Excise openff dependency from openmm testing (#993)

* Excise openff dependency from openmm testing

* Remove commmented out code

* Update src/atomate2/openmm/jobs/base.py

Co-authored-by: Janosh Riebesell <janosh.riebesell@gmail.com>

* Respond to Yanosh PR and fix type of OpenMM Flow

* Fix typo, lint

* Add dataclass tag where needed

---------

Co-authored-by: Janosh Riebesell <janosh.riebesell@gmail.com>

src/atomate2/openmm/flows/core.py

@@ -8,7 +8,7 @@
 from typing import TYPE_CHECKING
 
 from emmet.core.openmm import Calculation, OpenMMInterchange, OpenMMTaskDocument
-from jobflow import Flow, Job, Response
+from jobflow import Flow, Job, Maker, Response
 from monty.json import MontyDecoder, MontyEncoder
 
 from atomate2.openmm.jobs.base import openmm_job
@@ -68,7 +68,7 @@ def collect_outputs(
 
 
 @dataclass
-class OpenMMFlowMaker:
+class OpenMMFlowMaker(Maker):
     """Run a production simulation.
 
     This flexible flow links together any flows of OpenMM jobs in

src/atomate2/openmm/jobs/base.py

@@ -524,6 +524,11 @@ def _update_interchange(
             interchange.box = state.getPeriodicBoxVectors(asNumpy=True)
         elif isinstance(interchange, OpenMMInterchange):
             interchange.state = XmlSerializer.serialize(state)
+        else:
+            raise TypeError(
+                f"Interchange must be an Interchange or "
+                f"OpenMMInterchange object, got {type(interchange).__name__}"
+            )
 
     def _create_structure(
         self, sim: Simulation, prev_task: OpenMMTaskDocument | None = None
@@ -607,8 +612,10 @@ def _create_task_doc(
 
         prev_task = prev_task or OpenMMTaskDocument()
 
-        interchange_json = interchange.json()
-        # interchange_bytes = interchange_json.encode("utf-8")
+        if isinstance(interchange, Interchange):
+            interchange_json = interchange.json()
+        else:
+            interchange_json = interchange.model_dump_json()
 
         return OpenMMTaskDocument(
             tags=tags,

src/atomate2/openmm/utils.py

@@ -2,15 +2,23 @@
 
 from __future__ import annotations
 
+import io
 import re
 import tempfile
 import time
 import warnings
 from pathlib import Path
 from typing import TYPE_CHECKING
 
+import numpy as np
+import openmm.unit as omm_unit
+from emmet.core.openmm import OpenMMInterchange
+from openmm import LangevinMiddleIntegrator, XmlSerializer
+from openmm.app import PDBFile
+
 if TYPE_CHECKING:
     from emmet.core.openmm import OpenMMTaskDocument
+    from openff.interchange import Interchange
 
 
 def download_opls_xml(
@@ -132,3 +140,34 @@ def task_reports(task: OpenMMTaskDocument, traj_or_state: str = "traj") -> bool:
     else:
         raise ValueError("traj_or_state must be 'traj' or 'state'")
     return calc_input.n_steps >= report_freq
+
+
+def openff_to_openmm_interchange(
+    openff_interchange: Interchange,
+) -> OpenMMInterchange:
+    """Convert an OpenFF Interchange object to an OpenMM Interchange object."""
+    integrator = LangevinMiddleIntegrator(
+        300 * omm_unit.kelvin,
+        10.0 / omm_unit.picoseconds,
+        1.0 * omm_unit.femtoseconds,
+    )
+    sim = openff_interchange.to_openmm_simulation(integrator)
+    state = sim.context.getState(
+        getPositions=True,
+        getVelocities=True,
+        enforcePeriodicBox=True,
+    )
+    with io.StringIO() as buffer:
+        PDBFile.writeFile(
+            sim.topology,
+            np.zeros(shape=(sim.topology.getNumAtoms(), 3)),
+            file=buffer,
+        )
+        buffer.seek(0)
+        pdb = buffer.read()
+
+        return OpenMMInterchange(
+            system=XmlSerializer.serialize(sim.system),
+            state=XmlSerializer.serialize(state),
+            topology=pdb,
+        )

tests/openff_md/test_core.py

@@ -1,8 +1,11 @@
+import pytest
 from emmet.core.openff import ClassicalMDTaskDocument, MoleculeSpec
-from openff.interchange import Interchange
 
 from atomate2.openff.core import generate_interchange
 
+pytest.importorskip("openff.toolkit")
+from openff.interchange import Interchange  # noqa: E402
+
 
 def test_generate_interchange(mol_specs_small, run_job):
     mass_density = 1

tests/openff_md/test_utils.py

@@ -1,21 +1,8 @@
 import numpy as np
-import openff.toolkit as tk
 import pymatgen
 import pytest
 from emmet.core.openff import MoleculeSpec
-from openff.interchange import Interchange
-from openff.toolkit.topology import Topology
-from openff.toolkit.topology.molecule import Molecule
-from openff.units import Quantity
 from pymatgen.analysis.graphs import MoleculeGraph
-from pymatgen.io.openff import (
-    add_conformer,
-    assign_partial_charges,
-    create_openff_mol,
-    get_atom_map,
-    infer_openff_mol,
-    mol_graph_to_openff_mol,
-)
 
 from atomate2.openff.utils import (
     counts_from_box_size,
@@ -24,6 +11,21 @@
     merge_specs_by_name_and_smiles,
 )
 
+pytest.importorskip("openff.toolkit")
+import openff.toolkit as tk  # noqa: E402
+from openff.interchange import Interchange  # noqa: E402
+from openff.toolkit.topology import Topology  # noqa: E402
+from openff.toolkit.topology.molecule import Molecule  # noqa: E402
+from openff.units import Quantity  # noqa: E402
+from pymatgen.io.openff import (  # noqa: E402
+    add_conformer,
+    assign_partial_charges,
+    create_openff_mol,
+    get_atom_map,
+    infer_openff_mol,
+    mol_graph_to_openff_mol,
+)
+
 
 def test_molgraph_to_openff_pf6(mol_files):
     """transform a water MoleculeGraph to a OpenFF water molecule"""

tests/openmm_md/conftest.py

@@ -1,12 +1,6 @@
-import openff.toolkit as tk
 import pytest
+from emmet.core.openmm import OpenMMInterchange
 from jobflow import run_locally
-from openff.interchange import Interchange
-from openff.interchange.components._packmol import pack_box
-from openff.toolkit import ForceField
-from openff.units import unit
-
-from atomate2.openff.utils import create_mol_spec, merge_specs_by_name_and_smiles
 
 
 @pytest.fixture
@@ -18,37 +12,62 @@ def run_job(job):
     return run_job
 
 
-@pytest.fixture
+@pytest.fixture(scope="package")
 def openmm_data(test_dir):
     return test_dir / "openmm"
 
 
 @pytest.fixture(scope="package")
-def interchange():
-    o = create_mol_spec("O", 300, charge_method="mmff94")
-    cco = create_mol_spec("CCO", 10, charge_method="mmff94")
-    cco2 = create_mol_spec("CCO", 20, name="cco2", charge_method="mmff94")
-    mol_specs = [o, cco, cco2]
-    mol_specs.sort(
-        key=lambda x: tk.Molecule.from_json(x.openff_mol).to_smiles() + x.name
-    )
-
-    topology = pack_box(
-        molecules=[tk.Molecule.from_json(spec.openff_mol) for spec in mol_specs],
-        number_of_copies=[spec.count for spec in mol_specs],
-        mass_density=0.8 * unit.grams / unit.milliliter,
-    )
-
-    mol_specs = merge_specs_by_name_and_smiles(mol_specs)
-
-    return Interchange.from_smirnoff(
-        force_field=ForceField("openff_unconstrained-2.1.1.offxml"),
-        topology=topology,
-        charge_from_molecules=[
-            tk.Molecule.from_json(spec.openff_mol) for spec in mol_specs
-        ],
-        allow_nonintegral_charges=True,
-    )
+def interchange(openmm_data):
+    # we use openff to generate the interchange object that we test on
+    # but we don't want to create a logical dependency on openff, in
+    # case the user has another way of generating the interchange object
+    regenerate_test_data = False
+    if regenerate_test_data:
+        import openff.toolkit as tk
+        from openff.interchange import Interchange
+        from openff.interchange.components._packmol import pack_box
+        from openff.toolkit import ForceField
+        from openff.units import unit
+
+        from atomate2.openff.utils import (
+            create_mol_spec,
+            merge_specs_by_name_and_smiles,
+        )
+        from atomate2.openmm.utils import openff_to_openmm_interchange
+
+        o = create_mol_spec("O", 300, charge_method="mmff94")
+        cco = create_mol_spec("CCO", 10, charge_method="mmff94")
+        cco2 = create_mol_spec("CCO", 20, name="cco2", charge_method="mmff94")
+        mol_specs = [o, cco, cco2]
+        mol_specs.sort(
+            key=lambda x: tk.Molecule.from_json(x.openff_mol).to_smiles() + x.name
+        )
+
+        topology = pack_box(
+            molecules=[tk.Molecule.from_json(spec.openff_mol) for spec in mol_specs],
+            number_of_copies=[spec.count for spec in mol_specs],
+            mass_density=0.8 * unit.grams / unit.milliliter,
+        )
+
+        mol_specs = merge_specs_by_name_and_smiles(mol_specs)
+
+        openff_interchange = Interchange.from_smirnoff(
+            force_field=ForceField("openff_unconstrained-2.1.1.offxml"),
+            topology=topology,
+            charge_from_molecules=[
+                tk.Molecule.from_json(spec.openff_mol) for spec in mol_specs
+            ],
+            allow_nonintegral_charges=True,
+        )
+
+        openmm_interchange = openff_to_openmm_interchange(openff_interchange)
+
+        with open(openmm_data / "interchange.json", "w") as file:
+            file.write(openmm_interchange.model_dump_json())
+
+    with open(openmm_data / "interchange.json") as file:
+        return OpenMMInterchange.model_validate_json(file.read())
 
 
 @pytest.fixture

tests/openmm_md/flows/test_core.py

@@ -1,15 +1,16 @@
 from __future__ import annotations
 
+import io
 import json
 from pathlib import Path
 
 import numpy as np
 import pytest
-from emmet.core.openmm import OpenMMTaskDocument
+from emmet.core.openmm import OpenMMInterchange, OpenMMTaskDocument
 from jobflow import Flow
 from MDAnalysis import Universe
 from monty.json import MontyDecoder
-from openff.interchange import Interchange
+from openmm.app import PDBFile
 
 from atomate2.openmm.flows.core import OpenMMFlowMaker
 from atomate2.openmm.jobs import EnergyMinimizationMaker, NPTMaker, NVTMaker
@@ -156,22 +157,13 @@ def test_flow_maker(interchange, run_job):
     calc_output = task_doc.calcs_reversed[0].output
     assert len(calc_output.steps_reported) == 5
 
-    all_steps = [calc.output.steps_reported for calc in task_doc.calcs_reversed]
-    assert all_steps == [
-        [1, 2, 3, 4, 5],
-        [1],
-        [1, 2],
-        [1, 2],
-        [1, 2, 3, 4, 5],
-        None,
-    ]
     # Test that the state interval is respected
-    assert calc_output.steps_reported == list(range(1, 6))
+    assert calc_output.steps_reported == list(range(11, 16))
     assert calc_output.traj_file == "trajectory5.dcd"
     assert calc_output.state_file == "state5.csv"
 
-    interchange = Interchange.parse_raw(task_doc.interchange)
-    topology = interchange.to_openmm_topology()
+    interchange = OpenMMInterchange.model_validate_json(task_doc.interchange)
+    topology = PDBFile(io.StringIO(interchange.topology)).getTopology()
     u = Universe(topology, str(Path(task_doc.dir_name) / "trajectory5.dcd"))
 
     assert len(u.trajectory) == 5
@@ -184,8 +176,9 @@ def test_traj_blob_embed(interchange, run_job, tmp_path):
     nvt_job = nvt.make(interchange)
     task_doc = run_job(nvt_job)
 
-    interchange = Interchange.parse_raw(task_doc.interchange)
-    topology = interchange.to_openmm_topology()
+    interchange = OpenMMInterchange.model_validate_json(task_doc.interchange)
+    topology = PDBFile(io.StringIO(interchange.topology)).getTopology()
+
     u = Universe(topology, str(Path(task_doc.dir_name) / "trajectory.dcd"))
 
     assert len(u.trajectory) == 2

tests/openmm_md/jobs/test_base.py

@@ -6,6 +6,7 @@
 from emmet.core.openmm import Calculation, CalculationInput, OpenMMTaskDocument
 from jobflow import Flow, Job
 from mdareporter import MDAReporter
+from openmm import XmlSerializer
 from openmm.app import Simulation, StateDataReporter
 from openmm.openmm import LangevinMiddleIntegrator
 from openmm.unit import kelvin, picoseconds
@@ -70,22 +71,30 @@ def test_create_simulation(interchange):
 def test_update_interchange(interchange):
     interchange = copy.deepcopy(interchange)
     maker = BaseOpenMMMaker(wrap_traj=True)
+
     sim = maker._create_simulation(interchange)  # noqa: SLF001
-    start_positions = interchange.positions
-    start_velocities = interchange.velocities
-    start_box = interchange.box
+
+    state = XmlSerializer.deserialize(interchange.state)
+    start_positions = state.getPositions(asNumpy=True)
+    start_velocities = state.getVelocities(asNumpy=True)
+    start_box = state.getPeriodicBoxVectors()
 
     # Run the simulation for one step
-    sim.step(1)
+    sim.step(2)
 
     maker._update_interchange(interchange, sim, None)  # noqa: SLF001
 
-    assert interchange.positions.shape == start_positions.shape
-    assert interchange.velocities.shape == (1170, 3)
+    new_state = XmlSerializer.deserialize(interchange.state)
+    new_positions = new_state.getPositions(asNumpy=True)
+    new_velocities = new_state.getVelocities(asNumpy=True)
+    new_box = new_state.getPeriodicBoxVectors()
+
+    assert new_positions.shape == start_positions.shape
+    assert new_velocities.shape == start_velocities.shape
 
-    assert np.any(interchange.positions != start_positions)
-    assert np.any(interchange.velocities != start_velocities)
-    assert np.all(interchange.box == start_box)
+    assert not np.all(new_positions == start_positions)
+    assert not np.all(new_velocities == start_velocities)
+    assert np.all(new_box == start_box)
 
 
 def test_create_task_doc(interchange, tmp_path):