Add tools property and entrypoint for workflows

This is an implementation of feature request in issue #6865. It also
includes:
* Fixes the typing hints as `tools` as it can return `None`.
* Add tests for `CalcJobNode.tools` and `WorkChainNode.tools`

Author: agoscinski

src/aiida/orm/nodes/process/calculation/calcjob.py

@@ -106,7 +106,7 @@ class Model(CalculationNode.Model):
     _tools = None
 
     @property
-    def tools(self) -> 'CalculationTools':
+    def tools(self) -> Optional['CalculationTools']:
         """Return the calculation tools that are registered for the process type associated with this calculation.
 
         If the entry point name stored in the `process_type` of the CalcJobNode has an accompanying entry point in the

src/aiida/orm/nodes/process/workflow/workchain.py

@@ -8,12 +8,16 @@
 ###########################################################################
 """Module with `Node` sub class for workchain processes."""
 
-from typing import Optional, Tuple
+from typing import TYPE_CHECKING, Optional, Tuple
 
+from aiida.common import exceptions
 from aiida.common.lang import classproperty
 
 from .workflow import WorkflowNode
 
+if TYPE_CHECKING:
+    from aiida.tools.workflows import WorkflowTools
+
 __all__ = ('WorkChainNode',)
 
 
@@ -22,6 +26,40 @@ class WorkChainNode(WorkflowNode):
 
     STEPPER_STATE_INFO_KEY = 'stepper_state_info'
 
+    # An optional entry point for a CalculationTools instance
+    _tools = None
+
+    @property
+    def tools(self) -> Optional['WorkflowTools']:
+        """Return the calculation tools that are registered for the process type associated with this calculation.
+
+        If the entry point name stored in the `process_type` of the CalcJobNode has an accompanying entry point in the
+        `aiida.tools.calculations` entry point category, it will attempt to load the entry point and instantiate it
+        passing the node to the constructor. If the entry point does not exist, cannot be resolved or loaded, a warning
+        will be logged and the base CalculationTools class will be instantiated and returned.
+
+        :return: CalculationTools instance
+        """
+        from aiida.plugins.entry_point import get_entry_point_from_string, is_valid_entry_point_string, load_entry_point
+        from aiida.tools.workflows import WorkflowTools
+
+        if self._tools is None:
+            entry_point_string = self.process_type
+
+            if entry_point_string and is_valid_entry_point_string(entry_point_string):
+                entry_point = get_entry_point_from_string(entry_point_string)
+
+                try:
+                    tools_class = load_entry_point('aiida.tools.workflows', entry_point.name)
+                    self._tools = tools_class(self)
+                except exceptions.EntryPointError as exception:
+                    self._tools = WorkflowTools(self)
+                    self.logger.warning(
+                        f'could not load the workflow tools entry point {entry_point.name}: {exception}'
+                    )
+
+        return self._tools
+
     @classproperty
     def _updatable_attributes(cls) -> Tuple[str, ...]:  # type: ignore[override]  # noqa: N805
         return super()._updatable_attributes + (cls.STEPPER_STATE_INFO_KEY,)

src/aiida/tools/workflows/__init__.py

@@ -0,0 +1,21 @@
+###########################################################################
+# Copyright (c), The AiiDA team. All rights reserved.                     #
+# This file is part of the AiiDA code.                                    #
+#                                                                         #
+# The code is hosted on GitHub at https://github.com/aiidateam/aiida-core #
+# For further information on the license, see the LICENSE.txt file        #
+# For further information please visit http://www.aiida.net               #
+###########################################################################
+"""Workflow tool plugins for Workflow classes."""
+
+# AUTO-GENERATED
+
+# fmt: off
+
+from .base import *
+
+__all__ = (
+    'WorkflowTools',
+)
+
+# fmt: on

src/aiida/tools/workflows/base.py

@@ -0,0 +1,22 @@
+###########################################################################
+# Copyright (c), The AiiDA team. All rights reserved.                     #
+# This file is part of the AiiDA code.                                    #
+#                                                                         #
+# The code is hosted on GitHub at https://github.com/aiidateam/aiida-core #
+# For further information on the license, see the LICENSE.txt file        #
+# For further information please visit http://www.aiida.net               #
+###########################################################################
+"""Base class for WorkflowTools
+
+Sub-classes can be registered in the `aiida.tools.calculations` category to enable the `CalcJobNode` class from being
+able to find the tools plugin, load it and expose it through the `tools` property of the `CalcJobNode`.
+"""
+
+__all__ = ('WorkflowTools',)
+
+
+class WorkflowTools:
+    """Base class for WorkflowTools."""
+
+    def __init__(self, node):
+        self._node = node

tests/tools/calculations/__init__.py

@@ -0,0 +1,8 @@
+###########################################################################
+# Copyright (c), The AiiDA team. All rights reserved.                     #
+# This file is part of the AiiDA code.                                    #
+#                                                                         #
+# The code is hosted on GitHub at https://github.com/aiidateam/aiida-core #
+# For further information on the license, see the LICENSE.txt file        #
+# For further information please visit http://www.aiida.net               #
+###########################################################################

tests/tools/calculations/test_base.py

@@ -0,0 +1,33 @@
+###########################################################################
+# Copyright (c), The AiiDA team. All rights reserved.                     #
+# This file is part of the AiiDA code.                                    #
+#                                                                         #
+# The code is hosted on GitHub at https://github.com/aiidateam/aiida-core #
+# For further information on the license, see the LICENSE.txt file        #
+# For further information please visit http://www.aiida.net               #
+###########################################################################
+"""Tests for GroupPath"""
+
+
+class MockCalculationTools:
+    def __init__(self, node):
+        self._node = node
+        self._mock = True
+
+
+def test_mock_calculation_tools(entry_points, generate_calcjob_node):
+    """Test if the calculation tools is correctly loaded from the entry point."""
+    entry_points.add(MockCalculationTools, 'aiida.tools.calculations:MockCalculationTools')
+    node = generate_calcjob_node(entry_point='aiida.tools.calculations:MockCalculationTools')
+    assert node.tools._node == node
+    assert node.tools._mock
+
+
+def test_failback_calculation_tools(entry_points, generate_calcjob_node):
+    """Test if the calculation tools is falling back to `CalculationTools` if it cannot be loaded from entry point."""
+    from aiida.tools.calculations import CalculationTools
+
+    entry_points.add('DoesNotExist', 'aiida.tools.calculations:MockCalculationTools')
+    node = generate_calcjob_node(entry_point='aiida.tools.calculations:MockCalculationTools')
+    assert isinstance(node.tools, CalculationTools)
+    assert node.tools._node == node

tests/tools/workflows/__init__.py

@@ -0,0 +1,8 @@
+###########################################################################
+# Copyright (c), The AiiDA team. All rights reserved.                     #
+# This file is part of the AiiDA code.                                    #
+#                                                                         #
+# The code is hosted on GitHub at https://github.com/aiidateam/aiida-core #
+# For further information on the license, see the LICENSE.txt file        #
+# For further information please visit http://www.aiida.net               #
+###########################################################################

tests/tools/workflows/test_base.py

@@ -0,0 +1,33 @@
+###########################################################################
+# Copyright (c), The AiiDA team. All rights reserved.                     #
+# This file is part of the AiiDA code.                                    #
+#                                                                         #
+# The code is hosted on GitHub at https://github.com/aiidateam/aiida-core #
+# For further information on the license, see the LICENSE.txt file        #
+# For further information please visit http://www.aiida.net               #
+###########################################################################
+"""Tests for GroupPath"""
+
+
+class MockWorkflowTools:
+    def __init__(self, node):
+        self._node = node
+        self._mock = True
+
+
+def test_mock_calculation_tools(entry_points, generate_work_chain):
+    """Test if the calculation tools is correctly loaded from the entry point."""
+    entry_points.add(MockWorkflowTools, 'aiida.tools.workflows:MockWorkflowTools')
+    node = generate_work_chain(entry_point='aiida.tools.workflows:MockWorkflowTools')
+    assert node.tools._node == node
+    assert node.tools._mock
+
+
+def test_failback_calculation_tools(entry_points, generate_calcjob_node):
+    """Test if the calculation tools is falling back to `WorkflowTools` if it cannot be loaded from entry point."""
+    from aiida.tools.workflows import WorkflowTools
+
+    entry_points.add('DoesNotExist', 'aiida.tools.workflows:MockWorkflowTools')
+    node = generate_calcjob_node(entry_point='aiida.tools.workflows:MockWorkflowTools')
+    assert isinstance(node.tools, WorkflowTools)
+    assert node.tools._node == node