diff --git a/src/bot_detector.js b/src/bot_detector.js
index 4291a7e..463fed4 100644
--- a/src/bot_detector.js
+++ b/src/bot_detector.js
@@ -16,14 +16,16 @@ module.exports = (config) => {
     };
 
     const fetchList = (cb) => {
+        const file = fs.createWriteStream(config['robots']['list_file']);
         https.get(config['robots']['list_url'], (res) => {
-            const file = fs.createWriteStream(config['robots']['list_file']);
             res.pipe(file);
             file.on('finish', () => {
                 file.close(cb);
             });
         }).on('error', (err) => {
-            cb(err.message);
+            file.close(() => {
+                cb(err.message);
+            });
         });
     };
 
@@ -45,9 +47,11 @@ module.exports = (config) => {
         fetchList((err) => {
             cb(err ? _this.status.FETCH_ERROR : _this.status.FETCH_OK, err);
             readFile((err, data) => {
-                _this.count = data.length;
-                _this.regex = new RegExp('(' + data.filter(v => v['pattern']).map(v => v['pattern'])
-                    .join('|') + ')');
+                if (!err) {
+                    _this.count = data.length;
+                    _this.regex = new RegExp('(' + data.filter(v => v['pattern']).map(v => v['pattern'])
+                        .join('|') + ')');
+                }
                 cb(err ? _this.status.READ_ERROR : _this.status.READ_OK, err);
             });
         });
diff --git a/test/bot_detector.test.js b/test/bot_detector.test.js
new file mode 100644
index 0000000..da4fc69
--- /dev/null
+++ b/test/bot_detector.test.js
@@ -0,0 +1,71 @@
+const fs = require('fs');
+const utils = require('./test_utils');
+
+const dataDir = 'test_data';
+
+const config = {
+    robots: {
+        list_url: 'https://raw.githubusercontent.com/atmire/COUNTER-Robots/master/COUNTER_Robots_list.json',
+        list_file: `${dataDir}/robots_list.json`,
+    },
+};
+
+
+beforeAll(() => {
+    utils.deleteFolderSync(dataDir);
+    fs.mkdirSync(dataDir);
+});
+
+afterAll(() => {
+    if (fs.existsSync(dataDir)) {
+        utils.deleteFolderSync(dataDir);
+    }
+});
+
+const botDetector = require('../src/bot_detector')(config);
+
+test('load()', (done) => {
+    let count = 0;
+    botDetector.load((status, err) => {
+        expect(err).not.toBeDefined();
+        expect(status).toBe(count === 0 ? botDetector.status.FETCH_OK : botDetector.status.READ_OK);
+        if (count > 0) {
+            done();
+        }
+        count++;
+    });
+});
+
+describe('handle()', () => {
+    beforeAll((done) => {
+        botDetector.load((status) => {
+            if (status === botDetector.status.READ_OK) {
+                done();
+            }
+        });
+    });
+
+    test('not bot', (done) => {
+        const req = {
+            headers: {
+                'user-agent': 'my user agent',
+            },
+        };
+        botDetector.handle(req, null, () => {
+            expect(req.isRobot).toBeFalsy();
+            done();
+        });
+    });
+
+    test('bot', (done) => {
+        const req = {
+            headers: {
+                'user-agent': 'bot',
+            },
+        };
+        botDetector.handle(req, null, () => {
+            expect(req.isRobot).toBeTruthy();
+            done();
+        });
+    });
+});