[SHELL] Extends entry support when SHELL env. var. is not propagated

archey/entries/shell.py

@@ -2,13 +2,26 @@
 
 import os
 
+from subprocess import CalledProcessError, check_output
+
 from archey.configuration import Configuration
 
 
 class Shell:
-    """Simple shell detection based on the `SHELL` environment variable"""
+    """
+    Simple shell path detection based either on the `SHELL` environment variable or
+    the local administrative database.
+    """
     def __init__(self):
-        self.value = os.getenv(
-            'SHELL',
-            Configuration().get('default_strings')['not_detected']
-        )
+        shell = os.getenv('SHELL')
+        if not shell:
+            try:
+                shell = check_output(
+                    ['getent', 'passwd', str(os.getuid())],
+                    universal_newlines=True
+                ).rstrip().split(':')[-1]
+            except CalledProcessError:
+                # Where does this user come from ?
+                shell = Configuration().get('default_strings')['not_detected']
+
+        self.value = shell

archey/test/test_archey_shell.py

@@ -1,5 +1,7 @@
 """Test module for Archey's shell detection module"""
 
+from subprocess import CalledProcessError
+
 import unittest
 from unittest.mock import patch
 
@@ -14,10 +16,41 @@ class TestShellEntry(unittest.TestCase):
         'archey.entries.shell.os.getenv',
         return_value='SHELL'
     )
-    def test(self, _):
+    def test_getenv(self, _):
         """Simple mock, simple test"""
         self.assertEqual(Shell().value, 'SHELL')
 
+    @patch(
+        'archey.entries.shell.os.getenv',
+        return_value=None
+    )
+    @patch(
+        'archey.entries.shell.os.getuid',  # We DO NOT HAVE TO mock this call.
+        return_value=1000
+    )
+    @patch(
+        'archey.entries.shell.check_output',
+        return_value="USERNAME:x:1000:1000:User Name,,,:/home/user:/bin/bash\n"
+    )
+    def test_getent_call(self, _, __, ___):
+        """Mock `getent` returned value and check the correct assignment"""
+        self.assertEqual(Shell().value, '/bin/bash')
+
+    @patch(
+        'archey.entries.shell.os.getenv',
+        return_value=None
+    )
+    @patch(
+        'archey.entries.shell.check_output',
+        side_effect=CalledProcessError(2, 'getent')
+    )
+    @patch(
+        'archey.entries.shell.Configuration.get',
+        return_value={'not_detected': 'Not detected'}
+    )
+    def test_config_fall_back(self, _, __, ___):
+        """`id` fails, but Archey must not !"""
+        self.assertEqual(Shell().value, 'Not detected')
 
 if __name__ == '__main__':
     unittest.main()