fix(lsp): surface unused fragment definition leaves (#299)

.changeset/wise-coins-look.md

@@ -0,0 +1,5 @@
+---
+'@0no-co/graphqlsp': patch
+---
+
+Correctly identify unused fields on a fragment-definition, these have no parent to group by so we display them as unused leaves

packages/example-tada/src/Pokemon.tsx

@@ -3,6 +3,7 @@ import { FragmentOf, graphql, readFragment } from './graphql';
 export const Fields = { Pokemon: graphql(`
   fragment Pok on Pokemon {
     resistant
+    types
   }`)
 }
 

packages/graphqlsp/src/fieldUsage.ts

@@ -495,18 +495,22 @@ export const checkFieldUsageInFile = (
       const unused = allPaths.filter(x => !allAccess.includes(x));
       const aggregatedUnusedFields = new Set<string>();
       const unusedChildren: { [key: string]: Set<string> } = {};
+      const unusedFragmentLeaf = new Set<string>();
       unused.forEach(unusedField => {
         const split = unusedField.split('.');
         split.pop();
         const parentField = split.join('.');
         const loc = fieldToLoc.get(parentField);
-        if (!loc) return;
 
-        aggregatedUnusedFields.add(parentField);
-        if (unusedChildren[parentField]) {
-          unusedChildren[parentField].add(unusedField);
+        if (loc) {
+          aggregatedUnusedFields.add(parentField);
+          if (unusedChildren[parentField]) {
+            unusedChildren[parentField].add(unusedField);
+          } else {
+            unusedChildren[parentField] = new Set([unusedField]);
+          }
         } else {
-          unusedChildren[parentField] = new Set([unusedField]);
+          unusedFragmentLeaf.add(unusedField);
         }
       });
 
@@ -524,6 +528,18 @@ export const checkFieldUsageInFile = (
             .join(', ')} are not used.`,
         });
       });
+
+      unusedFragmentLeaf.forEach(field => {
+        const loc = fieldToLoc.get(field)!;
+        diagnostics.push({
+          file: source,
+          length: loc.length,
+          start: node.getStart() + loc.start + 1,
+          category: ts.DiagnosticCategory.Warning,
+          code: UNUSED_FIELD_CODE,
+          messageText: `Field ${field} is not used.`,
+        });
+      });
     });
   } catch (e: any) {
     console.error('[GraphQLSP]: ', e.message, e.stack);