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Improve and extend the _read() method availability for its users and related methods. Part 4: Implement _read() in Dummy() #714

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Improve and extend the _read() method availability for its users and related methods. Part 4: Implement _read() in Dummy() #714

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e2e52c9
Implement _read() into the Dummy() connector
belono Oct 8, 2025
f388f6a
Fix _read() return value
belono Oct 20, 2025
b7693d4
Add tests for the dummy printer to the tests battery
belono Oct 20, 2025
82cdd94
Remove test_function_dummy.py
belono Oct 20, 2025
da86a28
Fix trailing whitespace
belono Oct 20, 2025
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6 changes: 6 additions & 0 deletions src/escpos/printer/dummy.py
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Original file line number Diff line number Diff line change
Expand Up @@ -52,6 +52,12 @@ def _raw(self, msg: bytes) -> None:
"""
self._output_list.append(msg)

def _read(self) -> bytes:
"""Read the last byte of data and return it to the caller."""
if not self._output_list:
return b""
return bytes([self._output_list[-1][-1]])

@property
def output(self) -> bytes:
"""Get the data that was sent to this printer."""
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8 changes: 0 additions & 8 deletions test/test_functions/test_function_dummy_clear.py
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42 changes: 42 additions & 0 deletions test/test_printers/test_printer_dummy.py
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Original file line number Diff line number Diff line change
@@ -0,0 +1,42 @@
#!/usr/bin/python
# -*- coding: utf-8 -*-
"""tests for the Dummy printer

:author: Benito López and the python-escpos developers
:organization: `python-escpos <https://github.com/python-escpos>`_
:copyright: Copyright (c) 2025 `python-escpos <https://github.com/python-escpos>`_
:license: MIT
"""


def test_clear(driver) -> None:
"""
GIVEN a dummy printer object
WHEN clear method is called
THEN check the return value is the expected
"""
driver.text("Hello")
driver.clear()
assert driver.output == b""


def test_read_no_output(driver) -> None:
"""
GIVEN a dummy printer object with no output data
WHEN reading the last byte of data
THEN check the return value is the expected
"""
driver.clear()
assert driver._read() == b""


def test_read(driver) -> None:
"""
GIVEN a dummy printer object
WHEN reading the last byte of data
THEN check the return value is the expected
"""
driver._raw(b"\x10\x04\x01") # RT_STATUS_ONLINE
assert driver._read() == b"\x01"
driver._raw(b"\x12") # Simulate an 'is online' response
assert driver._read() == b"\x12"