Merge pull request #909 from openforcefield/json-roundtrip-bugfixes

Do not ignore float/int in JSON input

docs/releasehistory.md

@@ -11,6 +11,10 @@ Dates are given in YYYY-MM-DD format.
 
 Please note that all releases prior to a version 1.0.0 are considered pre-releases and many API changes will come before a stable release.
 
+## Current development
+
+* #909 Fixes a bug in which numerical values such as `scale_14` were lost when parsing JSON dumps.
+
 ## 0.3.21 - 2023-02-20
 
 * #906 Fixes a bug in which intramolecular interactions between virtual sites were not properly excluded with OpenMM.

openff/interchange/_tests/energy_tests/smirnoff/__init__.py

@@ -0,0 +1 @@
+"""Energy tests directly related to the SMIRNOFF submodule."""

openff/interchange/_tests/energy_tests/smirnoff/test_base.py

@@ -0,0 +1,27 @@
+from openff.toolkit import Quantity
+from openff.utilities.testing import skip_if_missing
+
+from openff.interchange import Interchange
+from openff.interchange._tests import MoleculeWithConformer, needs_gmx
+from openff.interchange.drivers import get_gromacs_energies, get_openmm_energies
+
+
+@needs_gmx
+@skip_if_missing("openmm")
+def test_issue_908(sage_unconstrained):
+    molecule = MoleculeWithConformer.from_smiles("ClCCl")
+    topology = molecule.to_topology()
+    topology.box_vectors = Quantity([4, 4, 4], "nanometer")
+
+    state1 = sage_unconstrained.create_interchange(topology)
+
+    with open("test.json", "w") as f:
+        f.write(state1.json())
+
+    state2 = Interchange.parse_file("test.json")
+
+    get_gromacs_energies(state1).compare(get_gromacs_energies(state2))
+    get_openmm_energies(
+        state1,
+        combine_nonbonded_forces=False,
+    ).compare(get_openmm_energies(state2, combine_nonbonded_forces=False))

openff/interchange/_tests/unit_tests/smirnoff/test_base.py

@@ -1,3 +1,5 @@
+import random
+
 import pytest
 from openff.toolkit.topology import Topology
 from openff.toolkit.typing.engines.smirnoff.parameters import (
@@ -6,7 +8,11 @@
 )
 
 from openff.interchange.exceptions import InvalidParameterHandlerError
-from openff.interchange.smirnoff import SMIRNOFFAngleCollection, SMIRNOFFCollection
+from openff.interchange.smirnoff import (
+    SMIRNOFFAngleCollection,
+    SMIRNOFFCollection,
+    SMIRNOFFElectrostaticsCollection,
+)
 
 
 class TestSMIRNOFFCollection:
@@ -49,3 +55,16 @@ def supported_parameters(cls):
                 parameter_handler=angle_Handler,
                 topology=Topology(),
             )
+
+
+def test_json_roundtrip_preserves_float_values():
+    """Reproduce issue #908."""
+    scale_factor = 0.5 + random.random() * 0.5
+
+    collection = SMIRNOFFElectrostaticsCollection(scale_14=scale_factor)
+
+    assert collection.scale_14 == scale_factor
+
+    roundtripped = SMIRNOFFElectrostaticsCollection.parse_raw(collection.json())
+
+    assert roundtripped.scale_14 == scale_factor

openff/interchange/smirnoff/_base.py

@@ -54,7 +54,11 @@ def collection_loader(data: str) -> dict:
     tmp: dict[str, Optional[Union[int, bool, str]]] = {}
 
     for key, val in json.loads(data).items():
-        if isinstance(val, (str, bool, type(None))):
+        if val is None:
+            tmp[key] = val
+        elif isinstance(val, (int, float, bool)):
+            tmp[key] = val
+        elif isinstance(val, (str)):
             # These are stored as string but must be parsed into `Quantity`
             if key in ("cutoff", "switch_width"):
                 tmp[key] = unit.Quantity(*json.loads(val).values())  # type: ignore[arg-type]