Allow single test spec in ct_opts

The option {spec,Specs} is allowed in ct_opts, but
rebar_prv_common_test:test_dirs did not take into account that Specs
could also be a string only, i.e. not a list of strings.

src/rebar_prv_common_test.erl

@@ -431,18 +431,21 @@ test_dirs(State, Apps, Opts) ->
                     set_compile_dirs(State, Apps, join(Suites, Dir));
                 {_Suites, _Dirs}    -> {error, "Only a single directory may be specified when specifying suites"}
             end;
-        Specs0 ->
-            case get_dirs_from_specs(Specs0) of
-                {ok,{Specs,SuiteDirs}} ->
-                    {State1,Apps1} = set_compile_dirs1(State, Apps,
-                                                       {dir, SuiteDirs}),
-                    {State2,Apps2} = set_compile_dirs1(State1, Apps1,
-                                                       {spec, Specs}),
-                    [maybe_copy_spec(State2,Apps2,S) || S <- Specs],
-                    {ok, rebar_state:project_apps(State2, Apps2)};
-                Error ->
-                    Error
-            end
+        Spec when is_integer(hd(Spec)) ->
+            spec_test_dirs(State, Apps, [Spec]);
+        Specs ->
+            spec_test_dirs(State, Apps, Specs)
+    end.
+
+spec_test_dirs(State, Apps, Specs0) ->
+    case get_dirs_from_specs(Specs0) of
+        {ok,{Specs,SuiteDirs}} ->
+            {State1,Apps1} = set_compile_dirs1(State, Apps, {dir, SuiteDirs}),
+            {State2,Apps2} = set_compile_dirs1(State1, Apps1, {spec, Specs}),
+            [maybe_copy_spec(State2,Apps2,S) || S <- Specs],
+            {ok, rebar_state:project_apps(State2, Apps2)};
+        Error ->
+            Error
     end.
 
 join(Suite, Dir) when is_integer(hd(Suite)) ->

test/rebar_ct_SUITE.erl

@@ -55,7 +55,8 @@
          testspec/1,
          testspec_at_root/1,
          testspec_parse_error/1,
-         cmd_vs_cfg_opts/1]).
+         cmd_vs_cfg_opts/1,
+         single_testspec_in_ct_opts/1]).
 
 -include_lib("eunit/include/eunit.hrl").
 -include_lib("common_test/include/ct.hrl").
@@ -75,7 +76,8 @@ all() -> [{group, basic_app},
           testspec,
           testspec_at_root,
           testspec_parse_error,
-          cmd_vs_cfg_opts].
+          cmd_vs_cfg_opts,
+          single_testspec_in_ct_opts].
 
 groups() -> [{basic_app, [], [basic_app_default_dirs,
                               basic_app_default_beams,
@@ -1548,6 +1550,41 @@ cmd_vs_cfg_opts(Config) ->
 
     ok.
 
+single_testspec_in_ct_opts(Config) ->
+    C = rebar_test_utils:init_rebar_state(Config, "ct_testspec_"),
+
+    AppDir = ?config(apps, C),
+
+    Name = rebar_test_utils:create_random_name("ct_testspec_"),
+    Vsn = rebar_test_utils:create_random_vsn(),
+    rebar_test_utils:create_app(AppDir, Name, Vsn, [kernel, stdlib]),
+    Spec = filename:join([AppDir, "test", "some.spec"]),
+    ok = filelib:ensure_dir(Spec),
+    ok = file:write_file(Spec, "{suites,\".\",all}.\n"),
+
+    {ok,Wd} = file:get_cwd(),
+    ok = file:set_cwd(AppDir),
+
+    RebarConfig = [{ct_opts, [{spec,"test/some.spec"}]}],
+
+    {ok, State} = rebar_test_utils:run_and_check(C, RebarConfig, ["as", "test", "lock"], return),
+
+    Providers = rebar_state:providers(State),
+    Namespace = rebar_state:namespace(State),
+    CommandProvider = providers:get_provider(ct, Providers, Namespace),
+    GetOptSpec = providers:opts(CommandProvider),
+
+    %% Testspec in "test" directory
+    {ok, GetOptResult1} = getopt:parse(GetOptSpec, []),
+    State1 = rebar_state:command_parsed_args(State, GetOptResult1),
+    Tests1 = rebar_prv_common_test:prepare_tests(State1),
+    {ok, T1} = Tests1,
+    "test/some.spec" = proplists:get_value(spec,T1),
+    {ok, _NewState} = rebar_prv_common_test:compile(State1, Tests1),
+
+    ok = file:set_cwd(Wd),
+    ok.
+
 %% helper for generating test data
 test_suite(Name) ->
     io_lib:format("-module(~ts_SUITE).\n"