fix_csv: bonus 1

fix_csv/fix_csv.py

@@ -1,27 +1,28 @@
 import logging
 from pathlib import Path
+import csv
 
 
 logging.basicConfig(level=logging.INFO)
 
 
-def escape(string):
+def normalise(input, output, in_delimiter="|", in_quote='"'):
-    """Return an escaped version of `string`."""
-    string = string.replace('"', '""')
-    if "," in string:
-        string = '"' + string + '"'
-    return string
-
-
-def normalise(input, output):
     """Normalise `input` CSV file into `output` file."""
     Path(output).touch(exist_ok=True)
-    with Path(input).open("r") as in_file, Path(output).open("w") as out_file:
+    with Path(input).open("r", newline="") as in_file, Path(output).open(
-        for in_line in in_file.readlines():
+        "w"
-            out_elements = [
+    ) as out_file:
-                escape(in_element) for in_element in in_line.strip().split("|")
+        reader = csv.reader(in_file, delimiter=in_delimiter, quotechar=in_quote)
-            ]
+        writer = csv.writer(
-            out_file.write(f"{','.join(out_elements)}\n")
+            out_file,
+            delimiter=",",
+            quotechar=in_quote,
+            quoting=csv.QUOTE_MINIMAL,
+            lineterminator="\n",
+        )
+        for row in reader:
+            row = [element.replace('"', '"""') for element in row]
+            writer.writerow(row)
 
 
 if __name__ == "__main__":
@@ -32,6 +33,14 @@ if __name__ == "__main__":
     parser.add_argument("input")
     parser.add_argument("output")
 
+    parser.add_argument("--in-delimiter", dest="in_delimiter", default="|")
+    parser.add_argument("--in-quote", dest="in_quote", default='"')
+
     args = parser.parse_args()
 
-    normalise(args.input, args.output)
+    normalise(
+        input=args.input,
+        output=args.output,
+        in_delimiter=args.in_delimiter,
+        in_quote=args.in_quote,
+    )

fix_csv/test_fix_csv.py

@@ -17,29 +17,34 @@ class FixCSVTests(unittest.TestCase):
     maxDiff = None
 
     def test_pipe_file_to_csv_file(self):
-        old_contents = dedent("""
+        old_contents = dedent(
+            """
             2012|Lexus|LFA
             2009|GMC|Yukon XL 1500
             1965|Ford|Mustang
             2005|Hyundai|Sonata
             1995|Mercedes-Benz|C-Class
-        """).lstrip()
+        """
-        expected = dedent("""
+        ).lstrip()
+        expected = dedent(
+            """
             2012,Lexus,LFA
             2009,GMC,Yukon XL 1500
             1965,Ford,Mustang
             2005,Hyundai,Sonata
             1995,Mercedes-Benz,C-Class
-        """).lstrip()
+        """
+        ).lstrip()
         with make_file(old_contents) as old, make_file("") as new:
-            output = run_program(f'fix_csv.py {old} {new}')
+            output = run_program(f"fix_csv.py {old} {new}")
             with open(new) as new_file:
                 new_contents = new_file.read()
         self.assertEqual(expected, new_contents)
         self.assertEqual("", output)
 
     def test_delimiter_in_output(self):
-        old_contents = dedent("""
+        old_contents = dedent(
+            """
             02|Waylon Jennings|Honky Tonk Heroes (Like Me)
             04|Kris Kristofferson|To Beat The Devil
             11|Johnny Cash|Folsom Prison Blues
@@ -47,8 +52,10 @@ class FixCSVTests(unittest.TestCase):
             21|Hank Williams III|Mississippi Mud
             22|David Allan Coe|Willie, Waylon, And Me
             24|Bob Dylan|House Of The Risin' Sun
-        """).lstrip()
+        """
-        expected = dedent("""
+        ).lstrip()
+        expected = dedent(
+            """
             02,Waylon Jennings,Honky Tonk Heroes (Like Me)
             04,Kris Kristofferson,To Beat The Devil
             11,Johnny Cash,Folsom Prison Blues
@@ -56,21 +63,24 @@ class FixCSVTests(unittest.TestCase):
             21,Hank Williams III,Mississippi Mud
             22,David Allan Coe,"Willie, Waylon, And Me"
             24,Bob Dylan,House Of The Risin' Sun
-        """).lstrip()
+        """
+        ).lstrip()
         with make_file(old_contents) as old, make_file("") as new:
-            output = run_program(f'fix_csv.py {old} {new}')
+            output = run_program(f"fix_csv.py {old} {new}")
             with open(new) as new_file:
                 new_contents = new_file.read()
         self.assertEqual(expected, new_contents)
         self.assertEqual("", output)
 
     def test_original_file_is_unchanged(self):
-        old_contents = dedent("""
+        old_contents = dedent(
+            """
             2012|Lexus|LFA
             2009|GMC|Yukon XL 1500
-        """).lstrip()
+        """
+        ).lstrip()
         with make_file(old_contents) as old, make_file("") as new:
-            run_program(f'fix_csv.py {old} {new}')
+            run_program(f"fix_csv.py {old} {new}")
             with open(old) as old_file:
                 contents = old_file.read()
         self.assertEqual(old_contents, contents)
@@ -78,54 +88,63 @@ class FixCSVTests(unittest.TestCase):
     def test_call_with_too_many_files(self):
         with make_file("") as old, make_file("") as new:
             with self.assertRaises(BaseException):
-                run_program(f'fix_csv.py {old} {new} {old}')
+                run_program(f"fix_csv.py {old} {new} {old}")
 
     # To test the Bonus part of this exercise, comment out the following line
-    @unittest.expectedFailure
+    # @unittest.expectedFailure
     def test_in_delimiter_and_in_quote(self):
-        old_contents = dedent("""
+        old_contents = dedent(
+            """
             2012 Lexus "LFA"
             2009 GMC 'Yukon XL 1500'
             1995 "Mercedes-Benz" C-Class
-        """).lstrip()
+        """
-        expected1 = dedent("""
+        ).lstrip()
+        expected1 = dedent(
+            """
             2012,Lexus,LFA
             2009,GMC,'Yukon,XL,1500'
             1995,Mercedes-Benz,C-Class
-        """).lstrip()
+        """
-        expected2 = dedent('''
+        ).lstrip()
+        expected2 = dedent(
+            '''
             2012,Lexus,"""LFA"""
             2009,GMC,Yukon XL 1500
             1995,"""Mercedes-Benz""",C-Class
-        ''').lstrip()
+        '''
+        ).lstrip()
         with make_file(old_contents) as old, make_file("") as new:
             run_program(f'fix_csv.py {old} {new} --in-delimiter=" "')
             with open(new) as new_file:
                 self.assertEqual(expected1, new_file.read())
-            run_program(
+            run_program(f"""fix_csv.py --in-delimiter=" " --in-quote="'" {old} {new}""")
-                f'''fix_csv.py --in-delimiter=" " --in-quote="'" {old} {new}'''
-            )
             with open(new) as new_file:
                 self.assertEqual(expected2, new_file.read())
 
     # To test the Bonus part of this exercise, comment out the following line
-    @unittest.expectedFailure
+    # @unittest.expectedFailure
     def test_autodetect_input_format(self):
-        contents1 = dedent("""
+        contents1 = dedent(
+            """
             '2012' 'Lexus' 'LFA'
             '2009' 'GMC' 'Yukon XL 1500'
             '1995' 'Mercedes-Benz' 'C-Class'
-        """).lstrip()
+        """
-        expected1 = dedent("""
+        ).lstrip()
+        expected1 = dedent(
+            """
             2012,Lexus,LFA
             2009,GMC,Yukon XL 1500
             1995,Mercedes-Benz,C-Class
-        """).lstrip()
+        """
+        ).lstrip()
         with make_file(contents1) as old, make_file("") as new:
-            run_program(f'fix_csv.py {old} {new}')
+            run_program(f"fix_csv.py {old} {new}")
             with open(new) as new_file:
                 self.assertEqual(expected1, new_file.read())
-        contents2 = dedent("""
+        contents2 = dedent(
+            """
             "02"\t"Waylon Jennings"\t"Honky Tonk Heroes (Like Me)"\t"3:29"
             "04"\t"Kris Kristofferson"\t"To Beat The Devil"\t"4:05"
             "11"\t"Johnny Cash"\t"Folsom Prison Blues"\t"2:51"
@@ -133,8 +152,10 @@ class FixCSVTests(unittest.TestCase):
             "21"\t"Hank Williams III"\t"Mississippi Mud"\t"3:32"
             "22"\t"David Allan Coe"\t"Willie, Waylon, And Me"\t"3:24"
             "24"\t"Bob Dylan"\t"House Of The Risin' Sun"\t"5:20"
-        """).lstrip()
+        """
-        expected2 = dedent("""
+        ).lstrip()
+        expected2 = dedent(
+            """
             02,Waylon Jennings,Honky Tonk Heroes (Like Me),3:29
             04,Kris Kristofferson,To Beat The Devil,4:05
             11,Johnny Cash,Folsom Prison Blues,2:51
@@ -142,9 +163,10 @@ class FixCSVTests(unittest.TestCase):
             21,Hank Williams III,Mississippi Mud,3:32
             22,David Allan Coe,"Willie, Waylon, And Me",3:24
             24,Bob Dylan,House Of The Risin' Sun,5:20
-        """).lstrip()
+        """
+        ).lstrip()
         with make_file(contents2) as old, make_file("") as new:
-            run_program(f'fix_csv.py {old} {new}')
+            run_program(f"fix_csv.py {old} {new}")
             with open(new) as new_file:
                 self.assertEqual(expected2, new_file.read())
 
@@ -159,25 +181,25 @@ def run_program(arguments="", raises=DummyException):
 
     If raises is specified, ensure the given exception is raised.
     """
-    arguments = arguments.replace('\\', '\\\\')
+    arguments = arguments.replace("\\", "\\\\")
     path, *args = shlex.split(arguments)
     old_args = sys.argv
     warnings.simplefilter("ignore", ResourceWarning)
     try:
         sys.argv = [path] + args
         try:
-            if '__main__' in sys.modules:
+            if "__main__" in sys.modules:
-                del sys.modules['__main__']
+                del sys.modules["__main__"]
             with redirect_stdout(StringIO()) as output:
                 with redirect_stderr(output):
-                    SourceFileLoader('__main__', path).load_module()
+                    SourceFileLoader("__main__", path).load_module()
         except raises:
             return output.getvalue()
         except SystemExit as e:
             if e.args != (0,):
                 raise SystemExit(output.getvalue()) from e
         finally:
-            sys.modules.pop('__main__', None)
+            sys.modules.pop("__main__", None)
         if raises is not DummyException:
             raise AssertionError("{} not raised".format(raises))
         return output.getvalue()
@@ -188,7 +210,7 @@ def run_program(arguments="", raises=DummyException):
 @contextmanager
 def make_file(contents=None):
     """Context manager providing name of a file containing given contents."""
-    with NamedTemporaryFile(mode='wt', encoding='utf-8', delete=False) as f:
+    with NamedTemporaryFile(mode="wt", encoding="utf-8", delete=False) as f:
         if contents:
             f.write(contents)
     try: