Support minimal coverage validation in tests

Adds an option (-m, --min_coverage, or {cover_opts, {min_coverage,X}})
to the 'cover' command, where the value is an integer between 0 and 100.

If the total coverage during the analysis is below the value received,
the command will fail with output like:

    ===> Requiring 64% coverage to pass. Only 62% obtained

If the rate is correct, the command silently passes as it currently
does.

This feature allows to enforce code coverage standards in a project if
desired.

1 files changed, 48 insertions, 2 deletions

diff --git a/test/rebar_cover_SUITE.erl b/test/rebar_cover_SUITE.erl
index cc06c95..2918123 100644
--- a/test/rebar_cover_SUITE.erl
+++ b/test/rebar_cover_SUITE.erl
@@ -14,7 +14,9 @@
          flag_verbose/1,
          config_verbose/1,
          excl_mods_and_apps/1,
-         coverdata_is_reset_on_write/1]).
+         coverdata_is_reset_on_write/1,
+         flag_min_coverage/1,
+         config_min_coverage/1]).
 
 -include_lib("common_test/include/ct.hrl").
 -include_lib("eunit/include/eunit.hrl").
@@ -38,7 +40,8 @@ all() ->
      root_extra_src_dirs,
      index_written,
      flag_verbose, config_verbose,
-     excl_mods_and_apps, coverdata_is_reset_on_write].
+     excl_mods_and_apps, coverdata_is_reset_on_write,
+     flag_min_coverage, config_min_coverage].
 
 flag_coverdata_written(Config) ->
     AppDir = ?config(apps, Config),
@@ -257,3 +260,46 @@ coverdata_is_reset_on_write(Config) ->
     Res = lists:map(fun(M) -> cover:analyse(M) end, cover:modules()),
     Ok = lists:foldl(fun({ok, R}, Acc) -> R ++ Acc end, [], Res),
     [] = lists:filter(fun({_, {0,_}}) -> false; (_) -> true end, Ok).
+
+flag_min_coverage(Config) ->
+    AppDir = ?config(apps, Config),
+
+    Name = rebar_test_utils:create_random_name("min_cover_"),
+    Vsn = rebar_test_utils:create_random_vsn(),
+    rebar_test_utils:create_eunit_app(AppDir, Name, Vsn, [kernel, stdlib]),
+
+    RebarConfig = [{erl_opts, [{d, some_define}]}],
+    ?assertMatch({ok, _},
+                 rebar_test_utils:run_and_check(
+                   Config, RebarConfig,
+                   ["do", "eunit", "--cover", ",", "cover", "--min_coverage=5"],
+                   return)),
+
+    ?assertMatch({error,{rebar_prv_cover,{min_coverage_failed,{65,_}}}},
+                 rebar_test_utils:run_and_check(
+                   Config, RebarConfig,
+                   ["do", "eunit", "--cover", ",", "cover", "--min_coverage=65"],
+                   return)),
+    ok.
+
+config_min_coverage(Config) ->
+    AppDir = ?config(apps, Config),
+
+    Name = rebar_test_utils:create_random_name("cover_"),
+    Vsn = rebar_test_utils:create_random_vsn(),
+    rebar_test_utils:create_eunit_app(AppDir, Name, Vsn, [kernel, stdlib]),
+
+    RebarConfig1 = [{erl_opts, [{d, some_define}]}, {cover_opts, [{min_coverage,5}]}],
+    ?assertMatch({ok, _},
+                 rebar_test_utils:run_and_check(
+                   Config, RebarConfig1,
+                   ["do", "eunit", "--cover", ",", "cover"],
+                   return)),
+
+    RebarConfig2 = [{erl_opts, [{d, some_define}]}, {cover_opts, [{min_coverage,65}]}],
+    ?assertMatch({error,{rebar_prv_cover,{min_coverage_failed,{65,_}}}},
+                 rebar_test_utils:run_and_check(
+                   Config, RebarConfig2,
+                   ["do", "eunit", "--cover", ",", "cover"],
+                   return)),
+    ok.