fix: sonar complaint about timestamp (#2152)

* fix: sonar complaint re: _timestamp

Move this time-dependent expression out of the class body and into a
method.

Signed-off-by: degenaro <lou.degenaro@gmail.com>

* fix: get_timestamp

Signed-off-by: degenaro <lou.degenaro@gmail.com>

* fix: don't duplicate code

Signed-off-by: degenaro <lou.degenaro@gmail.com>

* fix: formatting

Signed-off-by: degenaro <lou.degenaro@gmail.com>

* fix: run hatch version

Signed-off-by: degenaro <lou.degenaro@gmail.com>

* fix: workflow caching issues

Signed-off-by: degenaro <lou.degenaro@gmail.com>

* undo npm change

Signed-off-by: degenaro <lou.degenaro@gmail.com>

* fix hatch cache issue

Signed-off-by: degenaro <lou.degenaro@gmail.com>

* fix hatch caching issue

Signed-off-by: degenaro <lou.degenaro@gmail.com>

---------

Signed-off-by: degenaro <lou.degenaro@gmail.com>

Author: degenaro

.github/workflows/python-test.yml

@@ -141,6 +141,11 @@ jobs:
     - name: Install hatch
       run: |
         make develop
+    - name: Recreate hatch test environment
+      shell: bash
+      run: |
+        hatch env remove hatch-test.py${{ matrix.python-version }} 2>/dev/null || true
+        hatch env create hatch-test.py${{ matrix.python-version }}
     - name: gen OSCAL models
       run: |
         make gen-oscal
@@ -195,6 +200,11 @@ jobs:
     - name: Install hatch
       run: |
         pip install hatch "virtualenv>=20.26.6,<21"  # Pin until hatch supports virtualenv 21.x
+    - name: Recreate hatch test environment
+      shell: bash
+      run: |
+        hatch env remove hatch-test.py${{ matrix.python-version }} 2>/dev/null || true
+        hatch env create hatch-test.py${{ matrix.python-version }}
     - name: Run tests
       if: steps.core-version.outputs.core != 'true'
       run: |

trestle/transforms/transformer_factory.py

@@ -28,7 +28,11 @@ class TransformerBase(ABC):
     """Abstract base interface for all transformers."""
 
     # the current time for consistent timestamping
-    _timestamp = datetime.datetime.now(datetime.timezone.utc).replace(microsecond=0).isoformat()
+    _timestamp = None
+
+    def __init__(self) -> None:
+        """Initialize the transformer and set timestamp if not already set."""
+        TransformerBase.get_timestamp()
 
     @staticmethod
     def set_timestamp(value: str) -> None:
@@ -39,6 +43,8 @@ def set_timestamp(value: str) -> None:
     @staticmethod
     def get_timestamp() -> str:
         """Get the default timestamp value."""
+        if TransformerBase._timestamp is None:
+            TransformerBase._timestamp = datetime.datetime.now(datetime.timezone.utc).replace(microsecond=0).isoformat()
         return TransformerBase._timestamp
 
     @abstractmethod