to the report format

 coverage_database [coverage_database ...]


The following -report options are available in the core module. Other reports may be available if they've been installed from external packages.

html|html_minimal (default)

HTML reporting. Percentage thresholds are colour-coded and configurable via -report_c0 <integer>, -report_c1 <integer> and -report_c2 <integer>.:

    0%      75%      90%      100%
    |   ..   |   ..   |   ..   |
       <c0      <c1      <c2   c3
       red     yellow   orange green

HTML reporting with syntax highlighting if PPI::HTML or Perl::Tidy module is detected. Like html|html_minimal reporting, percentage thresholds are colour-coded and configurable.


Plain text reporting.


A textual report in a format similar to that output by Perl itself such that the report may be used by your editor or other reporting tools to show where coverage is missing.


A report in JSON format.


A report suitable for use with the vim editor to show coverage data in the sign column.


Any number of coverage databases may be specified on the command line. These databases will be merged and the reports will be based on the merged information. If no databases are specified the default database (cover_db) will be used.

The -write option will write out the merged database. If no name is given for the new database, the first database read in will be overwritten. When this option is used no reports are generated by default.

Specify the -select, -select_re, -ignore, and -ignore_re options to report on specific files. -select and -ignore are interpreted as shell globs; -select_re and -ignore_re are interpreted as regular expressions.

Specify -coverage options to report on specific criteria. By default all available information on all criteria in all files will be reported. Available coverage options are statement, branch, condition, subroutine, pod, and default (which equates to all available options). However, if you know you only want coverage information for certain criteria it is better to only collect data for those criteria in the first place by specifying them at that point. This will make the data collection and reporting processes faster and less memory intensive. See the documentation for Devel::Cover for more information.

If you want all *except* some criteria, then you can say something like '-coverage default,-pod'.

The -test option will delete the databases and run your tests to generate new coverage data before reporting on it. Devel::Cover knows how to work with standard Perl Makefiles as well as Module::Build based distributions. For detailed instructions see the documentation for ExtUtils::MakeMaker at or for Module::Build at both of which come as standard in recent Perl distributions.

The -gcov option will try to run gcov on any XS code. This requires that you are using gcc of course. If you are using the -test option will be turned on by default.


The following exit values are returned:

0 All operations were completed successfully.

>0 An error occurred.

With the -test option the exit status of the underlying test run is returned.




Did I mention that this is alpha code?

See the BUGS file.


Copyright 2001-2017, Paul Johnson (

This software is free. It is licensed under the same terms as Perl itself.

The latest version of this software should be available from my homepage:

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