From be08d15c77df5f92c8d2903bdbc7e75e299a119e Mon Sep 17 00:00:00 2001
From: Steve Hollaar <steve.hollaar@gmail.com>
Date: Thu, 19 Apr 2018 12:06:22 -0700
Subject: [PATCH] RequiredFields rule supports inline fragments

---
 src/rules.js     | 18 +++++++++++++++---
 test/makeRule.js | 12 +++++++++++-
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/src/rules.js b/src/rules.js
index 88a65fe4..683b267f 100644
--- a/src/rules.js
+++ b/src/rules.js
@@ -12,6 +12,20 @@ export function OperationsMustHaveNames(context) {
   };
 }
 
+function getFieldWasRequestedOnNode(node, field, recursing = false) {
+  return node.selectionSet.selections.some(n => {
+    // If it's an inline fragment, we need to look deeper
+    if (n.kind === 'InlineFragment' && !recursing) {
+      return getFieldWasRequestedOnNode(n, field, true);
+    }
+    if (n.kind === 'FragmentSpread') {
+      // We don't know if the field was requested in this case, so default to not erroring.
+      return true;
+    }
+    return n.name.value === field;
+  });
+}
+
 export function RequiredFields(context, options) {
   return {
     Field(node) {
@@ -32,9 +46,7 @@ export function RequiredFields(context, options) {
           fieldAvaliableOnOfType = recursivelyCheckOnType(def.type.ofType, field);
         }
         if (fieldAvaliableOnType || fieldAvaliableOnOfType) {
-          const fieldWasRequested = !!node.selectionSet.selections.find(
-            n => (n.name.value === field || n.kind === 'FragmentSpread')
-          );
+          const fieldWasRequested = getFieldWasRequestedOnNode(node, field);
           if (!fieldWasRequested) {
             context.reportError(
               new GraphQLError(`'${field}' field required on '${node.name.value}'`, [node])
diff --git a/test/makeRule.js b/test/makeRule.js
index 94a431c5..c860c680 100644
--- a/test/makeRule.js
+++ b/test/makeRule.js
@@ -856,7 +856,8 @@ const requiredFieldsTestCases = {
   pass: [
     'const x = gql`query { allFilms { films { title } } }`',
     'const x = gql`query { stories { id comments { text } } }`',
-    'const x = gql`query { greetings { id, hello, foo } }`'
+    'const x = gql`query { greetings { id, hello, foo } }`',
+    'const x = gql`query { greetings { hello ... on Greetings { id } } }`',
   ],
   fail: [
     {
@@ -873,6 +874,15 @@ const requiredFieldsTestCases = {
         type: 'TaggedTemplateExpression',
       }],
     },
+    {
+      code: 'const x = gql`query { greetings { hello ... on Greetings { foo } } }`',
+      errors: [
+        {
+          message: `'id' field required on 'greetings'`,
+          type: 'TaggedTemplateExpression',
+        },
+      ],
+    },
   ],
 };