Detect OpenSSH private keys

tests/detect_private_key_test.py

@@ -0,0 +1,23 @@
+import os.path
+
+import pytest
+
+from pre_commit_hooks.detect_private_key import detect_private_key
+
+# Input, expected return value
+TESTS = (
+    (b'-----BEGIN RSA PRIVATE KEY-----', 1),
+    (b'-----BEGIN DSA PRIVATE KEY-----', 1),
+    (b'ssh-rsa DATA', 0),
+    (b'ssh-dsa DATA', 0),
+)
+
+
+@pytest.mark.parametrize(('input_s', 'expected_retval'), TESTS)
+def test_detect_private_key(input_s, expected_retval, tmpdir):
+    path = os.path.join(tmpdir.strpath, 'file.txt')
+
+    with open(path, 'wb') as file_obj:
+        file_obj.write(input_s)
+
+    assert detect_private_key([path]) == expected_retval