Add decision_engine/tests/test_core.py

decision_engine/tests/test_core.py

@@ -0,0 +1,82 @@
+import pytest
+import types
+
+import decision_engine.core as core
+
+def make_run(**overrides):
+    base = {
+        'run_id': 'r1',
+        'pinned': False,
+        'warn_rate': 0.02,
+        'unknown_rate': 0.01,
+        'unknown_class': 'none',
+        'prev_label': 'PASS'
+    }
+    base.update(overrides)
+    return base
+
+
+def validate_result(result):
+    assert isinstance(result, dict)
+    assert 'final_decision' in result and 'reason' in result
+    assert result['final_decision'] in {'PASS', 'WARN', 'FAIL'}
+    assert isinstance(result['reason'], str)
+
+
+def test_pass_case():
+    run = make_run(warn_rate=0.01, unknown_rate=0.0)
+    result = core.evaluate_run(run)
+    validate_result(result)
+    assert result['final_decision'] == 'PASS'
+
+
+def test_warn_case_high_warn_rate():
+    run = make_run(warn_rate=0.12, unknown_rate=0.02)
+    result = core.evaluate_run(run)
+    validate_result(result)
+    assert result['final_decision'] in {'WARN', 'FAIL'}
+
+
+def test_fail_case_unknown_rate():
+    run = make_run(warn_rate=0.01, unknown_rate=0.5)
+    result = core.evaluate_run(run)
+    validate_result(result)
+    assert result['final_decision'] == 'FAIL'
+
+
+def test_unknown_class_affects_decision():
+    run = make_run(unknown_class='schema_violation', unknown_rate=0.05)
+    result = core.evaluate_run(run)
+    validate_result(result)
+    assert 'schema_violation' in result['reason'].lower()
+
+
+def test_pinned_runs_handling():
+    run = make_run(pinned=True, warn_rate=0.2)
+    result = core.evaluate_run(run)
+    validate_result(result)
+    # pinned might downgrade fail to warn or pass depending on policy
+    assert result['final_decision'] in {'PASS', 'WARN', 'FAIL'}
+
+
+def test_missing_field_type_validation():
+    # Invalid type or missing field should raise TypeError or ValueError
+    with pytest.raises((TypeError, ValueError, KeyError)):
+        bad_run = {'run_id': 'x', 'warn_rate': 'not_num'}
+        core.evaluate_run(bad_run)
+
+
+def test_prev_label_consistency(monkeypatch):
+    run = make_run(prev_label='FAIL', warn_rate=0.02)
+    result = core.evaluate_run(run)
+    validate_result(result)
+    assert isinstance(result['reason'], str)
+
+
+def test_reason_field_contains_rationale():
+    run = make_run(warn_rate=0.15, unknown_rate=0.1)
+    result = core.evaluate_run(run)
+    validate_result(result)
+    # Should give human-readable rationale
+    msg = result['reason'].lower()
+    assert any(keyword in msg for keyword in ('warn', 'fail', 'unknown', 'threshold'))