Fixed #23658 -- Provided the password to PostgreSQL dbshell command

The password from settings.py is written in a temporary .pgpass file
file whose name is given to psql using the PGPASSFILE environment
variable.

tests/dbshell/test_postgresql_psycopg2.py

@@ -0,0 +1,117 @@
+# -*- coding: utf8 -*-
+from __future__ import unicode_literals
+
+import locale
+import os
+
+from django.db.backends.postgresql_psycopg2.client import DatabaseClient
+from django.test import SimpleTestCase, mock
+from django.utils import six
+from django.utils.encoding import force_bytes, force_str
+
+
+class PostgreSqlDbshellCommandTestCase(SimpleTestCase):
+
+    def _run_it(self, dbinfo):
+        """
+        That function invokes the runshell command, while mocking
+        subprocess.call. It returns a 2-tuple with:
+        - The command line list
+        - The binary content of file pointed by environment PGPASSFILE, or
+          None.
+        """
+        def _mock_subprocess_call(*args):
+            self.subprocess_args = list(*args)
+            if 'PGPASSFILE' in os.environ:
+                self.pgpass = open(os.environ['PGPASSFILE'], 'rb').read()
+            else:
+                self.pgpass = None
+            return 0
+        self.subprocess_args = None
+        self.pgpass = None
+        with mock.patch('subprocess.call', new=_mock_subprocess_call):
+            DatabaseClient.runshell_db(dbinfo)
+        return self.subprocess_args, self.pgpass
+
+    def test_basic(self):
+        self.assertEqual(
+            self._run_it({
+                'NAME': 'dbname',
+                'USER': 'someuser',
+                'PASSWORD': 'somepassword',
+                'HOST': 'somehost',
+                'PORT': 444,
+            }), (
+                ['psql', '-U', 'someuser', '-h', 'somehost', '-p', '444', 'dbname'],
+                b'somehost:444:dbname:someuser:somepassword\n',
+            )
+        )
+
+    def test_nopass(self):
+        self.assertEqual(
+            self._run_it({
+                'NAME': 'dbname',
+                'USER': 'someuser',
+                'HOST': 'somehost',
+                'PORT': 444,
+            }), (
+                ['psql', '-U', 'someuser', '-h', 'somehost', '-p', '444', 'dbname'],
+                None,
+            )
+        )
+
+    def test_column(self):
+        self.assertEqual(
+            self._run_it({
+                'NAME': 'dbname',
+                'USER': 'some:user',
+                'PASSWORD': 'some:password',
+                'HOST': '::1',
+                'PORT': 444,
+            }), (
+                ['psql', '-U', 'some:user', '-h', '::1', '-p', '444', 'dbname'],
+                b'\\:\\:1:444:dbname:some\\:user:some\\:password\n',
+            )
+        )
+
+    def test_escape_characters(self):
+        self.assertEqual(
+            self._run_it({
+                'NAME': 'dbname',
+                'USER': 'some\\user',
+                'PASSWORD': 'some\\password',
+                'HOST': 'somehost',
+                'PORT': 444,
+            }), (
+                ['psql', '-U', 'some\\user', '-h', 'somehost', '-p', '444', 'dbname'],
+                b'somehost:444:dbname:some\\\\user:some\\\\password\n',
+            )
+        )
+
+    def test_accent(self):
+        # The pgpass temporary file needs to be encoded using the system locale.
+        encoding = locale.getpreferredencoding()
+        username = 'rôle'
+        password = 'sésame'
+        try:
+            username_str = force_str(username, encoding)
+            password_str = force_str(password, encoding)
+            pgpass_bytes = force_bytes(
+                'somehost:444:dbname:%s:%s\n' % (username, password),
+                encoding=encoding,
+            )
+        except UnicodeEncodeError:
+            if six.PY2:
+                self.skipTest("Your locale can't run this test.")
+        self.assertEqual(
+            self._run_it({
+                'NAME': 'dbname',
+                'USER': username_str,
+                'PASSWORD': password_str,
+                'HOST': 'somehost',
+                'PORT': 444,
+            }), (
+                ['psql', '-U', username_str, '-h', 'somehost', '-p', '444', 'dbname'],
+                pgpass_bytes,
+            )
+        )