Add clear error message when connect link version is wrong (#6740)

apollo-federation/src/sources/connect/spec/mod.rs

@@ -30,6 +30,7 @@ pub(crate) use directives::extract_connect_directive_arguments;
 pub(crate) use directives::extract_source_directive_arguments;
 pub(crate) use schema::ConnectHTTPArguments;
 pub(crate) use schema::SourceHTTPArguments;
+use strum_macros::EnumIter;
 
 use self::schema::CONNECT_DIRECTIVE_NAME_IN_SPEC;
 use self::schema::SOURCE_DIRECTIVE_NAME_IN_SPEC;
@@ -43,13 +44,13 @@ use crate::link::Link;
 use crate::schema::FederationSchema;
 
 /// The known versions of the connect spec
-#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
+#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq, EnumIter)]
 pub enum ConnectSpec {
     V0_1,
 }
 
 impl ConnectSpec {
-    pub const fn as_str(&self) -> &'static str {
+    pub const fn as_str(self) -> &'static str {
         match self {
             Self::V0_1 => "0.1",
         }

apollo-federation/src/sources/connect/validation/mod.rs

@@ -50,6 +50,7 @@ use entity::EntityKeyChecker;
 use extended_type::validate_extended_type;
 use itertools::Itertools;
 use source_name::SourceName;
+use strum::IntoEnumIterator;
 use strum_macros::Display;
 use strum_macros::IntoStaticStr;
 use url::Url;
@@ -110,6 +111,32 @@ pub fn validate(source_text: &str, file_name: &str) -> ValidationResult {
         };
     };
 
+    if let Err(err) = ConnectSpec::try_from(&link.url.version) {
+        let available_versions = ConnectSpec::iter().map(ConnectSpec::as_str).collect_vec();
+        let message = if available_versions.len() == 1 {
+            // TODO: No need to branch here once multiple spec versions are available
+            format!("{err}; should be {version}.", version = ConnectSpec::V0_1)
+        } else {
+            // This won't happen today, but it's prepping for 0.2 so we don't forget
+            format!(
+                "{err}; should be one of {available_versions}.",
+                available_versions = available_versions.join(", "),
+            )
+        };
+        return ValidationResult {
+            errors: vec![Message {
+                code: Code::UnknownConnectorsVersion,
+                message,
+                locations: link_directive
+                    .line_column_range(&schema.sources)
+                    .into_iter()
+                    .collect(),
+            }],
+            has_connectors: true,
+            schema,
+        };
+    }
+
     let federation = Link::for_identity(&schema, &Identity::federation_identity());
     let external_directive_name = federation
         .map(|(link, _)| link.directive_name_in_schema(&EXTERNAL_DIRECTIVE_NAME))
@@ -609,6 +636,8 @@ pub enum Code {
     UnsupportedVariableType,
     /// A variable is nullable in a location which requires non-null at runtime
     NullabilityMismatch,
+    /// The version set in the connectors `@link` URL is not recognized
+    UnknownConnectorsVersion,
 }
 
 impl Code {

apollo-federation/src/sources/connect/validation/snapshots/validation_tests@connect_spec_version_error.graphql.snap

@@ -0,0 +1,14 @@
+---
+source: apollo-federation/src/sources/connect/validation/mod.rs
+expression: "format!(\"{:#?}\", result.errors)"
+input_file: apollo-federation/src/sources/connect/validation/test_data/connect_spec_version_error.graphql
+---
+[
+    Message {
+        code: UnknownConnectorsVersion,
+        message: "Unknown connect version: 0.2; should be 0.1.",
+        locations: [
+            2:3..5:4,
+        ],
+    },
+]

apollo-federation/src/sources/connect/validation/test_data/connect_spec_version_error.graphql

@@ -0,0 +1,6 @@
+extend schema
+  @link(
+    url: "https://specs.apollo.dev/connect/v0.2"
+    import: ["@connect", "@source"]
+  )
+