fix(gatsby): Protect about possibly missing context in graphql

packages/gatsby/src/query/graphql-span-tracer.ts

@@ -5,6 +5,7 @@ import { IActivityArgs } from "gatsby-cli/src/reporter/reporter"
 import { IPhantomReporter } from "gatsby-cli/src/reporter/reporter-phantom"
 
 import { IGraphQLSpanTracer } from "../schema/type-definitions"
+import { pathToArray } from "./utils"
 
 /**
  * Tracks and knows how to get a parent span for a particular
@@ -72,13 +73,3 @@ export default class GraphQLSpanTracer implements IGraphQLSpanTracer {
     this.activities.set(path.join(`.`), activity)
   }
 }
-
-function pathToArray(path: Path | undefined): Array<string | number> {
-  const flattened: Array<string | number> = []
-  let curr: Path | undefined = path
-  while (curr) {
-    flattened.push(curr.key)
-    curr = curr.prev
-  }
-  return flattened.reverse()
-}

packages/gatsby/src/query/utils.ts

@@ -1,3 +1,5 @@
+import { Path } from "graphql/jsutils/Path"
+
 export const indentString = (string: string): string =>
   string.replace(/\n/g, `\n  `)
 
@@ -8,3 +10,13 @@ export const formatErrorDetails = (errorDetails: Map<string, any>): string =>
   ${indentString(details.toString())}`
     )
     .join(`\n`)
+
+export function pathToArray(path: Path | undefined): Array<string | number> {
+  const flattened: Array<string | number> = []
+  let curr: Path | undefined = path
+  while (curr) {
+    flattened.push(curr.key)
+    curr = curr.prev
+  }
+  return flattened.reverse()
+}

packages/gatsby/src/schema/infer/__tests__/merge-types.js

@@ -2,7 +2,7 @@ const { buildObjectType } = require(`../../types/type-builders`)
 const { store } = require(`../../../redux`)
 const { build } = require(`../..`)
 const { actions } = require(`../../../redux/actions`)
-const { defaultTracingResolver } = require(`../../resolvers`)
+const { defaultResolver } = require(`../../resolvers`)
 
 jest.mock(`gatsby-cli/lib/reporter`, () => {
   return {
@@ -286,7 +286,7 @@ describe(`merges explicit and inferred type definitions`, () => {
         expect(nestedNestedFields.conflict.type.toString()).toBe(`String!`)
 
         // Date resolvers
-        expect(fields.explicitDate.resolve).toBe(defaultTracingResolver)
+        expect(fields.explicitDate.resolve).toBe(defaultResolver)
         expect(fields.inferDate.resolve).toBeDefined()
       })
 
@@ -337,7 +337,7 @@ describe(`merges explicit and inferred type definitions`, () => {
         expect(nestedNestedFields.conflict.type.toString()).toBe(`String!`)
 
         // Date resolvers
-        expect(fields.explicitDate.resolve).toBe(defaultTracingResolver)
+        expect(fields.explicitDate.resolve).toBe(defaultResolver)
       })
 
       it(`with "infer(noDefaultResolvers: false)"`, async () => {
@@ -438,7 +438,7 @@ describe(`merges explicit and inferred type definitions`, () => {
         expect(nestedNestedFields.conflict.type.toString()).toBe(`String!`)
 
         // Date resolvers
-        expect(fields.explicitDate.resolve).toBe(defaultTracingResolver)
+        expect(fields.explicitDate.resolve).toBe(defaultResolver)
         expect(fields.inferDate.resolve).toBeDefined()
       })
 
@@ -543,7 +543,7 @@ describe(`merges explicit and inferred type definitions`, () => {
         expect(nestedNestedFields.conflict.type.toString()).toBe(`String!`)
 
         // Date resolvers
-        expect(fields.explicitDate.resolve).toBe(defaultTracingResolver)
+        expect(fields.explicitDate.resolve).toBe(defaultResolver)
       })
     })
   })
@@ -698,7 +698,7 @@ describe(`merges explicit and inferred type definitions`, () => {
     const { link, links } = schema.getType(`LinkTest`).getFields()
     expect(link.type.toString()).toBe(`Test!`)
     expect(links.type.toString()).toBe(`[Test!]!`)
-    expect(link.resolve).toBe(defaultTracingResolver)
-    expect(links.resolve).toBe(defaultTracingResolver)
+    expect(link.resolve).toBe(defaultResolver)
+    expect(links.resolve).toBe(defaultResolver)
   })
 })

packages/gatsby/src/schema/resolvers.ts

@@ -16,6 +16,9 @@ import {
   SelectionNode,
   FieldNode,
 } from "graphql"
+import { Path } from "graphql/jsutils/Path"
+const reporter = require(`gatsby-cli/lib/reporter`)
+import { pathToArray } from "../query/utils"
 import { getValueAt } from "../utils/get-value-at"
 import {
   GatsbyResolver,
@@ -472,7 +475,19 @@ export const defaultFieldResolver: GatsbyResolver<
   return null
 }
 
-export function tracingResolver<TSource, TArgs>(
+let WARNED_ABOUT_RESOLVERS = false
+function badResolverInvocationMessage(missingVar: string, path?: Path): string {
+  const resolverName = path ? `${pathToArray(path)} ` : ``
+  return `GraphQL Resolver ${resolverName}got called without "${missingVar}" argument. This might cause unexpected errors.
+
+It's likely that this has happened in a schemaCustomization with manually invoked resolver. If manually invoking resolvers, it's best to invoke them as follows:
+
+  resolve(parent, args, context, info)
+
+`
+}
+
+export function wrappingResolver<TSource, TArgs>(
   resolver: GatsbyResolver<TSource, TArgs>
 ): GatsbyResolver<TSource, TArgs> {
   return async function wrappedTracingResolver(
@@ -481,8 +496,18 @@ export function tracingResolver<TSource, TArgs>(
     context,
     info
   ): Promise<any> {
+    if (!WARNED_ABOUT_RESOLVERS) {
+      if (!info) {
+        reporter.warn(badResolverInvocationMessage(`info`))
+        WARNED_ABOUT_RESOLVERS = true
+      } else if (!context) {
+        reporter.warn(badResolverInvocationMessage(`context`, info.path))
+        WARNED_ABOUT_RESOLVERS = true
+      }
+    }
+
     let activity
-    if (context.tracer) {
+    if (context?.tracer) {
       activity = context.tracer.createResolverActivity(
         info.path,
         `${info.parentType.name}.${info.fieldName}`
@@ -499,4 +524,4 @@ export function tracingResolver<TSource, TArgs>(
   }
 }
 
-export const defaultTracingResolver = tracingResolver(defaultFieldResolver)
+export const defaultResolver = wrappingResolver(defaultFieldResolver)

packages/gatsby/src/schema/schema.js

@@ -26,8 +26,8 @@ const { addInferredType, addInferredTypes } = require(`./infer`)
 const {
   findOne,
   findManyPaginated,
-  tracingResolver,
-  defaultTracingResolver,
+  wrappingResolver,
+  defaultResolver,
 } = require(`./resolvers`)
 const {
   processFieldExtensions,
@@ -856,8 +856,8 @@ function attachTracingResolver({ schemaComposer }) {
         const field = typeComposer.getField(fieldName)
         typeComposer.extendField(fieldName, {
           resolve: field.resolve
-            ? tracingResolver(field.resolve)
-            : defaultTracingResolver,
+            ? wrappingResolver(field.resolve)
+            : defaultResolver,
         })
       })
     }

packages/gatsby/src/schema/types/__tests__/date.js

@@ -2,7 +2,7 @@ const { store } = require(`../../../redux`)
 const { actions } = require(`../../../redux/actions`)
 const { build } = require(`../..`)
 const withResolverContext = require(`../../context`)
-const { defaultTracingResolver } = require(`../../resolvers`)
+const { defaultResolver } = require(`../../resolvers`)
 const { isDate, looksLikeADate } = require(`../date`)
 
 jest.mock(`gatsby-cli/lib/reporter`, () => {
@@ -353,22 +353,22 @@ describe(`dateResolver`, () => {
     expect(fields.validNanosecond1.resolve).toBeDefined()
     expect(fields.validNanosecond2.resolve).toBeDefined()
     // expect(fields.invalidHighPrecision.resolve).toBeDefined()
-    expect(fields.invalidDate1.resolve).toBe(defaultTracingResolver)
-    expect(fields.invalidDate2.resolve).toBe(defaultTracingResolver)
-    expect(fields.invalidDate3.resolve).toBe(defaultTracingResolver)
-    expect(fields.invalidDate4.resolve).toBe(defaultTracingResolver)
-    expect(fields.invalidDate5.resolve).toBe(defaultTracingResolver)
-    expect(fields.invalidDate6.resolve).toBe(defaultTracingResolver)
-    expect(fields.invalidDate7.resolve).toBe(defaultTracingResolver)
+    expect(fields.invalidDate1.resolve).toBe(defaultResolver)
+    expect(fields.invalidDate2.resolve).toBe(defaultResolver)
+    expect(fields.invalidDate3.resolve).toBe(defaultResolver)
+    expect(fields.invalidDate4.resolve).toBe(defaultResolver)
+    expect(fields.invalidDate5.resolve).toBe(defaultResolver)
+    expect(fields.invalidDate6.resolve).toBe(defaultResolver)
+    expect(fields.invalidDate7.resolve).toBe(defaultResolver)
     expect(fields.invalidDate8).toBeUndefined()
-    expect(fields.invalidDate9.resolve).toBe(defaultTracingResolver)
+    expect(fields.invalidDate9.resolve).toBe(defaultResolver)
     expect(fields.invalidDate10).toBeUndefined()
-    expect(fields.invalidDate11.resolve).toBe(defaultTracingResolver)
+    expect(fields.invalidDate11.resolve).toBe(defaultResolver)
     expect(fields.invalidDate12).toBeUndefined()
     expect(fields.invalidDate13).toBeUndefined()
-    expect(fields.invalidDate14.resolve).toBe(defaultTracingResolver)
-    expect(fields.invalidDate15.resolve).toBe(defaultTracingResolver)
-    expect(fields.invalidDate16.resolve).toBe(defaultTracingResolver)
+    expect(fields.invalidDate14.resolve).toBe(defaultResolver)
+    expect(fields.invalidDate15.resolve).toBe(defaultResolver)
+    expect(fields.invalidDate16.resolve).toBe(defaultResolver)
   })
 
   it.each([