Feature/check barcodes (#255)

* add a method to check barcode code format

ensure that the code to print is compatible with the ESC/POS formats and
also automatically check this format before printing (barcode() method).

* rewrite test using pytest's parametrize functionality

* add test for the 'check' argument

* update authors list

AUTHORS

@@ -12,6 +12,7 @@ Hark
 Joel Lehtonen
 Kristi
 ldos
+Lucy Linder
 Manuel F Martinez
 Michael Billington
 Michael Elsdörfer

src/escpos/constants.py

@@ -225,6 +225,24 @@ BARCODE_TYPE_B = {
     'GS1 DATABAR EXPANDED':        _SET_BARCODE_TYPE(78),
 }
 
+BARCODE_FORMATS = {
+    'UPC-A':                       ([(11, 12)], "^[0-9]{11,12}$"),
+    'UPC-E':                       ([(7, 8), (11, 12)], "^([0-9]{7,8}|[0-9]{11,12})$"),
+    'EAN13':                       ([(12, 13)], "^[0-9]{12,13}$"),
+    'EAN8':                        ([(7, 8)], "^[0-9]{7,8}$"),
+    'CODE39':                      ([(1, 255)], "^([0-9A-Z \$\%\+\-\.\/]+|\*[0-9A-Z \$\%\+\-\.\/]+\*)$"),
+    'ITF':                         ([(2, 255)], "^([0-9]{2})+$"),
+    'NW7':                         ([(1, 255)], "^[A-Da-d][0-9\$\+\-\.\/\:]+[A-Da-d]$"),
+    'CODABAR':                     ([(1, 255)], "^[A-Da-d][0-9\$\+\-\.\/\:]+[A-Da-d]$"),  # Same as NW7
+    'CODE93':                      ([(1, 255)], "^[\\x00-\\x7F]+$"),
+    'CODE128':                     ([(2, 255)], "^\{[A-C][\\x00-\\x7F]+$"),
+    'GS1-128':                     ([(2, 255)], "^\{[A-C][\\x00-\\x7F]+$"), # same as CODE128
+    'GS1 DATABAR OMNIDIRECTIONAL': ([(13,13)], "^[0-9]{13}$"),
+    'GS1 DATABAR TRUNCATED':       ([(13,13)], "^[0-9]{13}$"), # same as GS1 omnidirectional
+    'GS1 DATABAR LIMITED':         ([(13,13)], "^[01][0-9]{12}$"),
+    'GS1 DATABAR EXPANDED':        ([(2,255)], "^\([0-9][A-Za-z0-9 \!\"\%\&\'\(\)\*\+\,\-\.\/\:\;\<\=\>\?\_\{]+$"),
+}
+
 BARCODE_TYPES = {
     'A': BARCODE_TYPE_A,
     'B': BARCODE_TYPE_B,

src/escpos/escpos.py

@@ -19,13 +19,14 @@ import qrcode
 import textwrap
 import six
 import time
+from re import match as re_match
 
 import barcode
 from barcode.writer import ImageWriter
 
 from .constants import ESC, GS, NUL, QR_ECLEVEL_L, QR_ECLEVEL_M, QR_ECLEVEL_H, QR_ECLEVEL_Q
 from .constants import QR_MODEL_1, QR_MODEL_2, QR_MICRO, BARCODE_TYPES, BARCODE_HEIGHT, BARCODE_WIDTH
-from .constants import BARCODE_FONT_A, BARCODE_FONT_B
+from .constants import BARCODE_FONT_A, BARCODE_FONT_B, BARCODE_FORMATS
 from .constants import BARCODE_TXT_OFF, BARCODE_TXT_BTH, BARCODE_TXT_ABV, BARCODE_TXT_BLW
 from .constants import TXT_SIZE, TXT_NORMAL
 from .constants import SET_FONT
@@ -287,17 +288,42 @@ class Escpos(object):
         else:
             self.magic.force_encoding(code)
 
+    @staticmethod
+    def check_barcode(bc, code):
+        """
+        This method checks if the barcode is in the proper format.
+        The validation concerns the barcode length and the set of characters, but won't compute/validate any checksum.
+        The full set of requirement for each barcode type is available in the ESC/POS documentation.
+
+        As an example, using EAN13, the barcode `12345678901` will be correct, because it can be rendered by the
+        printer. But it does not suit the EAN13 standard, because the checksum digit is missing. Adding a wrong
+        checksum in the end will also be considered correct, but adding a letter won't (EAN13 is numeric only).
+
+        .. todo:: Add a method to compute the checksum for the different standards
+
+        .. todo:: For fixed-length standards with mandatory checksum (EAN, UPC),
+            compute and add the checksum automatically if missing.
+
+        :param bc: barcode format, see :py:func`~escpos.Escpos.barcode`
+        :param code: alphanumeric data to be printed as bar code, see :py:func`~escpos.Escpos.barcode`
+        :return: bool
+        """
+        if bc not in BARCODE_FORMATS:
+            return False
+
+        bounds, regex = BARCODE_FORMATS[bc]
+        return any(bound[0] <= len(code) <= bound[1] for bound in bounds) and re_match(regex, code)
+
     def barcode(self, code, bc, height=64, width=3, pos="BELOW", font="A",
-                align_ct=True, function_type=None):
+                align_ct=True, function_type=None, check=True):
         """ Print Barcode
 
         This method allows to print barcodes. The rendering of the barcode is done by the printer and therefore has to
-        be supported by the unit. Currently you have to check manually whether your barcode text is correct. Uncorrect
+        be supported by the unit. By default, this method will check whether your barcode text is correct, that is
-        barcodes may lead to unexpected printer behaviour. There are two forms of the barcode function. Type A is
+        the characters and lengths are supported by ESCPOS. Call the method with `check=False` to disable the check, but
-        default but has fewer barcodes, while type B has some more to choose from.
+        note that uncorrect barcodes may lead to unexpected printer behaviour.
-
+        There are two forms of the barcode function. Type A is default but has fewer barcodes,
-        .. todo:: Add a method to check barcode codes. Alternatively or as an addition write explanations about each
+        while type B has some more to choose from.
-                  barcode-type. Research whether the check digits can be computed autmatically.
 
         Use the parameters `height` and `width` for adjusting of the barcode size. Please take notice that the barcode
         will not be printed if it is outside of the printable area. (Which should be impossible with this method, so
@@ -365,6 +391,10 @@ class Escpos(object):
             function based on the current profile.
             *default*: A
 
+        :param check: If this parameter is True, the barcode format will be checked to ensure it meets the bc
+            requirements as defigned in the esc/pos documentation. See py:func:`~escpos.Escpos.check_barcode`
+            for more information. *default*: True.
+
         :raises: :py:exc:`~escpos.exceptions.BarcodeSizeError`,
                  :py:exc:`~escpos.exceptions.BarcodeTypeError`,
                  :py:exc:`~escpos.exceptions.BarcodeCodeError`
@@ -387,12 +417,19 @@ class Escpos(object):
         bc_types = BARCODE_TYPES[function_type.upper()]
         if bc.upper() not in bc_types.keys():
             raise BarcodeTypeError((
-                "Barcode type '{bc}' not valid for barcode function type "
+                "Barcode '{bc}' not valid for barcode function type "
                 "{function_type}").format(
                     bc=bc,
                     function_type=function_type,
                 ))
 
+        if check and not self.check_barcode(bc, code):
+            raise BarcodeCodeError((
+                "Barcode '{code}' not in a valid format for type '{bc}'").format(
+                code=code,
+                bc=bc,
+            ))
+
         # Align Bar Code()
         if align_ct:
             self._raw(TXT_STYLE['align']['center'])

src/escpos/exceptions.py

@@ -77,9 +77,10 @@ class BarcodeSizeError(Error):
 
 
 class BarcodeCodeError(Error):
-    """ No Barcode code was supplied.
+    """ No Barcode code was supplied, or it is incorrect.
 
-    No data for the barcode has been supplied in :py:meth:`escpos.escpos.Escpos.barcode`.
+    No data for the barcode has been supplied in :py:meth:`escpos.escpos.Escpos.barcode` or the the `check` parameter
+    was True and the check failed.
     The returncode for this exception is `30`.
     """
     def __init__(self, msg=""):

test/test_function_barcode.py

@@ -7,7 +7,7 @@ from __future__ import unicode_literals
 import escpos.printer as printer
 from escpos.constants import BARCODE_TYPE_A, BARCODE_TYPE_B
 from escpos.capabilities import Profile, BARCODE_B
-from escpos.exceptions import BarcodeTypeError
+from escpos.exceptions import BarcodeTypeError, BarcodeCodeError
 import pytest
 
 
@@ -36,3 +36,17 @@ def test_lacks_support(bctype, supports_b):
         instance.barcode('test', bctype)
 
     assert instance.output == b''
+
+
+@pytest.mark.parametrize("bctype,data", [
+    ('EAN13', 'AA'),
+    ('CODE128', '{D2354AA'),
+])
+def test_code_check(bctype, data):
+    """should raise an error if the barcode code is invalid.
+    """
+    instance = printer.Dummy()
+    with pytest.raises(BarcodeCodeError):
+        instance.barcode(data, bctype)
+
+    assert instance.output == b''

test/test_function_check_barcode.py

@@ -0,0 +1,104 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+from __future__ import unicode_literals
+
+import escpos.printer as printer
+import pytest
+
+
+@pytest.mark.parametrize("bctype,data", [
+    ('UPC-A', '01234567890'),
+    ('UPC-A', '012345678905'),
+    ('UPC-E', '01234567'),
+    ('UPC-E', '0123456'),
+    ('UPC-E', '012345678905'),
+    ('EAN13', '0123456789012'),
+    ('EAN13', '012345678901'),
+    ('EAN8', '01234567'),
+    ('EAN8', '0123456'),
+    ('CODE39', 'ABC-1234'),
+    ('CODE39', 'ABC-1234-$$-+A'),
+    ('CODE39', '*WIKIPEDIA*'),
+    ('ITF', '010203040506070809'),
+    ('ITF', '11221133113344556677889900'),
+    ('CODABAR', 'A2030405060B'),
+    ('CODABAR', 'C11221133113344556677889900D'),
+    ('CODABAR', 'D0D'),
+    ('NW7', 'A2030405060B'),
+    ('NW7', 'C11221133113344556677889900D'),
+    ('NW7', 'D0D'),
+    ('CODE93', 'A2030405060B'),
+    ('CODE93', '+:$&23-7@$'),
+    ('CODE93', 'D0D'),
+    ('CODE128', '{A2030405060B'),
+    ('CODE128', '{C+:$&23-7@$'),
+    ('CODE128', '{B0D'),
+    ('GS1-128', '{A2030405060B'),
+    ('GS1-128', '{C+:$&23-7@$'),
+    ('GS1-128', '{B0D'),
+    ('GS1 DATABAR OMNIDIRECTIONAL', '0123456789123'),
+    ('GS1 DATABAR TRUNCATED', '0123456789123'),
+    ('GS1 DATABAR LIMITED', '0123456789123'),
+    ('GS1 DATABAR EXPANDED', '(9A{A20304+-%&06a0B'),
+    ('GS1 DATABAR EXPANDED', '(1 {C+:&23-7%'),
+    ('GS1 DATABAR EXPANDED', '(00000001234567678'),
+])
+def test_check_valid_barcode(bctype, data):
+    assert (printer.Escpos.check_barcode(bctype, data))
+
+
+@pytest.mark.parametrize("bctype,data", [
+    ('UPC-A', '01234567890123'),  # too long
+    ('UPC-A', '0123456789'),  # too short
+    ('UPC-A', '72527273-711'),  # invalid '-'
+    ('UPC-A', 'A12345678901'),  # invalid 'A'
+    ('UPC-E', '01234567890123'),  # too long
+    ('UPC-E', '012345'),  # too short
+    ('UPC-E', '72527-2'),  # invalid '-'
+    ('UPC-E', 'A123456'),  # invalid 'A'
+    ('EAN13', '0123456789'),  # too short
+    ('EAN13', 'A123456789012'),  # invalid 'A'
+    ('EAN13', '012345678901234'),  # too long
+    ('EAN8', '012345'),  # too short
+    ('EAN8', 'A123456789012'),  # invalid 'A'
+    ('EAN8', '012345678901234'),  # too long
+    ('CODE39', 'ALKJ_34'),  # invalid '_'
+    ('CODE39', 'A' * 256),  # too long
+    ('ITF', '010203040'),  # odd length
+    ('ITF', '0' * 256),  # too long
+    ('ITF', 'AB01'),  # invalid 'A'
+    ('CODABAR', '010203040'),  # no start/stop
+    ('CODABAR', '0' * 256),  # too long
+    ('CODABAR', 'AB-01F'),  # invalid 'B'
+    ('NW7', '010203040'),  # no start/stop
+    ('NW7', '0' * 256),  # too long
+    ('NW7', 'AB-01F'),  # invalid 'B'
+    ('CODE93', 'é010203040'),  # invalid 'é'
+    ('CODE93', '0' * 256),  # too long
+    ('CODE128', '010203040'),  # missing leading {
+    ('CODE128', '{D2354AA'),  # second char not between A-C
+    ('CODE128', '0' * 256),  # too long
+    ('GS1-128', '010203040'),  # missing leading {
+    ('GS1-128', '{D2354AA'),  # second char not between A-C
+    ('GS1-128', '0' * 256),  # too long
+    ('GS1 DATABAR OMNIDIRECTIONAL', '01234567891234'),  # too long
+    ('GS1 DATABAR OMNIDIRECTIONAL', '012345678912'),  # too short
+    ('GS1 DATABAR OMNIDIRECTIONAL', '012345678A1234'),  # invalid 'A'
+    ('GS1 DATABAR TRUNCATED', '01234567891234'),  # too long
+    ('GS1 DATABAR TRUNCATED', '012345678912'),  # too short
+    ('GS1 DATABAR TRUNCATED', '012345678A1234'),  # invalid 'A'
+    ('GS1 DATABAR LIMITED', '01234567891234'),  # too long
+    ('GS1 DATABAR LIMITED', '012345678912'),  # too short
+    ('GS1 DATABAR LIMITED', '012345678A1234'),  # invalid 'A'
+    ('GS1 DATABAR LIMITED', '02345678912341'),  # invalid start (should be 01)
+    ('GS1 DATABAR EXPANDED', '010203040'),  # missing leading (
+    ('GS1-128', '(' + ('0' * 256)),  # too long
+    ('GS1 DATABAR EXPANDED', '(a{D2354AA'),  # second char not between 0-9
+    ('GS1 DATABAR EXPANDED', 'IT will fail'),  # first char not '('
+])
+def test_check_invalid_barcode(bctype, data):
+    assert (not printer.Escpos.check_barcode(bctype, data))