Fix explicit proof version zero resolution

src/kontrol/foundry.py

@@ -962,7 +962,7 @@ def resolve_proof_version(
 
         method_status = method.up_to_date(self.digest_file)
 
-        if user_specified_version:
+        if user_specified_version is not None:
             _LOGGER.info(f'Using user-specified version {user_specified_version} for test {test}')
             if not Proof.proof_data_exists(f'{test}:{user_specified_version}', self.proofs_dir):
                 raise ValueError(f'The specified version {user_specified_version} of proof {test} does not exist.')

src/tests/unit/test_latest_proof_version.py

@@ -1,9 +1,13 @@
 from __future__ import annotations
 
+from pathlib import Path
+from types import SimpleNamespace
 from typing import TYPE_CHECKING
 
 import pytest
+from pyk.proof.proof import Proof
 
+import kontrol.foundry as foundry_module
 from kontrol.foundry import Foundry
 
 if TYPE_CHECKING:
@@ -63,3 +67,40 @@ def test_foundry_latest_proof_version(
 
     # Then
     assert latest_version == expected_version
+
+
+RESOLVE_PROOF_VERSION_DATA: list[tuple[str, int | None, int]] = [
+    ('explicit_zero', 0, 0),
+    ('explicit_nonzero', 2, 2),
+    ('omitted', None, 3),
+]
+
+
+@pytest.mark.parametrize(
+    'test_id,user_specified_version,expected_version',
+    RESOLVE_PROOF_VERSION_DATA,
+    ids=[test_id for test_id, *_ in RESOLVE_PROOF_VERSION_DATA],
+)
+def test_foundry_resolve_proof_version(
+    monkeypatch: MonkeyPatch, test_id: str, user_specified_version: int | None, expected_version: int
+) -> None:
+    # Given
+    test = 'long%path%to%test%DeeplyNestedTest.testWithMultipleVersions()'
+    method = SimpleNamespace(up_to_date=lambda _digest_file: True)
+
+    monkeypatch.setattr(Foundry, '__init__', lambda _: None)
+    monkeypatch.setattr(Foundry, 'digest_file', Path('digest'))
+    monkeypatch.setattr(Foundry, 'proofs_dir', Path('proofs'))
+    monkeypatch.setattr(Foundry, 'list_proof_dir', mock_listdir)
+    monkeypatch.setattr(Foundry, 'get_contract_and_method', lambda _self, _test: (None, method))
+    monkeypatch.setattr(foundry_module, 'kontrol_up_to_date', lambda _digest_file: True)
+
+    foundry = Foundry()  # type: ignore
+    existing_proofs = mock_listdir(foundry)
+    monkeypatch.setattr(Proof, 'proof_data_exists', lambda proof_id, _proofs_dir: proof_id in existing_proofs)
+
+    # When
+    version = foundry.resolve_proof_version(test, reinit=False, user_specified_version=user_specified_version)
+
+    # Then
+    assert version == expected_version