Add custom parse function to rewrite response before writing to tape

README.md

@@ -33,6 +33,29 @@ var handler = yakbak('http://api.flickr.com', {
 
 - `dirname` the path where recorded responses will be written (required).
 - `noRecord` if true, requests will return a 404 error if the tape doesn't exist
+- `parse` optional hook function to modify the response before writing to a tape
+
+	```javascript
+	// Example that rewrites url in content body
+	parse: function (req, res, body) {
+		var isGzipped = req._headers['accept-encoding'].indexOf('gzip') > -1;
+		var replaceRe = new RegExp('http://api.flickr.com', 'g');
+
+		// Body is an array of Buffers
+		var newBody = body.map(function (chunk) {
+			if (isGzipped) {
+				chunk = zlib.gunzipSync(chunk);
+			}
+			var buffer = new Buffer(chunk.toString('utf8).replace(replaceRe, 'http://localhost:3000'));
+			if (isGzipped) {
+				buffer = zlib.gzipSync(buffer);
+			}
+			return buffer;
+		});
+
+		return { req: req, res: res, body: newBody };
+	}
+	```
 
 ### with node's http module
 

index.js

@@ -18,6 +18,7 @@ var debug = require('debug')('yakbak:server');
  * @param {Object} opts
  * @param {String} opts.dirname The tapes directory
  * @param {Boolean} opts.noRecord if true, requests will return a 404 error if the tape doesn't exist
+ * @param {Function} opts.parse hook to rewrite the response before writing to a tape
  * @returns {Function}
  */
 
@@ -40,7 +41,7 @@ module.exports = function (host, opts) {
           throw new RecordingDisabledError('Recording Disabled');
         } else {
           return proxy(req, body, host).then(function (pres) {
-            return record(pres.req, pres, file);
+            return record(pres.req, pres, file, opts.parse);
           });
         }
 

lib/record.js

@@ -23,12 +23,20 @@ var render = ejs.compile(fs.readFileSync(path.resolve(__dirname, '../src/tape.ej
  * @param {http.ClientRequest} req
  * @param {http.IncomingMessage} res
  * @param {String} filename
+ * @param {Function} parse
  * @returns {Promise.<String>}
  */
 
-module.exports = function (req, res, filename) {
+module.exports = function (req, res, filename, parse) {
   return buffer(res).then(function (body) {
-    return render({ req: req, res: res, body: body });
+    var data;
+
+    if (parse) {
+      data = parse(req, res, body);
+    } else {
+      data = { req: req, res: res, body: body };
+    }
+    return render(data);
   }).then(function (data) {
     return write(filename, data);
   }).then(function () {

test/fixtures/custom-parse.js

@@ -0,0 +1,25 @@
+var path = require("path");
+
+/**
+ * GET /
+ *
+ * host: {addr}:{port}
+ * user-agent: My User Agent/1.0
+ * connection: close
+ */
+
+module.exports = function (req, res) {
+  res.statusCode = 201;
+
+  res.setHeader("content-type", "text/html");
+  res.setHeader("date", "Sat, 26 Oct 1985 08:20:00 GMT");
+  res.setHeader("connection", "close");
+  res.setHeader("content-length", "2");
+
+  res.setHeader("x-yakbak-tape", path.basename(__filename, ".js"));
+
+  res.write(new Buffer("cGFyc2VkOjpPSw==", "base64"));
+  res.end();
+
+  return __filename;
+};

test/record.js

@@ -9,6 +9,7 @@ var createTmpdir = require('./helpers/tmpdir');
 var assert = require('assert');
 var http = require('http');
 var fs = require('fs');
+var path = require('path');
 
 var fixture = require('./fixtures');
 
@@ -68,4 +69,29 @@ describe('record', function () {
     req.end();
   });
 
+  it('uses the parse function if passed in', function (done) {
+    var customParseFixture = fs.readFileSync(path.join(__dirname, 'fixtures/custom-parse.js'), 'utf8');
+    var expected = customParseFixture.replace('{addr}', server.addr).replace('{port}', server.port);
+    var parse = function (preq, pres, pbody) {
+      var newBody = pbody.map(function (chunk) {
+        var str = 'parsed::' + chunk.toString('utf8');
+
+        return new Buffer(str, 'utf8');
+      });
+
+      return { req: preq, res: pres, body: newBody };
+    };
+
+    req.on('response', function (res) {
+      subject(req, res, tmpdir.join('foo.js'), parse).then(function (filename) {
+        assert.equal(fs.readFileSync(filename, 'utf8'), expected);
+        done();
+      }).catch(function (err) {
+        done(err);
+      });
+    });
+
+    req.end();
+  });
+
 });