fix(composition): Enable and debug tests for post-merge validations (#8719)

Author: tninesling

apollo-federation/src/composition/satisfiability/satisfiability_error.rs

@@ -100,10 +100,7 @@ pub(super) fn shareable_field_non_intersecting_runtime_types_error(
         {}.\n\
         This is not allowed as shared fields must resolve the same way in all subgraphs, and that \
         implies at least some common runtime types between the subgraphs.",
-        operation,
-        field_definition_position,
-        field.ty.inner_named_type(),
-        type_strings,
+        operation, field_definition_position, field.ty, type_strings,
     );
     errors.push(CompositionError::ShareableHasMismatchedRuntimeTypes { message });
     Ok(())

apollo-federation/src/query_graph/graph_path/transition.rs

@@ -149,11 +149,15 @@ impl TransitionGraphPath {
                     let Selection::Field(field) = field else {
                         return None;
                     };
-                    if !field
+                    // Check if the field definition in the schema has @external
+                    // We need to look up the actual field definition because the parsed
+                    // field set doesn't include directives from the schema
+                    let field_def = field
                         .field
-                        .directives
-                        .has(external_directive_definition_name)
-                    {
+                        .field_position
+                        .get(subgraph_schema.schema())
+                        .ok()?;
+                    if !field_def.directives.has(external_directive_definition_name) {
                         return None;
                     }
                     Some(field.field.name().clone())

apollo-federation/tests/composition/mod.rs

@@ -28,6 +28,7 @@ pub(crate) mod test_helpers {
     use apollo_federation::composition::compose;
     use apollo_federation::error::CompositionError;
     use apollo_federation::error::FederationError;
+    use apollo_federation::subgraph::test_utils::remove_indentation;
     use apollo_federation::subgraph::typestate::Subgraph;
     use apollo_federation::supergraph::CompositionHint;
     use apollo_federation::supergraph::Satisfiable;
@@ -114,6 +115,9 @@ pub(crate) mod test_helpers {
         for (i, (expected_code, expected_message)) in expected_errors.iter().enumerate() {
             let (error_code, error_str) = &error_strings[i];
 
+            let error_str = remove_indentation(error_str);
+            let expected_message = remove_indentation(expected_message);
+
             // Check error code
             assert!(
                 error_code == expected_code,