schema-reporting: Check whether overrideReportedSchema is parsable/valid

CHANGELOG.md

@@ -11,7 +11,7 @@ The version headers in this history reflect the versions of Apollo Server itself
 
 ## v2.18.0
 
-- _Nothing yet! Stay tuned!_
+- `apollo-engine-reporting`: Parse and validate any schema passed via `overrideReportedSchema`, and throw accordingly on unparsable or invalid schemas.
 
 ## v2.17.0
 

packages/apollo-engine-reporting/src/agent.ts

@@ -1,10 +1,12 @@
 import os from 'os';
 import { gzip } from 'zlib';
 import {
+  buildSchema,
   DocumentNode,
   GraphQLError,
   GraphQLSchema,
   printSchema,
+  validateSchema
 } from 'graphql';
 import {
   ReportHeader,
@@ -510,6 +512,26 @@ export class EngineReportingAgent<TContext = any> {
       }
     }
 
+    // Ensure a provided override schema can be parsed and validated
+    if (options.overrideReportedSchema) {
+      try {
+        const validationErrors = validateSchema(
+          buildSchema(options.overrideReportedSchema, { noLocation: true })
+        );
+        if (validationErrors.length) {
+          throw new Error(
+            validationErrors.map((error) => error.message)
+              .join('\n')
+          );
+        }
+      } catch (err) {
+        throw new Error(
+          "The schema provided to overrideReportedSchema failed to parse or" +
+          `validate: ${err.message}`
+        )
+      }
+    }
+
     if (options.reportSchema !== undefined) {
       this.schemaReport = options.reportSchema;
     } else {