[t] rewrite config loading test using blackbox

t/configuration-loading-boot-with-config.t

@@ -1,14 +1,10 @@
 use lib 't';
-use TestAPIcast 'no_plan';
+use TestAPIcastBlackbox 'no_plan';
 
-$ENV{TEST_NGINX_HTTP_CONFIG} = "$TestAPIcast::path/http.d/init.conf";
 $ENV{APICAST_CONFIGURATION_LOADER} = 'boot';
-$ENV{THREESCALE_CONFIG_FILE} = 't/servroot/html/config.json';
 
 env_to_nginx(
     'APICAST_CONFIGURATION_LOADER',
-    'TEST_NGINX_APICAST_PATH',
-    'THREESCALE_CONFIG_FILE'
 );
 
 log_level('warn');
@@ -18,27 +14,19 @@ __DATA__
 
 === TEST 1: require configuration file to exist
 should exit when the config file is missing
---- http_config
-  include $TEST_NGINX_HTTP_CONFIG;
-  lua_package_path "$TEST_NGINX_LUA_PATH";
---- config
 --- must_die
---- request
-GET
+--- configuration_file
+t/servroot/html/config.json
 --- error_log
 config.json: No such file or directory
 --- user_files
 >>> wrong.json
 
 === TEST 2: require valid json file
 should exit when the file has invalid json
---- http_config
-  include $TEST_NGINX_HTTP_CONFIG;
-  lua_package_path "$TEST_NGINX_LUA_PATH";
---- config
 --- must_die
---- request
-GET
+--- configuration_file
+t/servroot/html/config.json
 --- error_log
 Expected value but found invalid token at character 1
 --- user_files
@@ -47,12 +35,11 @@ not valid json
 
 === TEST 3: empty json file
 should continue as empty json is enough
---- http_config
-  include $TEST_NGINX_HTTP_CONFIG;
-  lua_package_path "$TEST_NGINX_LUA_PATH";
---- config
+--- configuration_file
+t/servroot/html/config.json
 --- request
 GET
+--- error_code: 404
 --- user_files
 >>> config.json
 {}