Report the default's literal as Violation.name for required-with-default

CHANGELOG.md

@@ -42,6 +42,12 @@ format changes.
     target's, and a oneof field.
   - **Error text** matches protowire-go's. Text a caller matched on changes.
 
+- **`Violation.name` for `(pxf.required)` with `(pxf.default)` on one field is
+  the default's literal** (#30, trendvidia/protowire-go#211). It was the bare
+  field name, which `element` already holds. An empty default gives an empty
+  `name`. This matches the other ports. For `(pxf.required)` on a oneof member,
+  `name` is the oneof's name, as protowire-cpp reports it.
+
 ### Added
 
 - **`Violation.kind` values `"default_option"`, `"retired_number"` and

src/_protowire/module.cc

@@ -253,7 +253,6 @@ PxfValidateDescriptor(nb::bytes fds_bytes, const std::string& full_name) {
       case protowire::pxf::ViolationKind::kKeyOption: kind = "key_option"; break;
       case protowire::pxf::ViolationKind::kRequiredOption:
         kind = "required_default";
-        name = v.element.substr(v.element.rfind('.') + 1);  // cpp leaves name empty here.
         break;
       case protowire::pxf::ViolationKind::kDefaultOption:  kind = "default_option";   break;
       case protowire::pxf::ViolationKind::kRetiredNumber:  kind = "retired_number";   break;

src/protowire/pxf.py

@@ -125,9 +125,10 @@ class Violation:
         "well_known_shape",
     ]
     element: str  # fully-qualified protobuf name, e.g. "trades.v1.Side.null"
-    # The reserved identifier, the (pxf.key) value, the field's name
-    # ("required_default"), the (pxf.default) literal ("default_option"), or
-    # the retired number ("retired_number"); empty for "well_known_shape".
+    # The reserved identifier, the (pxf.key) value, the (pxf.default) literal
+    # ("default_option", and "required_default" beside a default), the oneof's
+    # name ("required_default" on a oneof member), or the retired number
+    # ("retired_number"); empty for "well_known_shape".
     name: str
     file: str  # .proto file path the element is declared in
 

tests/test_pxf_required_default.py

@@ -74,7 +74,7 @@ def _one_field(options: bytes):
     return _bind(fd)
 
 
-def _assert_refused(fds: bytes, cls, element: str, file: str) -> None:
+def _assert_refused(fds: bytes, cls, element: str, file: str, name: str = "x") -> None:
     # A document supplying the field: the schema is wrong whatever the input.
     doc = 'f = "y"\n' if cls.DESCRIPTOR.fields_by_name.get("f") else ""
     for call in (
@@ -91,7 +91,7 @@ def _assert_refused(fds: bytes, cls, element: str, file: str) -> None:
         pxf.Violation(
             kind="required_default",
             element=element,
-            name=element.rsplit(".", 1)[1],
+            name=name,  # The (pxf.default) literal (protowire-go#211).
             file=file,
         )
     ]
@@ -102,6 +102,11 @@ def test_required_with_default_is_refused_at_bind():
     _assert_refused(fds, cls, "t.M.f", "one.proto")
 
 
+def test_empty_default_gives_an_empty_name():
+    fds, cls = _one_field(REQUIRED + _opt_str(_DEFAULT, ""))
+    _assert_refused(fds, cls, "t.M.f", "one.proto", name="")
+
+
 def test_option_order_does_not_matter():
     fds, cls = _one_field(DEFAULT + REQUIRED)
     _assert_refused(fds, cls, "t.M.f", "one.proto")
@@ -151,3 +156,19 @@ def test_misplaced_key_option_is_reported_with_its_kind():
     _add_field(fd.message_type.add(name="M"), "f", 1, _opt_str(_KEY, "id"))
     _, cls = _bind(fd)
     assert [v.kind for v in pxf.validate_descriptor(cls())] == ["key_option"]
+
+
+def test_required_on_a_oneof_member_names_the_oneof():
+    # protowire-cpp v2.0.0 reports this under the same kind, with the oneof's
+    # name in `name` ("Oneof Members").
+    fd = _file("oneof.proto")
+    m = fd.message_type.add(name="M")
+    m.oneof_decl.add(name="pick")
+    _add_field(m, "a", 1, REQUIRED)
+    _add_field(m, "b", 2)
+    for f in m.field:
+        f.oneof_index = 0
+    _, cls = _bind(fd)
+    assert pxf.validate_descriptor(cls()) == [
+        pxf.Violation(kind="required_default", element="t.M.a", name="pick", file="oneof.proto")
+    ]