test: include edge case tests for res.type() (#7037)

Author: IshitaSingh0822

test/res.type.js

@@ -42,5 +42,74 @@ describe('res', function(){
       .get('/')
       .expect('Content-Type', 'application/vnd.amazon.ebook', done);
     })
+
+    describe('edge cases', function(){
+      it('should handle empty string gracefully', function(done){
+        var app = express();
+
+        app.use(function(req, res){
+          res.type('').end('test');
+        });
+
+        request(app)
+        .get('/')
+        .expect('Content-Type', 'application/octet-stream')
+        .end(done);
+      })
+
+      it('should handle file extension with dots', function(done){
+        var app = express();
+
+        app.use(function(req, res){
+          res.type('.json').end('{"test": true}');
+        });
+
+        request(app)
+        .get('/')
+        .expect('Content-Type', 'application/json; charset=utf-8')
+        .end(done);
+      })
+
+      it('should handle multiple file extensions', function(done){
+        var app = express();
+
+        app.use(function(req, res){
+          res.type('file.tar.gz').end('compressed');
+        });
+
+        request(app)
+        .get('/')
+        .expect('Content-Type', 'application/gzip')
+        .end(done);
+      })
+
+      it('should handle uppercase extensions', function(done){
+        var app = express();
+
+        app.use(function(req, res){
+          res.type('FILE.JSON').end('{"test": true}');
+        });
+
+        request(app)
+        .get('/')
+        .expect('Content-Type', 'application/json; charset=utf-8')
+        .end(done);
+      })
+
+      it('should handle extension with special characters', function(done){
+        var app = express();
+
+        app.use(function(req, res){
+          res.type('file@test.json').end('{"test": true}');
+        });
+
+        request(app)
+        .get('/')
+        .expect('Content-Type', 'application/json; charset=utf-8')
+        .end(done);
+      })
+    })
   })
 })
+
+