introduce transform callback. fixes #53

README.md

@@ -179,12 +179,17 @@ bin/katt --json base_url=http://httpbin.org my_name=Joe your_name=Mike -- doc/ex
     * `validate` to be called with `expected`, `actual`, `params`, `callbacks`
     * `progress` to be called with `transaction_result`
     * `text_diff` to be called with `text`, `text`
+    * `transform` to be called with `id`, `katt_request` or `{katt_response, actual_response}`, `params`, `callbacks`
 
 A request can also be configured via HTTP request headers:
 
 * `x-katt-description` would take precedence over the transaction's description
 * `x-katt-request-timeout` would take precedence over the `request_timeout` param
 * `x-katt-request-sleep` would delay the request for a specific amount of milliseconds
+* `x-katt-transform` would call the `tranform` callback with it's value as `id`
+
+A response can also be configured via HTTP response headers:
+* `x-katt-transform` would call the `tranform` callback with it's value as `id`
 
 ### If you would like to convert a HAR file to an APIB file
 

src/katt.erl

@@ -129,6 +129,7 @@ make_callbacks(Callbacks) ->
                             , {recall, ?DEFAULT_RECALL_FUN}
                             , {request, ?DEFAULT_REQUEST_FUN}
                             , {text_diff, ?DEFAULT_TEXT_DIFF_FUN}
+                            , {transform, ?DEFAULT_TRANSFORM_FUN}
                             , {validate, ?DEFAULT_VALIDATE_FUN}
                             ], Callbacks).
 
@@ -234,10 +235,10 @@ run_transactions( From
   Req = Req0#katt_request{headers = Hdrs},
   From ! {progress, run_transaction, Description},
   Request = make_katt_request(Req, Params, Callbacks),
-  ExpectedResponse = make_katt_response(Res, Params, Callbacks),
   RequestFun = proplists:get_value(request, Callbacks),
   ValidateFun = proplists:get_value(validate, Callbacks),
   ActualResponse = RequestFun(Request, Params, Callbacks),
+  ExpectedResponse = make_katt_response(ActualResponse, Res, Params, Callbacks),
   ValidationResult = ValidateFun( ExpectedResponse
                                 , ActualResponse
                                 , Params
@@ -270,7 +271,7 @@ run_transactions( From
       {Params, {Count + 1, [Result|Results]}}
   end.
 
-make_katt_request( #katt_request{headers=Hdrs0, url=Url0, body=Body0} = Req
+make_katt_request( #katt_request{url=Url0, headers=Hdrs0, body=Body0} = Req0
                  , Params
                  , Callbacks
                  ) ->
@@ -284,12 +285,14 @@ make_katt_request( #katt_request{headers=Hdrs0, url=Url0, body=Body0} = Req
   Url = make_request_url(Url1, Params),
   Hdrs = RecallFun(headers, Hdrs0, Params, Callbacks),
   [Hdrs, Body] = RecallFun(body, [Hdrs, Body0], Params, Callbacks),
-  Req#katt_request{ url = Url
-                  , headers = Hdrs
-                  , body = Body
-                  }.
+  Req = Req0#katt_request{ url = Url
+                         , headers = Hdrs
+                         , body = Body
+                         },
+  maybe_transform_request(Req, Params, Callbacks).
 
-make_katt_response( #katt_response{headers=Hdrs0, body=Body0} = Res
+make_katt_response( ActualResponse
+                  , #katt_response{headers=Hdrs0, body=Body0} = Res0
                   , Params
                   , Callbacks
                   ) ->
@@ -298,10 +301,11 @@ make_katt_response( #katt_response{headers=Hdrs0, body=Body0} = Res
   Hdrs = RecallFun(headers, Hdrs0, Params, Callbacks),
   [Hdrs, Body] = RecallFun(body, [Hdrs, Body0], Params, Callbacks),
   ParsedBody = ParseFun(Hdrs, Body, Params, Callbacks),
-  Res#katt_response{ headers = Hdrs
-                   , body = Body
-                   , parsed_body = ParsedBody
-                   }.
+  Res = Res0#katt_response{ headers = Hdrs
+                          , body = Body
+                          , parsed_body = ParsedBody
+                          },
+  maybe_transform_response(Res, Params, Callbacks, ActualResponse).
 
 -spec make_request_url( string()
                       , params()
@@ -320,8 +324,31 @@ make_request_url(Path, Params) ->
               , Path
               ], "").
 
-
 make_host(?PROTOCOL_HTTP, Hostname, 80) -> Hostname;
 make_host(?PROTOCOL_HTTPS, Hostname, 443) -> Hostname;
 make_host(_Proto, Hostname, Port) ->
   Hostname ++ ":" ++ katt_util:to_list(Port).
+
+maybe_transform_request(Req0, Params, Callbacks) ->
+  Hdrs0 = Req0#katt_request.headers,
+  case proplists:get_value("x-katt-transform", Hdrs0) of
+    undefined ->
+      Req0;
+    TransformId ->
+      TransformFun = proplists:get_value(transform, Callbacks),
+      Hdrs = proplists:delete("x-katt-transform", Hdrs0),
+      Req = Req0#katt_request{headers = Hdrs},
+      TransformFun(TransformId, Req, Params, Callbacks)
+  end.
+
+maybe_transform_response(Res0, Params, Callbacks, ActualResponse) ->
+  Hdrs0 = Res0#katt_response.headers,
+  case proplists:get_value("x-katt-transform", Hdrs0) of
+    undefined ->
+      Res0;
+    TransformId ->
+      TransformFun = proplists:get_value(transform, Callbacks),
+      Hdrs = proplists:delete("x-katt-transform", Hdrs0),
+      Res = Res0#katt_response{headers = Hdrs},
+      TransformFun(TransformId, {Res, ActualResponse}, Params, Callbacks)
+  end.

src/katt.hrl

@@ -54,6 +54,7 @@
 -define(DEFAULT_RECALL_FUN,         fun katt_callbacks:recall/4).
 -define(DEFAULT_REQUEST_FUN,        fun katt_callbacks:request/3).
 -define(DEFAULT_TEXT_DIFF_FUN,      fun katt_callbacks:text_diff/2).
+-define(DEFAULT_TRANSFORM_FUN,      fun katt_callbacks:transform/4).
 -define(DEFAULT_VALIDATE_FUN,       fun katt_callbacks:validate/4).
 
 -type params()              :: [{param_name(), param_value()}].

src/katt_callbacks.erl

@@ -33,6 +33,7 @@
         , validate_type/6
         , progress/2
         , text_diff/2
+        , transform/4
         ]).
 
 %%%_* Includes =================================================================
@@ -223,6 +224,18 @@ text_diff(A, B) ->
   [{text_diff, tdiff:diff(A, B)}].
 -endif.
 
+%% @doc Transform a request or a response
+%% @end
+-spec transform( list()
+               , request() | {response(), list()}
+               , params()
+               , callbacks()
+               ) -> request() | response().
+transform(_Id, #katt_request{} = Req, _Params, _Callbacks) ->
+  Req;
+transform(_Id, {#katt_response{} = Res, _Actual}, _Params, _Callbacks) ->
+  Res.
+
 %%%_* Internal =================================================================
 
 http_request( #katt_request{ method = Method