added a simple test for the host_redirect middleware using mocha and should.js

test/host_redirect.test.js

@@ -0,0 +1,50 @@
+(function() {
+  var host_rewrite;
+
+  require('should');
+
+  host_rewrite = require('../middleware/host_redirect');
+
+  describe('host_redirect', function() {
+    var redirect_map, redirector;
+    redirect_map = {
+      'www.foo.com': 'http://foo.com/',
+      'img.foo.com': 'http://images.foo.com/'
+    };
+    redirector = host_rewrite(redirect_map);
+    describe('when request does not match any entry in map', function() {
+      return it('next() is called to pass on the request', function(done) {
+        var next, req, res;
+        req = {
+          header: function() {
+            return 'www.bar.com';
+          }
+        };
+        res = {};
+        next = function() {
+          return done();
+        };
+        return redirector(req, res, next);
+      });
+    });
+    return describe('when request matches an entry in map', function() {
+      return it('req.redirect() is called with the new URL', function(done) {
+        var next, req, res;
+        req = {
+          header: function() {
+            return 'img.foo.com';
+          }
+        };
+        res = {
+          redirect: function(url) {
+            url.should.equal(redirect_map[req.header()]);
+            return done();
+          }
+        };
+        next = function() {};
+        return redirector(req, res, next);
+      });
+    });
+  });
+
+}).call(this);