Improve GraphQL query for TypeScript (#710)

src/github/graphql.ts

@@ -1,17 +1,30 @@
-import { GitHubAPI, Headers, Variables } from './'
+import {
+  GitHubAPI,
+  Headers,
+  Variables
+} from './'
 
-class GraphQLError extends Error {
-  public query: string
-  public variables: Variables
+export interface GraphQLError {
+  message: string,
+  locations?: Array<{ line: number, column: number }>,
+  path?: Array<string | number>,
+  extensions?: {
+    [key: string]: any
+  }
+}
 
-  constructor (errors: Error[], query: string, variables: Variables) {
-    super(JSON.stringify(errors))
-    this.name = 'GraphQLError'
-    this.query = query
-    this.variables = variables
+export class GraphQLQueryError extends Error {
+  constructor (
+    public errors: GraphQLError[],
+    public query: string,
+    public variables: Variables,
+    public data: any
+  ) {
+    super(`Error(s) occurred executing GraphQL query:\n${JSON.stringify(errors, null, 2)}`)
+    this.name = 'GraphQLQueryError'
 
     if (Error.captureStackTrace) {
-      Error.captureStackTrace(this, GraphQLError)
+      Error.captureStackTrace(this, GraphQLQueryError)
     }
   }
 }
@@ -35,8 +48,13 @@ async function graphql (client: GitHubAPI, query: string, variables: Variables,
     variables
   })
 
-  if (res.data.errors) {
-    throw new GraphQLError(res.data.errors, query, variables)
+  if (res.data.errors && res.data.errors.length > 0) {
+    throw new GraphQLQueryError(
+      res.data.errors,
+      query,
+      variables,
+      res.data.data
+    )
   }
 
   return res.data.data

src/github/index.ts

@@ -58,7 +58,7 @@ export interface GitHubAPI extends Octokit {
   }
 
   request: (RequestOptions: RequestOptions) => Promise<Octokit.AnyResponse>
-  query: (query: string, variables?: Variables, headers?: Headers) => Promise<GraphQLResponse>
+  query: (query: string, variables?: Variables, headers?: Headers) => Promise<any>
 }
 
 export interface Headers {
@@ -67,6 +67,4 @@ export interface Headers {
 
 export interface Variables { [key: string]: any }
 
-export interface GraphQLResponse {
-  data: any
-}
+export { GraphQLError, GraphQLQueryError } from './graphql'

test/github/graphql.test.ts

@@ -69,12 +69,24 @@ describe('github/graphql', () => {
     })
 
     test('raises errors', async () => {
-      const response = { 'data': null, 'errors': [{ 'message': 'Unexpected end of document' }] }
+      const response = { 'data': 'some data', 'errors': [{ 'message': 'Unexpected end of document' }] }
 
       nock('https://api.github.com').post('/graphql', { query })
         .reply(200, response)
 
-      await expect(github.query(query)).rejects.toThrow('Unexpected end of document')
+      let thrownError
+      try {
+        await github.query(query)
+      } catch (err) {
+        thrownError = err
+      }
+
+      expect(thrownError).not.toBeUndefined()
+      expect(thrownError.name).toEqual('GraphQLQueryError')
+      expect(thrownError.toString()).toContain('Unexpected end of document')
+      expect(thrownError.query).toEqual(query)
+      expect(thrownError.errors).toEqual(response.errors)
+      expect(thrownError.data).toEqual('some data')
     })
   })