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Diffstat (limited to 'lib/common_test/doc/src/config_file_chapter.xml')
| -rw-r--r-- | lib/common_test/doc/src/config_file_chapter.xml | 252 |
1 files changed, 238 insertions, 14 deletions
diff --git a/lib/common_test/doc/src/config_file_chapter.xml b/lib/common_test/doc/src/config_file_chapter.xml index a22a5270c1..850bc74e19 100644 --- a/lib/common_test/doc/src/config_file_chapter.xml +++ b/lib/common_test/doc/src/config_file_chapter.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2004</year><year>2009</year> + <year>2004</year><year>2010</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -13,12 +13,12 @@ compliance with the License. You should have received a copy of the Erlang Public License along with this software. If not, it can be retrieved online at http://www.erlang.org/. - + Software distributed under the License is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for the specific language governing rights and limitations under the License. - + </legalnotice> <title>Config Files</title> @@ -180,7 +180,126 @@ </section> <section> - <title>Examples</title> + <title>User specific configuration data formats</title> + + <p>It is possible for the user to specify configuration data on a + different format than key-value tuples in a text file, as described + so far. The data can e.g. be read from arbitrary files, fetched from + the web over http, or requested from a user specific process. + To support this, Common Test provides a callback module plugin + mechanism to handle configuration data.</p> + + <section> + <title>Default callback modules for handling configuration data</title> + <p>The Common Test application includes default callback modules + for handling configuration data specified in standard config files + (see above) and in xml files:</p> + <list> + <item> + <c>ct_config_plain</c> - for reading configuration files with + key-value tuples (standard format). This handler will be used to + parse configuration files if no user callback is specified. + </item> + <item> + <c>ct_config_xml</c> - for reading configuration data from XML + files. + </item> + </list> + </section> + + <section> + <title>Using XML configuration files</title> + <p>This is an example of an XML configuration file:</p> + <pre><![CDATA[ +<config> + <ftp_host> + <ftp>"targethost"</ftp> + <username>"tester"</username> + <password>"letmein"</password> + </ftp_host> + <lm_directory>"/test/loadmodules"</lm_directory> +</config>]]></pre> + + <p>This configuration file, once read, will produce the same configuration + variables as the following text file:</p> + <pre> +{ftp_host, [{ftp,"targethost"}, + {username,"tester"}, + {password,"letmein"}]}. + +{lm_directory, "/test/loadmodules"}.</pre> + </section> + + <section> + <title>How to implement a user specific handler</title> + + <p>The user specific handler can be written to handle special + configuration file formats. The parameter can be either file + name(s) or configuration string(s) (the empty list is valid).</p> + + <p>The callback module implementing the handler is responsible for + checking correctness of configuration strings.</p> + + <p>To perform validation of the configuration strings, the callback module + should have the following function exported:</p> + + <p><c>Callback:check_parameter/1</c></p> + <p>The input argument will be passed from Common Test, as defined in the test + specification or given as an option to <c>run_test</c>.</p> + + <p>The return value should be any of the following values indicating if given + configuration parameter is valid:</p> + <list> + <item> + <c>{ok, {file, FileName}}</c> - parameter is a file name and + the file exists, + </item> + <item> + <c>{ok, {config, ConfigString}}</c> - parameter is a config string + and it is correct, + </item> + <item> + <c>{error, {nofile, FileName}}</c> - there is no file with the given + name in the current directory, + </item> + <item> + <c>{error, {wrong_config, ConfigString}}</c> - the configuration string + is wrong. + </item> + </list> + + <p>To perform reading of configuration data - initially before the tests + start, or as a result of data being reloaded during test execution - + the following function should be exported from the callback module:</p> + + <p><c>Callback:read_config/1</c></p> + + <p>The input argument is the same as for the <c>check_parameter/1</c> function.</p> + <p>The return value should be either:</p> + + <list> + <item> + <c>{ok, Config}</c> - if the configuration variables are read successfully, + </item> + <item> + <c>{error, Error, ErrorDetails}</c> - if the callback module fails to + proceed with the given configuration parameters. + </item> + </list> + <p><c>Config</c> is the proper Erlang key-value list, with possible + key-value sublists as values, like for the configuration file + example above:</p> + + <pre> + [{ftp_host, [{ftp, "targethost"}, {username, "tester"}, {password, "letmein"}]}, + {lm_directory, "/test/loadmodules"}]</pre> + + </section> + + </section> + + <section> + <title>Examples of configuration data handling</title> <p>A config file for using the FTP client to access files on a remote host could look like this:</p> @@ -188,28 +307,33 @@ <pre> {ftp_host, [{ftp,"targethost"}, {username,"tester"}, - {password,"letmein"}]}. + {password,"letmein"}]}. {lm_directory, "/test/loadmodules"}.</pre> - <p>Example of how to assert that the configuration data is available and + + <p>The XML version shown in the chapter above can also be used, but it should be + explicitly specified that the <c>ct_config_xml</c> callback module is to be + used by Common Test.</p> + + <p>Example of how to assert that the configuration data is available and use it for an FTP session:</p> <pre> init_per_testcase(ftptest, Config) -> {ok,_} = ct_ftp:open(ftp), - Config. + Config. end_per_testcase(ftptest, _Config) -> ct_ftp:close(ftp). ftptest() -> [{require,ftp,ftp_host}, - {require,lm_directory}]. + {require,lm_directory}]. ftptest(Config) -> - Remote = filename:join(ct:get_config(lm_directory), "loadmodX"), + Remote = filename:join(ct:get_config(lm_directory), "loadmodX"), Local = filename:join(?config(priv_dir,Config), "loadmodule"), ok = ct_ftp:recv(ftp, Remote, Local), - ...</pre> + ...</pre> <p>An example of how the above functions could be rewritten if necessary to open multiple connections to the FTP server:</p> @@ -217,7 +341,7 @@ init_per_testcase(ftptest, Config) -> {ok,Handle1} = ct_ftp:open(ftp_host), {ok,Handle2} = ct_ftp:open(ftp_host), - [{ftp_handles,[Handle1,Handle2]} | Config]. + [{ftp_handles,[Handle1,Handle2]} | Config]. end_per_testcase(ftptest, Config) -> lists:foreach(fun(Handle) -> ct_ftp:close(Handle) end, @@ -225,17 +349,117 @@ ftptest() -> [{require,ftp_host}, - {require,lm_directory}]. + {require,lm_directory}]. ftptest(Config) -> - Remote = filename:join(ct:get_config(lm_directory), "loadmodX"), + Remote = filename:join(ct:get_config(lm_directory), "loadmodX"), Local = filename:join(?config(priv_dir,Config), "loadmodule"), [Handle | MoreHandles] = ?config(ftp_handles,Config), ok = ct_ftp:recv(Handle, Remote, Local), - ...</pre> + ...</pre> </section> + <section> + <title>Example of user specific configuration handler</title> + <p>A simple configuration handling driver which will ask an external server for + configuration data can be implemented this way:</p> + <pre> +-module(config_driver). +-export([read_config/1, check_parameter/1]). + +read_config(ServerName)-> + ServerModule = list_to_atom(ServerName), + ServerModule:start(), + ServerModule:get_config(). + +check_parameter(ServerName)-> + ServerModule = list_to_atom(ServerName), + case code:is_loaded(ServerModule) of + {file, _}-> + {ok, {config, ServerName}}; + false-> + case code:load_file(ServerModule) of + {module, ServerModule}-> + {ok, {config, ServerName}}; + {error, nofile}-> + {error, {wrong_config, "File not found: " ++ ServerName ++ ".beam"}} + end + end.</pre> + + <p>The configuration string for this driver may be "config_server", if the + config_server.erl module below is compiled and exists in the code path + during test execution:</p> + <pre> +-module(config_server). +-export([start/0, stop/0, init/1, get_config/0, loop/0]). + +-define(REGISTERED_NAME, ct_test_config_server). + +start()-> + case whereis(?REGISTERED_NAME) of + undefined-> + spawn(?MODULE, init, [?REGISTERED_NAME]), + wait(); + _Pid-> + ok + end, + ?REGISTERED_NAME. + +init(Name)-> + register(Name, self()), + loop(). + +get_config()-> + call(self(), get_config). + +stop()-> + call(self(), stop). + +call(Client, Request)-> + case whereis(?REGISTERED_NAME) of + undefined-> + {error, not_started, Request}; + Pid-> + Pid ! {Client, Request}, + receive + Reply-> + {ok, Reply} + after 4000-> + {error, timeout, Request} + end + end. + +loop()-> + receive + {Pid, stop}-> + Pid ! ok; + {Pid, get_config}-> + {D,T} = erlang:localtime(), + Pid ! + [{localtime, [{date, D}, {time, T}]}, + {node, erlang:node()}, + {now, erlang:now()}, + {config_server_pid, self()}, + {config_server_vsn, ?vsn}], + ?MODULE:loop() + end. + +wait()-> + case whereis(?REGISTERED_NAME) of + undefined-> + wait(); + _Pid-> + ok + end.</pre> + + <p>In this example, the handler also provides the ability to dynamically reload + configuration variables. If <c>ct:reload_config(localtime)</c> is called from + the test case function, all variables loaded with <c>config_driver:read_config/1</c> + will be updated with their latest values, and the new value for variable + <c>localtime</c> will be returned.</p> + </section> + </chapter> |