Test with dummy downstream package

.github/workflows/ci.yaml

@@ -57,10 +57,6 @@ jobs:
     - name: Install package
       run: python -m pip install -e . downstream_dummy/
 
-    - name: Run mypy
-      if: ${{ matrix.python-version == '3.12' }}
-      run: mypy -p "openff.units"
-
     - name: Run unit tests
       run: |
         if [[ ${{ matrix.openmm }} == false ]]; then
@@ -72,6 +68,16 @@ jobs:
     - name: Run dummy package tests
       run: pytest $PYTEST_ARGS downstream_dummy/tests/
 
+    - name: Run mypy
+      if: ${{ matrix.python-version == '3.12' }}
+      run: mypy -p "openff.units"
+
+    - name: Install, typecheck, and test dummy downstream package
+      run: |
+        python -m pip install -e downstream_dummy/
+        mypy downstream_dummy/
+        pytest $PYTEST_ARGS downstream_dummy/tests/
+
     - name: Run docexamples
       if: ${{ matrix.openmm == 'true' }}
       run: pytest --doctest-modules $PYTEST_ARGS $COV openff --ignore=openff/units/_tests

devtools/conda-envs/test_env.yaml

@@ -16,4 +16,5 @@ dependencies:
   - uncertainties
 
     # Typing
-  - mypy
+  - mypy =1.9
+  - types-setuptools

openff/units/units.pyi

@@ -1,13 +1,20 @@
-from typing import overload
-
 import numpy
 
 class Unit:
     def __init__(self, *args, **kwargs): ...
     def __mul__(self, other: int | float | numpy.ndarray) -> Quantity: ...
+    __rmul__ = __mul__
 
 class Quantity:
     def __init__(self, *args, **kwargs): ...
     def to(self, unit: str | Unit = "dimensionless") -> Quantity: ...
     def to_base_units(self, unit: str | Unit = "dimensionless") -> Quantity: ...
     def is_compatible_with(self, unit: str | Unit) -> bool: ...
+    @property
+    def units(self) -> Unit: ...
+
+    # lists are cast to ndarray
+    def m(self) -> float | int | numpy.ndarray: ...
+    def m_as(self) -> float | int | numpy.ndarray: ...
+
+    magnitude = m