Rebar3_uncovered - Plug-in to show uncovered lines

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Is it a new movie documentary about Rebar and its secret development practices? :detective: No, it’s a plug-in! :puzzle_piece: :wink:

rebar3_uncovered

A Rebar 3 plugin that reports on uncovered lines from tests. Run it after
rebar3 eunit or rebar3 ct to see which lines your tests missed. Use --git
to narrow the report to lines changed since the last commit.

screenshot
screenshot3260×1864 205 KB

A machine-readable format is also available for script / CI / LLM consumption.
Prefix with QUIET=1 to suppress Rebar’s own log messages:

$ QUIET=1 rebar3 uncovered --git --format=raw --context=0 --counts=false
src/gaffer_queue.erl:141             _ = gaffer_hooks:with_hooks(
src/gaffer_queue.erl:142                 Hooks, [gaffer, queue, delete], Name, fun(N) -> N end
src/gaffer_queue.erl:144             ok = gaffer_sup:stop_queue(gaffer_queue_sup:pid(Name)),
src/gaffer_queue.erl:145             persistent_term:erase({gaffer_queue, Name})
src/gaffer_queue.erl:151         {error, not_found} -> ok

Installation

Add the plugin to your project’s rebar.config:

{project_plugins, [rebar3_uncovered]}.

To install it globally for all projects, add it to
~/.config/rebar3/rebar.config:

{plugins, [rebar3_uncovered]}.

Usage

rebar3 uncovered [options] [-- path ...]
rebar3 help uncovered

Positional arguments after -- are used as file or directory filters.

Options

  • --help, -h

    Show usage information and available options.

  • --git, -g

    Filter uncovered lines to only those changed in the current git diff.
    Disabled by default.

  • --git-scope

    Which part of the git diff to consider. Only has effect when --git is
    enabled.

    • all (default) — both staged and unstaged changes
    • staged — only changes added to the index
    • unstaged — only working tree changes

  • --coverage

    Which coverage data to use.

    • aggregate (default) — combine all test suites
    • eunit — only EUnit coverage data
    • ct — only Common Test coverage data

  • --format, -f

    Output format.

    • human (default) — color-coded table with line numbers, coverage counts,
      and source context
    • raw — one line per uncovered line in a grep-like format suitable for
      scripts, CI, or LLM consumption. Set the environment variable QUIET=1 to
      suppress Rebar’s own log messages for clean output

  • --context, -C

    Number of covered lines to show around each uncovered line for context. Only
    applies to human format.

    • <integer> (default: 2) — number of context lines to show
    • 0 — show only uncovered lines
    • all — show the entire function

  • --counts

    Show how many times each line was executed. Use --counts false to hide the
    counts column. Enabled by default.

  • --color

    Color output. Respects the NO_COLOR environment variable.

    • auto (default) — enable color when output is a terminal
    • always — force color on
    • never — disable color

License

This project uses the MIT License.

Links

rebar3_uncovered is available on Hex and on GitHub:

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