sched: extract shared input traversal behind SourceResolver seam (T03)

tests/core/test_input_sources.py

@@ -0,0 +1,108 @@
+"""Source-resolver seam: one traversal, distinct graph/schedule models (T03)."""
+
+from __future__ import annotations
+
+import pytest
+
+from wf_core.errors import WorkflowExecutionError
+from wf_core.models.input_bindings import (
+    ObjectExpression,
+    PathExpression,
+    validate_input_expression_limits,
+)
+from wf_core.runtime.input_bindings import (
+    resolve_input_expression,
+    resolve_input_expression_with_resolver,
+)
+from wf_core.runtime.input_sources import (
+    GraphSourceResolver,
+    MappingSourceResolver,
+    resolve_composed_expression,
+    walk_expression_paths,
+)
+
+
+def test_graph_resolver_matches_legacy_resolution() -> None:
+    expr = ObjectExpression.model_validate(
+        {
+            "kind": "object",
+            "fields": {
+                "team": {"kind": "literal", "value": "eng"},
+                "tags": {"kind": "array", "items": [{"kind": "literal", "value": "a"}]},
+                "req": {"kind": "path", "path": "input.request_id"},
+            },
+        }
+    )
+    kwargs = {
+        "state": {},
+        "workflow_input": {"request_id": "r1"},
+        "context": {},
+        "label": "probe",
+        "location": "$",
+    }
+    assert resolve_input_expression(expr, **kwargs) == {
+        "team": "eng",
+        "tags": ["a"],
+        "req": "r1",
+    }
+    resolver = GraphSourceResolver(
+        state={}, workflow_input={"request_id": "r1"}, context={}
+    )
+    assert resolve_composed_expression(
+        expr, resolver=resolver, label="probe", location="$"
+    ) == {"team": "eng", "tags": ["a"], "req": "r1"}
+    assert resolve_input_expression_with_resolver(
+        expr, resolver=resolver, label="probe", location="$"
+    ) == {"team": "eng", "tags": ["a"], "req": "r1"}
+
+
+def test_graph_resolver_does_not_smuggle_occurrence_values() -> None:
+    # Occurrence values must not be faked through graph context: a path that
+    # looks like an occurrence root is rejected by GraphSourcePath itself,
+    # and a resolver carrying occurrence data under context is a contract
+    # violation, not a supported seam.
+    from wf_core.paths import GraphSourcePath
+
+    with pytest.raises(ValueError):
+        GraphSourcePath.parse("occurrence.scheduled_at")
+    resolver = GraphSourceResolver(state={}, workflow_input={}, context={})
+    expr = PathExpression.model_validate({"kind": "path", "path": "input.missing"})
+    with pytest.raises(WorkflowExecutionError):
+        resolve_composed_expression(expr, resolver=resolver, label="t", location="$")
+
+
+def test_mapping_resolver_is_distinct_from_graph_resolver() -> None:
+    occ = MappingSourceResolver(
+        {"schedule_id": "s", "scheduled_at": "2026-09-08T13:00:00+00:00"}
+    )
+    assert occ.resolve_field("schedule_id") == "s"
+    with pytest.raises(WorkflowExecutionError, match="unknown occurrence field"):
+        occ.resolve_field("nope")
+    assert not hasattr(occ, "resolve_path")
+
+
+def test_walk_order_matches_validation_suffixes() -> None:
+    expr = ObjectExpression.model_validate(
+        {
+            "kind": "object",
+            "fields": {
+                "a": {"kind": "path", "path": "input.x"},
+                "b": {
+                    "kind": "array",
+                    "items": [{"kind": "path", "path": "state.y"}],
+                },
+            },
+        }
+    )
+    assert [suffix for _, suffix in walk_expression_paths(expr)] == [
+        "fields.a.path",
+        "fields.b.items[0].path",
+    ]
+
+
+def test_budget_validator_is_shared_entry_point() -> None:
+    deep: dict = {"kind": "literal", "value": 0}
+    for _ in range(70):
+        deep = {"kind": "array", "items": [deep]}
+    with pytest.raises(ValueError, match="limit exceeded"):
+        validate_input_expression_limits(deep)