Allows buildASTSchema to throw errors with source locations.

src/error/syntaxError.js

@@ -11,6 +11,7 @@
 import { getLocation } from '../language/location';
 import type { Source } from '../language/source';
 import { GraphQLError } from './GraphQLError';
+import type { ASTNode } from '../language/ast';
 
 /**
  * Produces a GraphQLError representing a syntax error, containing useful
@@ -32,6 +33,26 @@ export function syntaxError(
   return error;
 }
 
+/**
+ * Produces a string for the invarant(...) function that renders the location
+ * where an error occurred. If no source is passed in, it renders the message
+ * without context.
+ */
+export function invariantError(
+  message: string,
+  node: ASTNode,
+  source: ?Source
+): string {
+  const position = node.loc ? node.loc.start : null;
+  if (position != null && source != null) {
+    const location = getLocation(source, position);
+    return `${message} (${location.line}:${location.column}) ` +
+      '\n\n' + highlightSourceAtLocation(source, location);
+  } else {
+    return message;
+  }
+}
+
 /**
  * Render a helpful description of the location of the error in the GraphQL
  * Source document.

src/utilities/buildASTSchema.js

@@ -13,9 +13,11 @@ import invariant from '../jsutils/invariant';
 import keyValMap from '../jsutils/keyValMap';
 import { valueFromAST } from './valueFromAST';
 import { TokenKind } from '../language/lexer';
+import { getLocation } from '../language/location';
 import { parse } from '../language/parser';
-import type { Source } from '../language/source';
+import { Source } from '../language/source';
 import { getArgumentValues } from '../execution/values';
+import { invariantError } from '../error/syntaxError';
 
 import {
   LIST_TYPE,
@@ -135,7 +137,7 @@ function getNamedTypeNode(typeNode: TypeNode): NamedTypeNode {
  * Given that AST it constructs a GraphQLSchema. The resulting schema
  * has no resolve methods, so execution will use default resolvers.
  */
-export function buildASTSchema(ast: DocumentNode): GraphQLSchema {
+export function buildASTSchema(ast: DocumentNode, source?: Source): GraphQLSchema {
   if (!ast || ast.kind !== DOCUMENT) {
     throw new Error('Must provide a document ast.');
   }
@@ -300,25 +302,29 @@ export function buildASTSchema(ast: DocumentNode): GraphQLSchema {
 
   function produceInputType(typeNode: TypeNode): GraphQLInputType {
     const type = produceType(typeNode);
-    invariant(isInputType(type), 'Expected Input type.');
+    invariant(isInputType(type),
+      invariantError('Expected Input type', typeNode, source));
     return (type: any);
   }
 
   function produceOutputType(typeNode: TypeNode): GraphQLOutputType {
     const type = produceType(typeNode);
-    invariant(isOutputType(type), 'Expected Output type.');
+    invariant(isOutputType(type),
+      invariantError('Expected Output type', typeNode, source));
     return (type: any);
   }
 
   function produceObjectType(typeNode: TypeNode): GraphQLObjectType {
     const type = produceType(typeNode);
-    invariant(type instanceof GraphQLObjectType, 'Expected Object type.');
+    invariant(type instanceof GraphQLObjectType,
+      invariantError('Expected Object type', typeNode, source));
     return type;
   }
 
   function produceInterfaceType(typeNode: TypeNode): GraphQLInterfaceType {
     const type = produceType(typeNode);
-    invariant(type instanceof GraphQLInterfaceType, 'Expected Interface type.');
+    invariant(type instanceof GraphQLInterfaceType,
+      invariantError('Expected Interface type', typeNode, source));
     return type;
   }
 
@@ -518,7 +524,8 @@ export function getDescription(node: { loc?: Location }): ?string {
  * document.
  */
 export function buildSchema(source: string | Source): GraphQLSchema {
-  return buildASTSchema(parse(source));
+  const sourceObj = typeof source === 'string' ? new Source(source) : source;
+  return buildASTSchema(parse(sourceObj), sourceObj);
 }
 
 // Count the number of spaces on the starting side of a string.