Add an SSHConfig dict to provide type conversion helpers

2 files changed, 71 insertions, 0 deletions

diff --git a/paramiko/config.py b/paramiko/config.py
index 038d84ea..22e2e2b3 100644
--- a/paramiko/config.py
+++ b/paramiko/config.py
@@ -21,6 +21,7 @@
 Configuration file (aka ``ssh_config``) support.
 """
 
+import collections
 import fnmatch
 import os
 import re
@@ -295,3 +296,28 @@ class LazyFqdn(object):
             # Cache
             self.fqdn = fqdn
         return self.fqdn
+
+
+class SSHConfigDict(collections.UserDict):
+    """A dictionary wrapper for ssh host configurations.
+
+    This class introduces some usage niceties for consumers of SSHConfig,
+    specifically around the issue of variable type conversions. This offers
+    as_bool(key) and as_int(key) for the current raw string values in
+    SSHConfig"""
+
+    def __init__(self, initialdata=None):
+        super(SSHConfigDict, self).__init__(initialdata)
+
+    def as_bool(self, key):
+        """Express the key as a boolean value. Variations on 'yes' or boolean values
+        are accepted."""
+        val = self[key]
+        if isinstance(val, bool):
+            return val
+        return val.lower() == 'yes'
+
+    def as_int(self, key):
+        """Express the key as a true integer, if possible. Raises an Error otherwise
+        (following conventional int conversion rules)"""
+        return int(self[key])
diff --git a/tests/test_config.py b/tests/test_config.py
new file mode 100644
index 00000000..9edab3d9
--- /dev/null
+++ b/tests/test_config.py
@@ -0,0 +1,45 @@
+# This file is part of Paramiko and subject to the license in /LICENSE in this
+# repository
+
+import pytest
+from paramiko import config
+
+
+def test_SSHConfigDict_construct_empty():
+    assert not config.SSHConfigDict()
+
+
+def test_SSHConfigDict_construct_from_list():
+    assert config.SSHConfigDict([(1, 2)])[1] == 2
+
+
+def test_SSHConfigDict_construct_from_dict():
+    assert config.SSHConfigDict({1: 2})[1] == 2
+
+
+@pytest.mark.parametrize("true_ish", ("yes", "YES", "Yes", True))
+def test_SSHConfigDict_as_bool_true_ish(true_ish):
+    assert config.SSHConfigDict({"key": true_ish}).as_bool("key") is True
+
+
+@pytest.mark.parametrize("false_ish", ("no", "NO", "No", False))
+def test_SSHConfigDict_as_bool(false_ish):
+    assert config.SSHConfigDict({"key": false_ish}).as_bool("key") is False
+
+
+@pytest.mark.parametrize("int_val", ("42", 42))
+def test_SSHConfigDict_as_int(int_val):
+    assert config.SSHConfigDict({"key": int_val}).as_int("key") == 42
+
+
+@pytest.mark.parametrize("non_int", ("not an int", None, object()))
+def test_SSHConfigDict_as_int_failures(non_int):
+    conf = config.SSHConfigDict({"key": non_int})
+
+    try:
+        int(non_int)
+    except Exception as e:
+        exception_type = type(e)
+
+    with pytest.raises(exception_type):
+        conf.as_int("key")