parser: add error handling for descriptions on shorthand queries and type extensions

Author: fotoetienne

src/language/__tests__/parser-test.ts

@@ -767,5 +767,18 @@ describe('Parser', () => {
         expect(varDef.type.name.value).to.equal('Int');
       }
     });
+
+    it('produces sensible error for description on shorthand query', () => {
+      expect(() =>
+        parse(dedent`
+          "This is a description"
+          {
+            field
+          }
+        `),
+      ).to.throw(
+        'Syntax Error: Unexpected description, descriptions are not supported on shorthand queries.',
+      );
+    });
   });
 });

src/language/parser.ts

@@ -270,12 +270,6 @@ export class Parser {
 
     if (keywordToken.kind === TokenKind.NAME) {
       switch (keywordToken.value) {
-        case 'query':
-        case 'mutation':
-        case 'subscription':
-          return this.parseOperationDefinition();
-        case 'fragment':
-          return this.parseFragmentDefinition();
         case 'schema':
           return this.parseSchemaDefinition();
         case 'scalar':
@@ -292,18 +286,37 @@ export class Parser {
           return this.parseInputObjectTypeDefinition();
         case 'directive':
           return this.parseDirectiveDefinition();
+      }
+
+      if (hasDescription && keywordToken.value === 'extend') {
+        throw syntaxError(
+          this._lexer.source,
+          this._lexer.token.start,
+          'Unexpected description, descriptions are not supported on type extensions.',
+        );
+      }
+
+      switch (keywordToken.value) {
+        case 'query':
+        case 'mutation':
+        case 'subscription':
+          return this.parseOperationDefinition();
+        case 'fragment':
+          return this.parseFragmentDefinition();
         case 'extend':
-          if (hasDescription) {
-            throw syntaxError(
-              this._lexer.source,
-              this._lexer.token.start,
-              'Unexpected description, descriptions are not supported on type extensions.',
-            );
-          }
           return this.parseTypeSystemExtension();
       }
     }
 
+    // Check for shorthand query with description
+    if (hasDescription && keywordToken.kind === TokenKind.BRACE_L) {
+      throw syntaxError(
+        this._lexer.source,
+        this._lexer.token.start,
+        'Unexpected description, descriptions are not supported on shorthand queries.',
+      );
+    }
+
     throw this.unexpected(keywordToken);
   }