diff --git a/src/emqx_config.erl b/src/emqx_config.erl
index 3d4c33369..bef0302f6 100644
--- a/src/emqx_config.erl
+++ b/src/emqx_config.erl
@@ -14,33 +14,12 @@
 %% limitations under the License.
 %%--------------------------------------------------------------------
 
-%% @doc Hot Configuration
-%%
-%% TODO: How to persist the configuration?
-%%
-%% 1. Store in mnesia database?
-%% 2. Store in dets?
-%% 3. Store in data/app.config?
-
 -module(emqx_config).
 
--export([populate/1]).
-
--export([ read/1
-        , write/2
-        , dump/2
-        , reload/1
-        ]).
-
--export([ set/3
-        , get/2
-        , get/3
-        , get_env/1
+-export([ get_env/1
         , get_env/2
         ]).
 
--type(env() :: {atom(), term()}).
-
 -define(APP, emqx).
 
 %% @doc Get environment
@@ -51,91 +30,3 @@ get_env(Key) ->
 -spec(get_env(Key :: atom(), Default :: term()) -> term()).
 get_env(Key, Default) ->
     application:get_env(?APP, Key, Default).
-
-%% TODO:
-populate(_App) ->
-    ok.
-
-%% @doc Read the configuration of an application.
--spec(read(atom()) -> {ok, list(env())} | {error, term()}).
-read(App) ->
-    %% TODO:
-    %% 1. Read the app.conf from etc folder
-    %% 2. Cuttlefish to read the conf
-    %% 3. Return the terms and schema
-    % {error, unsupported}.
-    {ok, read_(App)}.
-
-%% @doc Reload configuration of an application.
--spec(reload(atom()) -> ok | {error, term()}).
-reload(_App) ->
-    %% TODO
-    %% 1. Read the app.conf from etc folder
-    %% 2. Cuttlefish to generate config terms.
-    %% 3. set/3 to apply the config
-    ok.
-
--spec(write(atom(), list(env())) -> ok | {error, term()}).
-write(_App, _Terms) -> ok.
-    % Configs = lists:map(fun({Key, Val}) ->
-    %     {cuttlefish_variable:tokenize(binary_to_list(Key)), binary_to_list(Val)}
-    % end, Terms),
-    % Path = lists:concat([code:priv_dir(App), "/", App, ".schema"]),
-    % Schema = cuttlefish_schema:files([Path]),
-    % case cuttlefish_generator:map(Schema, Configs) of
-    %     [{App, Configs1}] ->
-    %         emqx_cli_config:write_config(App, Configs),
-    %         lists:foreach(fun({Key, Val}) -> application:set_env(App, Key, Val) end, Configs1);
-    %     _ ->
-    %         error
-    % end.
-
--spec(dump(atom(), list(env())) -> ok | {error, term()}).
-dump(_App, _Terms) ->
-    %% TODO
-    ok.
-
--spec(set(atom(), list(), list()) -> ok).
-set(_App, _Par, _Val) -> ok.
-    % emqx_cli_config:run(["config",
-    %                         "set",
-    %                         lists:concat([Par, "=", Val]),
-    %                         lists:concat(["--app=", App])]).
-
--spec(get(atom(), list()) -> undefined | {ok, term()}).
-get(_App, _Par) -> error(no_impl).
-    % case emqx_cli_config:get_cfg(App, Par) of
-    %     undefined -> undefined;
-    %     Val -> {ok, Val}
-    % end.
-
--spec(get(atom(), list(), atom()) -> term()).
-get(_App, _Par, _Def) -> error(no_impl).
-    % emqx_cli_config:get_cfg(App, Par, Def).
-
-
-read_(_App) -> error(no_impl).
-    % Configs = emqx_cli_config:read_config(App),
-    % Path = lists:concat([code:priv_dir(App), "/", App, ".schema"]),
-    % case filelib:is_file(Path) of
-    %     false ->
-    %         [];
-    %     true ->
-    %         {_, Mappings, _} = cuttlefish_schema:files([Path]),
-    %         OptionalCfg = lists:foldl(fun(Map, Acc) ->
-    %             Key = cuttlefish_mapping:variable(Map),
-    %             case proplists:get_value(Key, Configs) of
-    %                 undefined ->
-    %                     [{cuttlefish_variable:format(Key), "", cuttlefish_mapping:doc(Map), false} | Acc];
-    %                 _ -> Acc
-    %             end
-    %         end, [], Mappings),
-    %         RequiredCfg = lists:foldl(fun({Key, Val}, Acc) ->
-    %             case lists:keyfind(Key, 2, Mappings) of
-    %                 false -> Acc;
-    %                 Map ->
-    %                     [{cuttlefish_variable:format(Key), Val, cuttlefish_mapping:doc(Map), true} | Acc]
-    %             end
-    %         end, [], Configs),
-    %         RequiredCfg ++ OptionalCfg
-    % end.
diff --git a/test/emqx_config_SUITE.erl b/test/emqx_config_SUITE.erl
new file mode 100644
index 000000000..5014e3ef3
--- /dev/null
+++ b/test/emqx_config_SUITE.erl
@@ -0,0 +1,39 @@
+%%--------------------------------------------------------------------
+%% Copyright (c) 2019 EMQ Technologies Co., Ltd. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%--------------------------------------------------------------------
+
+-module(emqx_config_SUITE).
+
+-compile(export_all).
+-compile(nowarn_export_all).
+
+-include_lib("eunit/include/eunit.hrl").
+
+all() -> emqx_ct:all(?MODULE).
+
+init_per_suite(Config) ->
+    emqx_ct_helpers:start_apps([]),
+    Config.
+
+end_per_suite(_Config) ->
+    emqx_ct_helpers:stop_apps([]).
+
+t_get_env(_) ->
+    ?assertEqual(undefined, emqx_config:get_env(undefined_key)),
+    ?assertEqual(default_value, emqx_config:get_env(undefined_key, default_value)),
+    application:set_env(emqx, undefined_key, hello),
+    ?assertEqual(hello, emqx_config:get_env(undefined_key)),
+    ?assertEqual(hello, emqx_config:get_env(undefined_key, default_value)),
+    application:unset_env(emqx, undefined_key).
\ No newline at end of file