Add test for console-log and docs for bug 1746534

We had no unit test coverage for the console-log command
so this adds a simple test. It unfortunately does not
recreate the original UnicodeEncodeError bug though, but
it gives us some test coverage anyway.

This change also adds docs on how to resolve bug 1746534
by configuring the environment for UTF-8 as noted in
the revert change Iaeec1e74262a35f3de3c81f7013835a6aa6f9029.

The documentation added here is shamelessly copied from
Click [1] which was found via the PEP 538 docs [2].

[1] https://click.palletsprojects.com/en/5.x/python3/#python-3-surrogate-handling
[2] https://www.python.org/dev/peps/pep-0538/

Change-Id: Ic7059260dfc031ea1b08d2b8a7cec684bbe7dfa5
Related-Bug: #1823287
Related-Bug: #1746534

doc/source/cli/nova.rst

@@ -1177,6 +1177,33 @@ nova console-log
 
 Get console log output of a server.
 
+**Locale encoding issues**
+
+If you encounter an error such as:
+
+.. code-block:: console
+
+  UnicodeEncodeError: 'ascii' codec can't encode characters in position
+
+The solution to these problems is different depending on which locale your
+computer is running in.
+
+For instance, if you have a German Linux machine, you can fix the problem by
+exporting the locale to de_DE.utf-8:
+
+.. code-block:: console
+
+  export LC_ALL=de_DE.utf-8
+  export LANG=de_DE.utf-8
+
+If you are on a US machine, en_US.utf-8 is the encoding of choice. On some
+newer Linux systems, you could also try C.UTF-8 as the locale:
+
+.. code-block:: console
+
+  export LC_ALL=C.UTF-8
+  export LANG=C.UTF-8
+
 **Positional arguments:**
 
 ``<server>``

novaclient/tests/unit/v2/test_shell.py

@@ -3553,6 +3553,12 @@ class ShellTest(utils.TestCase):
         self.run_command('availability-zone-list')
         self.assert_called('GET', '/os-availability-zone/detail')
 
+    def test_console_log(self):
+        out = self.run_command('console-log --length 20 1234')[0]
+        self.assert_called('POST', '/servers/1234/action',
+                           body={'os-getConsoleOutput': {'length': '20'}})
+        self.assertIn('foo', out)
+
     def test_server_security_group_add(self):
         self.run_command('add-secgroup sample-server testgroup')
         self.assert_called('POST', '/servers/1234/action',