Added center_text() utility function for centering text in a terminal along with unit tests for it

This function isn't used yet, but I have plans to use it when improving the output of transcript testing

Author: tleonhardt

cmd2/utils.py

@@ -5,6 +5,7 @@
 import glob
 import os
 import re
+import shutil
 import subprocess
 import sys
 import threading
@@ -377,6 +378,21 @@ def get_exes_in_path(starts_with: str) -> List[str]:
     return list(exes_set)
 
 
+def center_text(msg: str, *, pad: str = ' ') -> str:
+    """Centers text horizontally for display within the current terminal, optionally padding both sides.
+
+    :param msg: message to display in the center
+    :param pad: (optional) if provided, the first character will be used to pad both sides of the message
+    :return: centered message, optionally padded on both sides with pad_char
+    """
+    term_width = shutil.get_terminal_size().columns
+    surrounded_msg = ' {} '.format(msg)
+    if not pad:
+        pad = ' '
+    fill_char = pad[:1]
+    return surrounded_msg.center(term_width, fill_char)
+
+
 class StdSim(object):
     """
     Class to simulate behavior of sys.stdout or sys.stderr.

tests/test_utils.py

@@ -276,3 +276,26 @@ def test_context_flag_bool(context_flag):
 def test_context_flag_exit_err(context_flag):
     with pytest.raises(ValueError):
         context_flag.__exit__()
+
+
+def test_center_text_pad_none():
+    msg = 'foo'
+    centered = cu.center_text(msg, pad=None)
+    expected_center = ' ' + msg + ' '
+    assert expected_center in centered
+    letters_in_centered = set(centered)
+    letters_in_msg = set(msg)
+    assert len(letters_in_centered) == len(letters_in_msg) + 1
+
+def test_center_text_pad_equals():
+    msg = 'foo'
+    pad = '='
+    centered = cu.center_text(msg, pad=pad)
+    expected_center = ' ' + msg + ' '
+    assert expected_center in centered
+    assert centered.startswith(pad)
+    assert centered.endswith(pad)
+    letters_in_centered = set(centered)
+    letters_in_msg = set(msg)
+    assert len(letters_in_centered) == len(letters_in_msg) + 2
+