chore(test): improve coverage

apps/emqx/src/emqx.erl

@@ -189,8 +189,13 @@ get_config(KeyPath) ->
 
 -spec get_config(emqx_utils_maps:config_key_path(), term()) -> term().
 get_config(KeyPath, Default) ->
-    KeyPath1 = emqx_config:ensure_atom_conf_path(KeyPath, {return, Default}),
-    emqx_config:get(KeyPath1, Default).
+    try
+        KeyPath1 = emqx_config:ensure_atom_conf_path(KeyPath, {raise_error, config_not_found}),
+        emqx_config:get(KeyPath1, Default)
+    catch
+        error:config_not_found ->
+            Default
+    end.
 
 -spec get_raw_config(emqx_utils_maps:config_key_path()) -> term().
 get_raw_config(KeyPath) ->

apps/emqx/test/emqx_SUITE.erl

@@ -156,6 +156,19 @@ t_cluster_nodes(_) ->
     ?assertEqual(Expected, emqx:cluster_nodes(cores)),
     ?assertEqual([], emqx:cluster_nodes(stopped)).
 
+t_get_config(_) ->
+    ?assertEqual(false, emqx:get_config([overload_protection, enable])),
+    ?assertEqual(false, emqx:get_config(["overload_protection", <<"enable">>])).
+
+t_get_config_default_1(_) ->
+    ?assertEqual(false, emqx:get_config([overload_protection, enable], undefined)),
+    ?assertEqual(false, emqx:get_config(["overload_protection", <<"enable">>], undefined)).
+
+t_get_config_default_2(_) ->
+    AtomPathRes = emqx:get_config([overload_protection, <<"_!no_@exist_">>], undefined),
+    NonAtomPathRes = emqx:get_config(["doesnotexist", <<"db_backend">>], undefined),
+    ?assertEqual(undefined, NonAtomPathRes),
+    ?assertEqual(undefined, AtomPathRes).
 %%--------------------------------------------------------------------
 %% Hook fun
 %%--------------------------------------------------------------------