def test_visacomm_query(visa_inst, mocker):
"""Query device."""
mock_query = mocker.patch.object(visa_inst, 'query')
comm = VisaCommunicator(visa_inst)
msg = 'asdf'
comm._query(msg)
mock_query.assert_called_with(msg + comm.terminator)
def test_visacomm_timeout(visa_inst):
"""Set / Get timeout of VISA communicator."""
comm = VisaCommunicator(visa_inst)
comm.timeout = 3
assert comm.timeout == u.Quantity(3, u.s)
comm.timeout = u.Quantity(40000, u.ms)
assert comm.timeout == u.Quantity(40, u.s)
def test_visacomm_sendcmd(visa_inst, mocker):
"""Write to device."""
mock_write = mocker.patch.object(VisaCommunicator, 'write')
comm = VisaCommunicator(visa_inst)
msg = 'asdf'
comm._sendcmd(msg)
mock_write.assert_called_with(msg + comm.terminator)
def test_visacomm_write_raw(visa_inst, mocker):
"""Write raw message to instrument."""
mock_write = mocker.patch.object(visa_inst, 'write_raw')
comm = VisaCommunicator(visa_inst)
msg = b'12345'
comm.write_raw(msg)
mock_write.assert_called_with(msg)
def test_visacomm_terminator_not_single_char(visa_inst):
"""Raise ValueError if terminator longer than one character."""
comm = VisaCommunicator(visa_inst)
with pytest.raises(ValueError) as err:
comm.terminator = "\r\n"
err_msg = err.value.args[0]
assert err_msg == (
"Terminator for VisaCommunicator must only be 1 character long.")
def test_visacomm_close(visa_inst, mocker):
"""Raise an IOError if comms cannot be closed."""
io_error_mock = mocker.Mock()
io_error_mock.side_effect = IOError
mock_close = mocker.patch.object(visa_inst, 'close', io_error_mock)
comm = VisaCommunicator(visa_inst)
comm.close()
mock_close.assert_called() # but error will just pass!
def test_visacomm_read_raw_wrong_size(visa_inst):
"""Raise ValueError if size is invalid."""
comm = VisaCommunicator(visa_inst)
with pytest.raises(ValueError) as err:
comm.read_raw(size=-3)
err_msg = err.value.args[0]
assert err_msg == (
"Must read a positive value of characters, or -1 for all characters.")
def test_visacomm_address(visa_inst):
"""Get / Set instrument address."""
comm = VisaCommunicator(visa_inst)
assert comm.address == visa_inst.resource_name
with pytest.raises(NotImplementedError) as err:
comm.address = "new address"
err_msg = err.value.args[0]
assert err_msg == (
"Changing addresses of a VISA Instrument is not supported.")
def test_visacomm_terminator_not_string(visa_inst):
"""Raise TypeError if terminator is set with non-string character."""
comm = VisaCommunicator(visa_inst)
with pytest.raises(TypeError) as err:
comm.terminator = 42
err_msg = err.value.args[0]
assert err_msg == (
"Terminator for VisaCommunicator must be specified as a single "
"character string.")
def test_visacomm_read_raw(visa_inst, mocker):
"""Read raw data from instrument without size specification."""
comm = VisaCommunicator(visa_inst)
mock_read_raw = mocker.patch.object(visa_inst,
'read_raw',
return_value=b'asdf')
comm.read_raw()
mock_read_raw.assert_called()
assert comm._buf == bytearray()
def test_visacomm_read_raw_size(visa_inst, mocker):
"""Read raw data from instrument with size specification."""
comm = VisaCommunicator(visa_inst)
size = 3
mock_read_bytes = mocker.patch.object(visa_inst,
'read_bytes',
return_value=b'123')
ret_val = comm.read_raw(size=size)
assert ret_val == b'123'
mock_read_bytes.assert_called()
assert comm._buf == bytearray()
def open_visa(cls, resource_name):
"""
Opens an instrument, connecting using the VISA library. Note that
`PyVISA`_ and a VISA implementation must both be present and installed
for this method to function.
:param str resource_name: Name of a VISA resource representing the
given instrument.
:rtype: `Instrument`
:return: Object representing the connected instrument.
.. seealso::
`National Instruments help page on VISA resource names
<http://zone.ni.com/reference/en-XX/help/371361J-01/lvinstio/visa_resource_name_generic/>`_.
.. _PyVISA: http://pyvisa.sourceforge.net/
"""
if visa is None:
raise ImportError("PyVISA is required for loading VISA "
"instruments.")
version = list(map(int, visa.__version__.split(".")))
while len(version) < 3:
version += [0]
if version[0] >= 1 and version[1] >= 6:
ins = visa.ResourceManager().open_resource(resource_name)
else:
ins = visa.instrument(resource_name) #pylint: disable=no-member
return cls(VisaCommunicator(ins))
def test_visacomm_init(visa_inst):
"""Initialize visa communicator."""
comm = VisaCommunicator(visa_inst)
assert comm._conn == visa_inst
assert comm._terminator == "\n"
assert comm._buf == bytearray()
def test_visacomm_seek_not_implemented(visa_inst):
"""Raise NotImplementedError when calling seek."""
comm = VisaCommunicator(visa_inst)
with pytest.raises(NotImplementedError):
comm.seek(42)
def test_visacomm_init_wrong_type():
"""Raise TypeError if not a VISA instrument."""
with pytest.raises(TypeError) as err:
VisaCommunicator(42)
err_msg = err.value.args[0]
assert err_msg == "VisaCommunicator must wrap a VISA Instrument."
def test_visacomm_tell_not_implemented(visa_inst):
"""Raise NotImplementedError when calling tell."""
comm = VisaCommunicator(visa_inst)
with pytest.raises(NotImplementedError):
comm.tell()
def test_visacomm_terminator(visa_inst):
"""Get / Set terminator."""
comm = VisaCommunicator(visa_inst)
comm.terminator = ("\r")
assert comm.terminator == "\r"