From c46d80b8be510fd3a6897e16edcf2105aaaf6500 Mon Sep 17 00:00:00 2001
From: yash-nisar <yash.nisar@somaiya.edu>
Date: Sun, 6 Aug 2017 12:50:13 +0530
Subject: [PATCH] TravisLintBear: Check for internet connection

Add a check for internet connection in the `check_prerequisites`
method without which the bear will fail to run.

Fixes https://github.com/coala/coala-bears/issues/1978
---
 bears/yaml/TravisLintBear.py     | 25 +++++++++++++++++++++++++
 tests/yaml/TravisLintBearTest.py | 18 ++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/bears/yaml/TravisLintBear.py b/bears/yaml/TravisLintBear.py
index f6400403b3..be582a90c1 100644
--- a/bears/yaml/TravisLintBear.py
+++ b/bears/yaml/TravisLintBear.py
@@ -1,3 +1,5 @@
+import requests
+
 from coalib.bearlib.abstractions.Linter import linter
 
 from dependency_management.requirements.GemRequirement import GemRequirement
@@ -24,6 +26,29 @@ class TravisLintBear:
     LICENSE = 'AGPL-3.0'
     CAN_DETECT = {'Formatting', 'Syntax'}
     SEE_MORE = 'https://docs.travis-ci.com/user/travis-lint'
+    CHECK_CONNECTION_URL = 'https://travis-ci.org/'
+
+    @classmethod
+    def check_prerequisites(cls):  # pragma: no cover
+        url_status = cls.get_status_of_url(cls.CHECK_CONNECTION_URL)
+        base_check = super().check_prerequisites()
+        if base_check is not True:
+            return base_check
+        try:
+            if url_status is None:
+                return 'You are not connected to the internet.'
+            else:
+                url_status.raise_for_status()
+                return True
+        except requests.exceptions.HTTPError:
+            return 'Failed to establish a connection to the server.'
+
+    @staticmethod
+    def get_status_of_url(url):
+        try:
+            return requests.head(url, allow_redirects=False)
+        except requests.exceptions.RequestException:
+            return None
 
     @staticmethod
     def create_arguments(filename, file, config_file):
diff --git a/tests/yaml/TravisLintBearTest.py b/tests/yaml/TravisLintBearTest.py
index 914badbf6a..aef779d392 100644
--- a/tests/yaml/TravisLintBearTest.py
+++ b/tests/yaml/TravisLintBearTest.py
@@ -1,4 +1,6 @@
 import os
+import requests
+import requests_mock
 from queue import Queue
 
 from coalib.results.Result import Result
@@ -71,3 +73,19 @@ def test_empty_file(self):
                                 file=get_testfile_path(file_name),
                                 severity=RESULT_SEVERITY.NORMAL)],
             filename=get_testfile_path(file_name))
+
+    def test_check_prerequisites(self):
+        with requests_mock.Mocker() as m:
+            m.head(TravisLintBear.CHECK_CONNECTION_URL,
+                   status_code=200)
+            self.assertTrue(TravisLintBear.check_prerequisites())
+
+            m.head(TravisLintBear.CHECK_CONNECTION_URL,
+                   exc=requests.exceptions.RequestException)
+            self.assertEqual(TravisLintBear.check_prerequisites(),
+                             'You are not connected to the internet.')
+
+            m.head(TravisLintBear.CHECK_CONNECTION_URL,
+                   status_code=404)
+            self.assertEqual(TravisLintBear.check_prerequisites(),
+                             'Failed to establish a connection to the server.')