Ensure no unexpected warnings are emitted during test suite runs

Removing the -W ignore flag in #1362 caused warnings emitted during pytest run to be shown again (see below for a list)
Ideally, this list would be empty:
- Expected warnings should be inspected within the testing code using pytest.warns() (which as I understand is equivalent to pytest.raises() used for exceptions)
- Unexpected warnings should be addressed in the code being tested

General strategies

`SyntaxWarning` invalid escape sequence

Most often found in pytest.raises(match=expected_str):
If expected_str is supposed to be a plain string (i.e. containing no regexes), use re.escape()
If expected_str contains both regex constructs and regex symbols that should not be interpreted as regexes, define expected_str as raw literals using r"...", e.g. r"[a-z]+.my_dict\[key\]"

`PytestCollectionWarning`: cannot collect test class 'TestXYZ' because it has a init constructor

If the TestXYZ class is supposed to be a pytest test class (i.e. its methods should be collected as pytest test functions), remove the __init__() definition
If the TestXYZ class is not supposed to be a pytest class, change its name so that it doesn't collide with the Test prefix used by pytest, e.g.
- SampleXYZ
- XYZForTesting

`PytestReturnNotNoneWarning`: Expected `None`, but `<test-function>` returned `<object>`, which will be an error in a future version of pytest. Did you mean to use `assert` instead of `return`?

Test functions in pytest are not supposed to be called directly
Basically all the tests in idaes/apps/matopt have this

idaes/apps/grid_integration/tests/util.py:25
  /home/runner/work/idaes-pse/idaes-pse/idaes/apps/grid_integration/tests/util.py:25: PytestCollectionWarning: cannot collect test class 'TestingModel' because it has a __init__ constructor (from: idaes/apps/grid_integration/tests/test_bidder.py)
    class TestingModel:
idaes/apps/grid_integration/tests/util.py:267
  /home/runner/work/idaes-pse/idaes-pse/idaes/apps/grid_integration/tests/util.py:267: PytestCollectionWarning: cannot collect test class 'TestingForecaster' because it has a __init__ constructor (from: idaes/apps/grid_integration/tests/test_bidder.py)
    class TestingForecaster(AbstractPrescientPriceForecaster):
idaes/apps/grid_integration/tests/test_bidder.py:25
  /home/runner/work/idaes-pse/idaes-pse/idaes/apps/grid_integration/tests/test_bidder.py:25: PytestCollectionWarning: cannot collect test class 'TestMissingModel' because it has a __init__ constructor (from: idaes/apps/grid_integration/tests/test_bidder.py)
    class TestMissingModel:
idaes/apps/grid_integration/tests/util.py:25
  /home/runner/work/idaes-pse/idaes-pse/idaes/apps/grid_integration/tests/util.py:25: PytestCollectionWarning: cannot collect test class 'TestingModel' because it has a __init__ constructor (from: idaes/apps/grid_integration/tests/test_coordinator.py)
    class TestingModel:
idaes/apps/grid_integration/tests/util.py:267
  /home/runner/work/idaes-pse/idaes-pse/idaes/apps/grid_integration/tests/util.py:267: PytestCollectionWarning: cannot collect test class 'TestingForecaster' because it has a __init__ constructor (from: idaes/apps/grid_integration/tests/test_coordinator.py)
    class TestingForecaster(AbstractPrescientPriceForecaster):
idaes/apps/grid_integration/tests/util.py:25
  /home/runner/work/idaes-pse/idaes-pse/idaes/apps/grid_integration/tests/util.py:25: PytestCollectionWarning: cannot collect test class 'TestingModel' because it has a __init__ constructor (from: idaes/apps/grid_integration/tests/test_tracker.py)
    class TestingModel:
idaes/apps/grid_integration/tests/test_tracker.py:19
  /home/runner/work/idaes-pse/idaes-pse/idaes/apps/grid_integration/tests/test_tracker.py:19: PytestCollectionWarning: cannot collect test class 'TestMissingModel' because it has a __init__ constructor (from: idaes/apps/grid_integration/tests/test_tracker.py)
    class TestMissingModel:
idaes/apps/matopt/opt/pyomo_modeling.py:1465
  /home/runner/work/idaes-pse/idaes-pse/idaes/apps/matopt/../matopt/opt/pyomo_modeling.py:1465: SyntaxWarning: "is not" with 'int' literal. Did you mean "!="?
    if PosZic is not 0:
idaes/apps/matopt/opt/pyomo_modeling.py:1469
  /home/runner/work/idaes-pse/idaes-pse/idaes/apps/matopt/../matopt/opt/pyomo_modeling.py:1469: SyntaxWarning: "is not" with 'int' literal. Did you mean "!="?
    if NegZic is not 0:
idaes/apps/matopt/opt/pyomo_modeling.py:1587
  /home/runner/work/idaes-pse/idaes-pse/idaes/apps/matopt/../matopt/opt/pyomo_modeling.py:1587: SyntaxWarning: "is not" with 'int' literal. Did you mean "!="?
    if PosZic is not 0:
idaes/apps/matopt/opt/pyomo_modeling.py:1591
  /home/runner/work/idaes-pse/idaes-pse/idaes/apps/matopt/../matopt/opt/pyomo_modeling.py:1591: SyntaxWarning: "is not" with 'int' literal. Did you mean "!="?
    if NegZic is not 0:
<frozen importlib._bootstrap>:530: 10 warnings
  <frozen importlib._bootstrap>:530: DeprecationWarning: the load_module() method is deprecated and slated for removal in Python 3.12; use exec_module() instead
idaes/core/util/env_info.py:22
  /home/runner/work/idaes-pse/idaes-pse/idaes/core/util/env_info.py:22: DeprecationWarning: pkg_resources is deprecated as an API. See https://setuptools.pypa.io/en/latest/pkg_resources.html
    import pkg_resources
../../../../../usr/share/miniconda/envs/idaes-pse-dev/lib/python3.12/site-packages/pkg_resources/__init__.py:2871
../../../../../usr/share/miniconda/envs/idaes-pse-dev/lib/python3.12/site-packages/pkg_resources/__init__.py:2871
  /usr/share/miniconda/envs/idaes-pse-dev/lib/python3.12/site-packages/pkg_resources/__init__.py:2871: DeprecationWarning: Deprecated call to `pkg_resources.declare_namespace('sphinxcontrib')`.
  Implementing implicit namespace packages (as specified in PEP 420) is preferred to `pkg_resources.declare_namespace`. See https://setuptools.pypa.io/en/latest/references/keywords.html#keyword-namespace-packages
    declare_namespace(pkg)
idaes/core/base/tests/test_components.py:88
  /home/runner/work/idaes-pse/idaes-pse/idaes/core/base/tests/test_components.py:88: SyntaxWarning: invalid escape sequence '\('
    "support is_solute\(\) method. Use a Solvent or "
idaes/core/base/tests/test_components.py:98
  /home/runner/work/idaes-pse/idaes-pse/idaes/core/base/tests/test_components.py:98: SyntaxWarning: invalid escape sequence '\('
    "support is_solvent\(\) method. Use a Solvent or "
idaes/core/base/tests/test_control_volume_1d.py:421
  /home/runner/work/idaes-pse/idaes-pse/idaes/core/base/tests/test_control_volume_1d.py:421: SyntaxWarning: invalid escape sequence '\('
    match="fs.cv length_var must be a scalar \(unindexed\) component.",
idaes/core/base/tests/test_control_volume_1d.py:2314
  /home/runner/work/idaes-pse/idaes-pse/idaes/core/base/tests/test_control_volume_1d.py:2314: SyntaxWarning: invalid escape sequence '\('
    "list of inherent reactions \(inherent_reaction_idx\), "
idaes/core/base/tests/test_flowsheet_model.py:225
  /home/runner/work/idaes-pse/idaes-pse/idaes/core/base/tests/test_flowsheet_model.py:225: SyntaxWarning: invalid escape sequence '\('
    "least two values \(start and end\).",
idaes/core/base/tests/test_property_meta.py:31
  /home/runner/work/idaes-pse/idaes-pse/idaes/core/base/tests/test_property_meta.py:31: SyntaxWarning: invalid escape sequence '\('
    match="Unrecognized units of measurement for quantity TIME \(foo\)",
idaes/core/base/tests/test_property_meta.py:41
  /home/runner/work/idaes-pse/idaes-pse/idaes/core/base/tests/test_property_meta.py:41: SyntaxWarning: invalid escape sequence '\('
    match="Invalid units of measurement for quantity LENGTH \(s\). "
idaes/core/base/tests/test_property_meta.py:52
  /home/runner/work/idaes-pse/idaes-pse/idaes/core/base/tests/test_property_meta.py:52: SyntaxWarning: invalid escape sequence '\('
    match="Invalid units of measurement for quantity MASS \(m\). "
idaes/core/base/tests/test_property_meta.py:63
  /home/runner/work/idaes-pse/idaes-pse/idaes/core/base/tests/test_property_meta.py:63: SyntaxWarning: invalid escape sequence '\('
    match="Invalid units of measurement for quantity AMOUNT \(m\). "
idaes/core/base/tests/test_property_meta.py:74
  /home/runner/work/idaes-pse/idaes-pse/idaes/core/base/tests/test_property_meta.py:74: SyntaxWarning: invalid escape sequence '\('
    match="Invalid units of measurement for quantity TEMPERATURE \(m\). "
idaes/core/base/tests/test_property_meta.py:85
  /home/runner/work/idaes-pse/idaes-pse/idaes/core/base/tests/test_property_meta.py:85: SyntaxWarning: invalid escape sequence '\('
    match="Invalid units of measurement for quantity CURRENT \(m\). "
idaes/core/base/tests/test_property_meta.py:96
  /home/runner/work/idaes-pse/idaes-pse/idaes/core/base/tests/test_property_meta.py:96: SyntaxWarning: invalid escape sequence '\('
    match="Invalid units of measurement for quantity LUMINOUS_INTENSITY \(m\). "
idaes/core/base/tests/test_property_meta.py:107
  /home/runner/work/idaes-pse/idaes-pse/idaes/core/base/tests/test_property_meta.py:107: SyntaxWarning: invalid escape sequence '\('
    match="Invalid units of measurement for quantity TIME \(m\). "
idaes/core/base/tests/test_unit_model.py:201
  /home/runner/work/idaes-pse/idaes-pse/idaes/core/base/tests/test_unit_model.py:201: SyntaxWarning: invalid escape sequence '\('
    "instance of a StateBlock object \(does not have a build_port method\).",
idaes/core/base/tests/test_unit_model.py:322
  /home/runner/work/idaes-pse/idaes-pse/idaes/core/base/tests/test_unit_model.py:322: SyntaxWarning: invalid escape sequence '\('
    " but no default ControlVolume exists \(control_volume\). "
idaes/core/base/tests/test_unit_model.py:530
  /home/runner/work/idaes-pse/idaes-pse/idaes/core/base/tests/test_unit_model.py:530: SyntaxWarning: invalid escape sequence '\('
    "\(control_volume\). Please provide block to which the "
idaes/core/base/tests/test_var_like_expression.py:40
  /home/runner/work/idaes-pse/idaes-pse/idaes/core/base/tests/test_var_like_expression.py:40: SyntaxWarning: invalid escape sequence '\('
    "attribute. Use the 'value\(\)' method instead.",
idaes/core/base/tests/test_var_like_expression.py:118
  /home/runner/work/idaes-pse/idaes-pse/idaes/core/base/tests/test_var_like_expression.py:118: SyntaxWarning: invalid escape sequence '\['
idaes/models/control/tests/test_antiwindup.py::test_setpoint_change_windup
  /usr/share/miniconda/envs/idaes-pse-dev/lib/python3.12/site-packages/_pytest/python.py:198: PytestReturnNotNoneWarning: Expected None, but idaes/models/control/tests/test_antiwindup.py::test_setpoint_change_windup returned (<pyomo.core.base.PyomoModel.ConcreteModel object at 0x7f479e799270>, <pyomo.solvers.plugins.solvers.IPOPT.IPOPT object at 0x7f479dbd36e0>, <idaes.core.solvers.petsc.PetscTrajectory object at 0x7f47a0652660>), which will be an error in a future version of pytest.  Did you mean to use `assert` instead of `return`?
    warnings.warn(
idaes/models/control/tests/test_antiwindup.py::test_setpoint_change_conditional_integration
  /usr/share/miniconda/envs/idaes-pse-dev/lib/python3.12/site-packages/_pytest/python.py:198: PytestReturnNotNoneWarning: Expected None, but idaes/models/control/tests/test_antiwindup.py::test_setpoint_change_conditional_integration returned (<pyomo.core.base.PyomoModel.ConcreteModel object at 0x7f479dfb8910>, <pyomo.solvers.plugins.solvers.IPOPT.IPOPT object at 0x7f479f16d880>, <idaes.core.solvers.petsc.PetscTrajectory object at 0x7f479e2ff410>), which will be an error in a future version of pytest.  Did you mean to use `assert` instead of `return`?
    warnings.warn(
idaes/models/control/tests/test_antiwindup.py::test_setpoint_change_back_calculation
  /usr/share/miniconda/envs/idaes-pse-dev/lib/python3.12/site-packages/_pytest/python.py:198: PytestReturnNotNoneWarning: Expected None, but idaes/models/control/tests/test_antiwindup.py::test_setpoint_change_back_calculation returned (<pyomo.core.base.PyomoModel.ConcreteModel object at 0x7f479f5e14f0>, <pyomo.solvers.plugins.solvers.IPOPT.IPOPT object at 0x7f47a0ad28d0>, <idaes.core.solvers.petsc.PetscTrajectory object at 0x7f479cb69a60>), which will be an error in a future version of pytest.  Did you mean to use `assert` instead of `return`?
    warnings.warn(
idaes/models_extra/power_generation/costing/tests/test_CCS_capcost.py::test_ccs_units_costing
  /usr/share/miniconda/envs/idaes-pse-dev/lib/python3.12/site-packages/_pytest/python.py:198: PytestReturnNotNoneWarning: Expected None, but idaes/models_extra/power_generation/costing/tests/test_CCS_capcost.py::test_ccs_units_costing returned <pyomo.core.base.PyomoModel.ConcreteModel object at 0x7f479b857250>, which will be an error in a future version of pytest.  Did you mean to use `assert` instead of `return`?
    warnings.warn(
idaes/models_extra/power_generation/costing/tests/test_power_plant_capcost.py::test_PP_costing
  /usr/share/miniconda/envs/idaes-pse-dev/lib/python3.12/site-packages/_pytest/python.py:198: PytestReturnNotNoneWarning: Expected None, but idaes/models_extra/power_generation/costing/tests/test_power_plant_capcost.py::test_PP_costing returned <pyomo.core.base.PyomoModel.ConcreteModel object at 0x7f479ba7f7a0>, which will be an error in a future version of pytest.  Did you mean to use `assert` instead of `return`?
    warnings.warn(
idaes/models_extra/power_generation/costing/tests/test_power_plant_capcost.py::test_power_plant_costing
  /usr/share/miniconda/envs/idaes-pse-dev/lib/python3.12/site-packages/_pytest/python.py:198: PytestReturnNotNoneWarning: Expected None, but idaes/models_extra/power_generation/costing/tests/test_power_plant_capcost.py::test_power_plant_costing returned <pyomo.core.base.PyomoModel.ConcreteModel object at 0x7f47a45eb1b0>, which will be an error in a future version of pytest.  Did you mean to use `assert` instead of `return`?
    warnings.warn(
idaes/models_extra/power_generation/costing/tests/test_power_plant_capcost.py::test_sCO2_costing
  /usr/share/miniconda/envs/idaes-pse-dev/lib/python3.12/site-packages/_pytest/python.py:198: PytestReturnNotNoneWarning: Expected None, but idaes/models_extra/power_generation/costing/tests/test_power_plant_capcost.py::test_sCO2_costing returned <pyomo.core.base.PyomoModel.ConcreteModel object at 0x7f479ebda710>, which will be an error in a future version of pytest.  Did you mean to use `assert` instead of `return`?
    warnings.warn(
idaes/models_extra/power_generation/costing/tests/test_power_plant_capcost.py::test_ASU_costing
  /usr/share/miniconda/envs/idaes-pse-dev/lib/python3.12/site-packages/_pytest/python.py:198: PytestReturnNotNoneWarning: Expected None, but idaes/models_extra/power_generation/costing/tests/test_power_plant_capcost.py::test_ASU_costing returned <pyomo.core.base.PyomoModel.ConcreteModel object at 0x7f479ed1bc50>, which will be an error in a future version of pytest.  Did you mean to use `assert` instead of `return`?
    warnings.warn(
idaes/models_extra/power_generation/unit_models/helm/tests/test_turbine_multistage.py::test_initialize
  /usr/share/miniconda/envs/idaes-pse-dev/lib/python3.12/site-packages/_pytest/python.py:198: PytestReturnNotNoneWarning: Expected None, but idaes/models_extra/power_generation/unit_models/helm/tests/test_turbine_multistage.py::test_initialize returned <pyomo.core.base.PyomoModel.ConcreteModel object at 0x7f47834d1fe0>, which will be an error in a future version of pytest.  Did you mean to use `assert` instead of `return`?
    warnings.warn(
idaes/models_extra/power_generation/unit_models/helm/tests/test_turbine_multistage.py::test_initialize_calc_cf
  /usr/share/miniconda/envs/idaes-pse-dev/lib/python3.12/site-packages/_pytest/python.py:198: PytestReturnNotNoneWarning: Expected None, but idaes/models_extra/power_generation/unit_models/helm/tests/test_turbine_multistage.py::test_initialize_calc_cf returned <pyomo.core.base.PyomoModel.ConcreteModel object at 0x7f479dc1f750>, which will be an error in a future version of pytest.  Did you mean to use `assert` instead of `return`?
    warnings.warn(
idaes/tests/prescient/test_prescient.py::Test5Bus::test_data_path_available
idaes/tests/prescient/test_prescient.py::Test5Bus::test_simulation_results
  /home/runner/work/idaes-pse/idaes-pse/idaes/tests/prescient/test_prescient.py:36: DeprecationWarning: path is deprecated. Use files() instead. Refer to https://importlib-resources.readthedocs.io/en/latest/using.html#migrating-from-legacy for migration advice.
    with resources.path("idaes.tests.prescient.5bus", "__init__.py") as pkg_file:

Example from

idaes-pse/idaes/core/base/tests/test_var_like_expression.py

Lines 37 to 42 in bc2f6c0

    
           with pytest.raises( 
        
               TypeError, 
        
               match="e is an Expression and does not have a value " 
        
               "attribute. Use the 'value\(\)' method instead.", 
        
           ): 
        
               assert m.e.value == 42

import re
...
    with pytest.raises(
        TypeError,
        match=re.escape(
            "e is an Expression and does not have a value "
            "attribute. Use the 'value()' method instead."
        ),
    ):
        assert m.e.value == 42

	with pytest.raises(
	TypeError,
	match="e is an Expression and does not have a value "
	"attribute. Use the 'value\(\)' method instead.",
	):
	assert m.e.value == 42

General strategies

SyntaxWarning invalid escape sequence

PytestCollectionWarning: cannot collect test class 'TestXYZ' because it has a init constructor

PytestReturnNotNoneWarning: Expected None, but <test-function> returned <object>, which will be an error in a future version of pytest. Did you mean to use assert instead of return?

`SyntaxWarning` invalid escape sequence

`PytestCollectionWarning`: cannot collect test class 'TestXYZ' because it has a init constructor

`PytestReturnNotNoneWarning`: Expected `None`, but `<test-function>` returned `<object>`, which will be an error in a future version of pytest. Did you mean to use `assert` instead of `return`?