fix + add tests

core/dbt/context/providers.py

@@ -481,6 +481,7 @@ def resolve(
         target_version: Optional[NodeVersion] = None,
     ) -> RelationProxy:
         target_model = self.manifest.resolve_ref(
+            self.model,
             target_name,
             target_package,
             target_version,

core/dbt/exceptions.py

@@ -1971,7 +1971,7 @@ def __init__(self, duped_name, unique_ids, node=None):
     def get_message(self) -> str:
         msg = (
             f'dbt found multiple potential nodes when referencing "{self.duped_name}" - {self.unique_ids}.'
-            f"\nTo fix this, specify which package to use in 'ref' (one of: {self.packages})."
+            f"\nTo fix this, specify which package to use as the first argument to 'ref' (one of: {self.packages})."
         )
         return msg
 

test/unit/test_manifest.py

@@ -37,6 +37,7 @@
 )
 
 from dbt.events.functions import reset_metadata_vars
+from dbt.exceptions import AmbiguousResourceNameRefError
 from dbt.flags import set_from_args
 
 from dbt.node_types import NodeType
@@ -1443,6 +1444,36 @@ def _refable_parameter_sets():
                 version=None,
                 expected=None,
             ),
+            # duplicate node name across package
+            FindNodeSpec(
+                nodes=[MockNode("project_a", "my_model"), MockNode("project_b", "my_model")],
+                sources=[],
+                package="project_a",
+                version=None,
+                expected=("project_a", "my_model"),
+            ),
+            # duplicate node name across package: root node preferred to package node
+            FindNodeSpec(
+                nodes=[MockNode("root", "my_model"), MockNode("project_a", "my_model")],
+                sources=[],
+                package=None,
+                version=None,
+                expected=("root", "my_model"),
+            ),
+            FindNodeSpec(
+                nodes=[MockNode("root", "my_model"), MockNode("project_a", "my_model")],
+                sources=[],
+                package="root",
+                version=None,
+                expected=("root", "my_model"),
+            ),
+            FindNodeSpec(
+                nodes=[MockNode("root", "my_model"), MockNode("project_a", "my_model")],
+                sources=[],
+                package="project_a",
+                version=None,
+                expected=("project_a", "my_model"),
+            ),
         ]
     )
     return sets
@@ -1486,6 +1517,21 @@ def test_resolve_ref(nodes, sources, package, version, expected):
         assert result.package_name == expected_package
 
 
+def test_resolve_ref_ambiguous_resource_name_across_packages():
+    manifest = make_manifest(
+        nodes=[MockNode("project_a", "my_model"), MockNode("project_b", "my_model")]
+    )
+    with pytest.raises(AmbiguousResourceNameRefError):
+        manifest.resolve_ref(
+            source_node=None,
+            target_model_name="my_model",
+            target_model_package=None,
+            target_model_version=None,
+            current_project="root",
+            node_package="root",
+        )
+
+
 def _source_parameter_sets():
     sets = [
         # empties

tests/functional/duplicates/test_duplicate_model.py

@@ -1,6 +1,6 @@
 import pytest
 
-from dbt.exceptions import CompilationError, DuplicateResourceNameError
+from dbt.exceptions import CompilationError, AmbiguousAliasError
 from dbt.tests.fixtures.project import write_project_files
 from dbt.tests.util import run_dbt, get_manifest
 
@@ -88,7 +88,7 @@ def test_duplicate_model_disabled_partial_parsing(self, project):
         assert len(results) == 1
 
 
-class TestDuplicateModelEnabledAcrossPackages:
+class TestDuplicateModelAliasEnabledAcrossPackages:
     @pytest.fixture(scope="class")
     def models(self):
         return {"table_model.sql": enabled_model_sql}
@@ -105,10 +105,10 @@ def setUp(self, project_root):
     def packages(self):
         return {"packages": [{"local": "local_dependency"}]}
 
-    def test_duplicate_model_enabled_across_packages(self, project):
+    def test_duplicate_model_alias_enabled_across_packages(self, project):
         run_dbt(["deps"])
-        message = "dbt found two models with the name"
-        with pytest.raises(DuplicateResourceNameError) as exc:
+        message = "dbt found two resources with the database representation"
+        with pytest.raises(AmbiguousAliasError) as exc:
             run_dbt(["run"])
         assert message in str(exc.value)