test: two-pass import validation so binding order cannot matter

pytest raises aliases are collected across the whole file FIRST, then
every competing import (wherever it appears, even before the genuine
binding) is rejected - closing the reversed-order spoof

tests/test_dao_children.py

@@ -666,38 +666,41 @@ def test_dao_matrix_test_file_raw_probes_are_only_constraint_probes() -> None:
             NotIntegrityError and fake.IntegrityError fail).
             """
             # Names bound to pytest's raises: parse the FILE's actual
-            # Import nodes.  A bare Name('raises') is trusted only when
-            # an alias binds it from the pytest module; ANY other import
-            # (Import or ImportFrom) binding 'raises', 'pytest', or any
-            # raises alias from a non-pytest module fails closed, so a
-            # spoofed module or shadowed alias cannot defeat the check.
-            raises_bindings: set[str] = set()
+            # Import nodes in TWO passes so order cannot matter — pass
+            # one collects every binding pytest's raises gets (whatever
+            # alias), pass two rejects ANY competing binding of those
+            # names (or of 'pytest' itself) from a non-pytest import,
+            # wherever it appears.  A spoof imported BEFORE the genuine
+            # binding therefore still fails.
+            pytest_raises_aliases: set[str] = set()
+            for file_node in ast.walk(tree):
+                if (
+                    isinstance(file_node, ast.ImportFrom)
+                    and file_node.module == "pytest"
+                ):
+                    for alias in file_node.names:
+                        if alias.name == "raises":
+                            pytest_raises_aliases.add(
+                                alias.asname or alias.name
+                            )
+            raises_bindings: set[str] = set(pytest_raises_aliases)
             for file_node in ast.walk(tree):
                 if isinstance(file_node, ast.ImportFrom):
                     if file_node.module == "pytest":
-                        for alias in file_node.names:
-                            if alias.name == "raises":
-                                raises_bindings.add(
-                                    alias.asname or alias.name
-                                )
-                    # Any ImportFrom binding the guarded names from a
-                    # non-pytest module fails closed.
+                        continue
                     for alias in file_node.names:
                         bound = alias.asname or alias.name
-                        if (
-                            bound in raises_bindings | {"pytest"}
-                            and file_node.module != "pytest"
-                        ):
+                        if bound in raises_bindings | {"pytest"}:
                             raise AssertionError(
                                 f"shadowed import of {bound!r} from "
                                 f"{file_node.module!r} defeats the "
                                 "pytest.raises probe validation"
                             )
                 elif isinstance(file_node, ast.Import):
-                    # import fake_module as pytest (or as anything the
-                    # raises machinery trusts) fails closed.  A plain
-                    # `import pytest` (alias.name == 'pytest', no asname)
-                    # is the genuine module binding and is allowed.
+                    # import fake_module as pytest (or as any raises
+                    # alias) fails closed.  A plain `import pytest`
+                    # (alias.name == 'pytest', no asname) is the genuine
+                    # module binding and is allowed.
                     for alias in file_node.names:
                         bound = alias.asname or alias.name
                         genuine_pytest = (