fix: handle mutation failure (#230)

---------

Co-authored-by: Paul Le Bras <[email protected]>

Author: paullebras

lib/query-validation-visitor.js

@@ -98,7 +98,7 @@ module.exports = class QueryValidationVisitor {
     this.currentField = node
 
     // this if handles union type correctly
-    if (this.currentTypeInfo.typeDef.getFields) { this.currentrFieldDef = this.currentTypeInfo.typeDef.getFields()[node.name.value] }
+    if (this.currentTypeInfo?.typeDef?.getFields) { this.currentrFieldDef = this.currentTypeInfo.typeDef.getFields()[node.name.value] }
 
     if (this.currentrFieldDef) {
       const newTypeDef = getNamedType(this.currentrFieldDef.type)

test/mutation-failure.test.js

@@ -0,0 +1,46 @@
+const { strictEqual } = require('assert')
+
+module.exports.test = function (setup, implType) {
+  describe('GraphQL schema setup', function () {
+    before(async function () {
+      this.typeDefs = /* GraphQL */`
+        type Query {
+            book: Book
+        }
+        type Book {
+            title: String
+        }
+      `
+
+      this.request = await setup({ typeDefs: this.typeDefs })
+    })
+
+    describe('Mutation operation failure', function () {
+      it('should fail but not throw "Cannot read properties of undefined (reading \'getFields\')"', async function () {
+        const query = /* GraphQL */`
+          mutation GetBook {
+            book {
+                title
+            }
+          }
+        `
+
+        const { body, statusCode } = await this.request
+          .post('/graphql')
+          .set('Accept', 'application/json')
+          .send({ query })
+
+        strictEqual(
+          statusCode,
+          200,
+          'Expected HTTP status code 200 for successful GraphQL query execution.'
+        )
+        strictEqual(
+          body.errors[0].message,
+          'Schema is not configured to execute mutation operation.',
+          'Expected error message indicating failure in mutation operation.'
+        )
+      })
+    })
+  })
+}

test/testsuite-apollo-plugin.js

@@ -19,4 +19,5 @@ describe('Server validator based implementation - Apollo plugin', function () {
   require('./argument-dynamic.test').test(setup, IMPL_TYPE)
   require('./union.test').test(setup, IMPL_TYPE)
   require('./foreign-query-directives.test').test(setup, IMPL_TYPE)
+  require('./mutation-failure.test').test(setup, IMPL_TYPE)
 })