Made sure format_table doesn't change its input

frmt.py

@@ -20,6 +20,7 @@
 import math
 import numpy as np
 import shutil
+from copy import deepcopy
 
 def fit_text(text, width=None, align='<', suffix="..."):
     """
@@ -180,6 +181,8 @@ def format_table(table,
     'truncate' is 0, column 0 will have a width of -16 which is not permitted.
     """
 
+    table = deepcopy(table)
+
     if not isinstance(align, list):
         align = [align]
 

test_frmt.py

@@ -142,8 +142,45 @@ def test_format_table_example2b():
         "Stuart    48:54\n"\
         "John    1:01:12\n"
 
+def test_format_table_example2c():
+
+    header =  ['Name'  , 'Time']
+    table  = [['John'  , 3672  ],
+              ['Martha', 2879  ],
+              ['Stuart', 2934  ],
+              ['Eduard', 2592  ]]
+
+    table.sort(key=lambda row: row[1])
+
+    header.insert(0, '')
+    for i, row in enumerate(table):
+        row.insert(0, i+1)
+
+    table.insert(0, header)
+
+    def index(num):
+        if isinstance(num, int):
+            return "{}.".format(num)
+        else:
+            return num
+
+    assert format_table(table, '<<>', format=[index,format_time]) == \
+        "    Name       Time\n"\
+        "1.  Eduard    43:12\n"\
+        "2.  Martha    47:59\n"\
+        "3.  Stuart    48:54\n"\
+        "4.  John    1:01:12\n"
+
 def test_format_table_numcols():
 
     table = [[1, 2, 3],[1, 2]]
     with pytest.raises(ValueError) as e_info:
         format_table(table)
+
+def test_format_table_inputonlyargument():
+
+    # Make sure format_table isn't changing its input arguments.
+    # TBD: This test could perhaps be generalized to something.
+    table = [[1,2],[3,4]]
+    format_table(table, format=format_time)
+    assert table[1][1]==4