Added simple tests and CI

.github/workflows/ci.yml

@@ -0,0 +1,27 @@
+name: CI
+
+on:
+  push:
+    branches: [master]
+  pull_request: {}
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: [3.5, 3.6, 3.7, 3.8, 3.9]
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v2
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Install test dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install pytest
+    - name: Test with pytest
+      run: |
+        pytest

MANIFEST.in

@@ -1 +1,4 @@
 include MANIFEST.in README.rst LICENSE certifi/cacert.pem
+
+exclude .github/
+recursive-exclude .github

certifi/tests/test_certify.py

@@ -0,0 +1,15 @@
+# -*- coding: utf-8 -*-
+
+import os
+import unittest
+
+import certifi
+
+
+class TestCertifi(unittest.TestCase):
+    def test_cabundle_exists(self):
+        assert os.path.exists(certifi.where())
+
+    def test_read_contents(self):
+        content = certifi.contents()
+        assert "-----BEGIN CERTIFICATE-----" in content