feat(federation): started query plan correctness checker

- implemented ResponseShape computation from an operation

apollo-federation/cli/src/main.rs

@@ -248,10 +248,13 @@ fn cmd_plan(
 
     let query_doc =
         ExecutableDocument::parse_and_validate(planner.api_schema().schema(), query, query_path)?;
-    print!(
-        "{}",
-        planner.build_query_plan(&query_doc, None, Default::default())?
-    );
+    let query_plan = planner.build_query_plan(&query_doc, None, Default::default())?;
+    println!("{query_plan}");
+    apollo_federation::query_plan::correctness::check_plan(
+        planner.api_schema(),
+        &query_doc,
+        &query_plan,
+    )?;
     Ok(())
 }
 

apollo-federation/src/query_plan/correctness/mod.rs

@@ -0,0 +1,23 @@
+pub mod response_shape;
+#[cfg(test)]
+pub mod response_shape_test;
+
+use apollo_compiler::validation::Valid;
+use apollo_compiler::ExecutableDocument;
+
+use crate::query_plan::QueryPlan;
+use crate::schema::ValidFederationSchema;
+use crate::FederationError;
+
+//==================================================================================================
+// check_plan
+
+pub fn check_plan(
+    schema: &ValidFederationSchema,
+    operation_doc: &Valid<ExecutableDocument>,
+    _plan: &QueryPlan,
+) -> Result<(), FederationError> {
+    let rs = response_shape::compute_response_shape(operation_doc, schema)?;
+    println!("\nResponse shape from operation:\n{rs}");
+    Ok(())
+}