github.com/dgraph-io/dgraph@v1.2.8/graphql/resolve/resolver_error_test.go

/*
 * Copyright 2019 Dgraph Labs, Inc. and Contributors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package resolve

import (
	"context"
	"io/ioutil"
	"testing"

	dgoapi "github.com/dgraph-io/dgo/v2/protos/api"
	"github.com/dgraph-io/dgraph/gql"
	"github.com/dgraph-io/dgraph/graphql/schema"
	"github.com/dgraph-io/dgraph/graphql/test"
	"github.com/dgraph-io/dgraph/x"
	"github.com/google/go-cmp/cmp"
	"github.com/pkg/errors"
	"github.com/stretchr/testify/require"
	"gopkg.in/yaml.v2"
)

// Tests that result completion and GraphQL error propagation are working properly.

// All the tests work on a mocked json response, rather than a running Dgraph.
// It's better to mock the Dgraph client interface in these tests and have cases
// where one can directly see the json response and how it gets modified, than
// to try and orchestrate conditions for all these complicated tests in a live
// Dgraph instance.  Done on a real Dgraph, you also can't see the responses
// to see what the test is actually doing.

type executor struct {
	resp     string
	assigned map[string]string
	result   map[string]interface{}

	// start reporting Dgraph fails at this point (0 = never fail, 1 = fail on
	// first request, 2 = succeed once and then fail on 2nd request, etc.)
	failQuery    int
	failMutation int
}

type QueryCase struct {
	Name        string
	GQLQuery    string
	Explanation string
	Response    string // Dgraph json response
	Expected    string // Expected data from Resolve()
	Errors      x.GqlErrorList
}

var testGQLSchema = `
type Author {
	id: ID!
	name: String!
	dob: DateTime
	postsRequired: [Post!]!
	postsElmntRequired: [Post!]
	postsNullable: [Post]
	postsNullableListRequired: [Post]!
}

type Post {
	id: ID!
	title: String!
	text: String
	author: Author!
}`

func (ex *executor) Query(ctx context.Context, query *gql.GraphQuery) ([]byte, error) {
	ex.failQuery--
	if ex.failQuery == 0 {
		return nil, schema.GQLWrapf(errors.New("_bad stuff happend_"), "Dgraph query failed")
	}
	return []byte(ex.resp), nil
}

func (ex *executor) Mutate(ctx context.Context,
	query *gql.GraphQuery,
	mutations []*dgoapi.Mutation) (map[string]string, map[string]interface{}, error) {
	ex.failMutation--
	if ex.failMutation == 0 {
		return nil, nil, schema.GQLWrapf(errors.New("_bad stuff happend_"), "Dgraph mutation failed")
	}
	return ex.assigned, ex.result, nil
}

// Tests in resolver_test.yaml are about what gets into a completed result (addition
// of "null", errors and error propagation).  Exact JSON result (e.g. order) doesn't
// matter here - that makes for easier to format and read tests for these many cases.
//
// The []bytes built by Resolve() have some other properties, such as ordering of
// fields, which are tested by TestResponseOrder().
func TestResolver(t *testing.T) {
	b, err := ioutil.ReadFile("resolver_error_test.yaml")
	require.NoError(t, err, "Unable to read test file")

	var tests []QueryCase
	err = yaml.Unmarshal(b, &tests)
	require.NoError(t, err, "Unable to unmarshal tests to yaml.")

	gqlSchema := test.LoadSchemaFromString(t, testGQLSchema)

	for _, tcase := range tests {
		t.Run(tcase.Name, func(t *testing.T) {
			resp := resolve(gqlSchema, tcase.GQLQuery, tcase.Response)

			if diff := cmp.Diff(tcase.Errors, resp.Errors); diff != "" {
				t.Errorf("errors mismatch (-want +got):\n%s", diff)
			}

			require.JSONEq(t, tcase.Expected, resp.Data.String(), tcase.Explanation)
		})
	}
}

// Ordering of results and inserted null values matters in GraphQL:
// https://graphql.github.io/graphql-spec/June2018/#sec-Serialized-Map-Ordering
func TestResponseOrder(t *testing.T) {
	query := `query {
		 getAuthor(id: "0x1") {
			 name
			 dob
			 postsNullable {
				 title
				 text
			 }
		 }
	 }`

	tests := []QueryCase{
		{Name: "Response is in same order as GQL query",
			GQLQuery: query,
			Response: `{ "getAuthor": [ { "name": "A.N. Author", "dob": "2000-01-01", ` +
				`"postsNullable": [ ` +
				`{ "title": "A Title", "text": "Some Text" }, ` +
				`{ "title": "Another Title", "text": "More Text" } ] } ] }`,
			Expected: `{"getAuthor": {"name": "A.N. Author", "dob": "2000-01-01", ` +
				`"postsNullable": [` +
				`{"title": "A Title", "text": "Some Text"}, ` +
				`{"title": "Another Title", "text": "More Text"}]}}`},
		{Name: "Response is in same order as GQL query no matter Dgraph order",
			GQLQuery: query,
			Response: `{ "getAuthor": [ { "dob": "2000-01-01", "name": "A.N. Author", ` +
				`"postsNullable": [ ` +
				`{ "text": "Some Text", "title": "A Title" }, ` +
				`{ "title": "Another Title", "text": "More Text" } ] } ] }`,
			Expected: `{"getAuthor": {"name": "A.N. Author", "dob": "2000-01-01", ` +
				`"postsNullable": [` +
				`{"title": "A Title", "text": "Some Text"}, ` +
				`{"title": "Another Title", "text": "More Text"}]}}`},
		{Name: "Inserted null is in GQL query order",
			GQLQuery: query,
			Response: `{ "getAuthor": [ { "name": "A.N. Author", ` +
				`"postsNullable": [ ` +
				`{ "title": "A Title" }, ` +
				`{ "title": "Another Title", "text": "More Text" } ] } ] }`,
			Expected: `{"getAuthor": {"name": "A.N. Author", "dob": null, ` +
				`"postsNullable": [` +
				`{"title": "A Title", "text": null}, ` +
				`{"title": "Another Title", "text": "More Text"}]}}`},
	}

	gqlSchema := test.LoadSchemaFromString(t, testGQLSchema)

	for _, test := range tests {
		t.Run(test.Name, func(t *testing.T) {
			resp := resolve(gqlSchema, test.GQLQuery, test.Response)

			require.Nil(t, resp.Errors)
			require.Equal(t, test.Expected, resp.Data.String())
		})
	}
}

// For add and update mutations, we don't need to re-test all the cases from the
// query tests.  So just test enough to demonstrate that we'll catch it if we were
// to delete the call to completeDgraphResult before adding to the response.
func TestAddMutationUsesErrorPropagation(t *testing.T) {
	mutation := `mutation {
		addPost(input: [{title: "A Post", text: "Some text", author: {id: "0x1"}}]) {
			post {
				title
				text
				author {
					name
					dob
				}
			}
		}
	}`

	tests := map[string]struct {
		explanation   string
		mutResponse   map[string]string
		mutQryResp    map[string]interface{}
		queryResponse string
		expected      string
		errors        x.GqlErrorList
	}{
		"Add mutation adds missing nullable fields": {
			explanation: "Field 'dob' is nullable, so null should be inserted " +
				"if the mutation's query doesn't return a value.",
			mutResponse: map[string]string{"Post1": "0x2"},
			mutQryResp: map[string]interface{}{
				"Author2": []interface{}{map[string]string{"uid": "0x1"}}},
			queryResponse: `{ "post" : [
				{ "title": "A Post",
				"text": "Some text",
				"author": { "name": "A.N. Author" } } ] }`,
			expected: `{ "addPost": { "post" :
				[{ "title": "A Post",
				"text": "Some text",
				"author": { "name": "A.N. Author", "dob": null } }] } }`,
		},
		"Add mutation triggers GraphQL error propagation": {
			explanation: "An Author's name is non-nullable, so if that's missing, " +
				"the author is squashed to null, but that's also non-nullable, so the " +
				"propagates to the query root.",
			mutResponse: map[string]string{"Post1": "0x2"},
			mutQryResp: map[string]interface{}{
				"Author2": []interface{}{map[string]string{"uid": "0x1"}}},
			queryResponse: `{ "post" : [
				{ "title": "A Post",
				"text": "Some text",
				"author": { "dob": "2000-01-01" } } ] }`,
			expected: `{ "addPost": { "post" : [null] } }`,
			errors: x.GqlErrorList{&x.GqlError{
				Message: `Non-nullable field 'name' (type String!) ` +
					`was not present in result from Dgraph.  GraphQL error propagation triggered.`,
				Locations: []x.Location{{Column: 6, Line: 7}},
				Path:      []interface{}{"addPost", "post", 0, "author", "name"}}},
		},
	}

	gqlSchema := test.LoadSchemaFromString(t, testGQLSchema)

	for name, tcase := range tests {
		t.Run(name, func(t *testing.T) {
			resp := resolveWithClient(gqlSchema, mutation, nil,
				&executor{
					resp:     tcase.queryResponse,
					assigned: tcase.mutResponse,
					result:   tcase.mutQryResp,
				})

			test.RequireJSONEq(t, tcase.errors, resp.Errors)
			require.JSONEq(t, tcase.expected, resp.Data.String(), tcase.explanation)
		})
	}
}

func TestUpdateMutationUsesErrorPropagation(t *testing.T) {
	mutation := `mutation {
		updatePost(input: { filter: { id: ["0x1"] }, set: { text: "Some more text" } }) {
			post {
				title
				text
				author {
					name
					dob
				}
			}
		}
	}`

	// There's no need to have mocks for the mutation part here because with nil results all the
	// rewriting and rewriting from results will silently succeed.  All we care about the is the
	// result from the query that follows the mutation.  In that add case we have to satisfy
	// the type checking, but that's not required here.

	tests := map[string]struct {
		explanation   string
		mutResponse   map[string]string
		queryResponse string
		expected      string
		errors        x.GqlErrorList
	}{
		"Update Mutation adds missing nullable fields": {
			explanation: "Field 'dob' is nullable, so null should be inserted " +
				"if the mutation's query doesn't return a value.",
			queryResponse: `{ "post" : [
				{ "title": "A Post",
				"text": "Some text",
				"author": { "name": "A.N. Author" } } ] }`,
			expected: `{ "updatePost": { "post" :
				[{ "title": "A Post",
				"text": "Some text",
				"author": { "name": "A.N. Author", "dob": null } }] } }`,
		},
		"Update Mutation triggers GraphQL error propagation": {
			explanation: "An Author's name is non-nullable, so if that's missing, " +
				"the author is squashed to null, but that's also non-nullable, so the error " +
				"propagates to the query root.",
			queryResponse: `{ "post" : [ {
				"title": "A Post",
				"text": "Some text",
				"author": { "dob": "2000-01-01" } } ] }`,
			expected: `{ "updatePost": { "post" : [null] } }`,
			errors: x.GqlErrorList{&x.GqlError{
				Message: `Non-nullable field 'name' (type String!) ` +
					`was not present in result from Dgraph.  GraphQL error propagation triggered.`,
				Locations: []x.Location{{Column: 6, Line: 7}},
				Path:      []interface{}{"updatePost", "post", 0, "author", "name"}}},
		},
	}

	gqlSchema := test.LoadSchemaFromString(t, testGQLSchema)

	for name, tcase := range tests {
		t.Run(name, func(t *testing.T) {
			resp := resolveWithClient(gqlSchema, mutation, nil,
				&executor{resp: tcase.queryResponse, assigned: tcase.mutResponse})

			test.RequireJSONEq(t, tcase.errors, resp.Errors)
			require.JSONEq(t, tcase.expected, resp.Data.String(), tcase.explanation)
		})
	}
}

// TestManyMutationsWithError : Multiple mutations run serially (queries would
// run in parallel) and, in GraphQL, if an error is encountered in a request with
// multiple mutations, the mutations following the error are not run.  The mutations
// that have succeeded are permanent - i.e. not rolled back.
//
// There's no real way to test this E2E against a live instance because the only
// real fails during a mutation are either failure to communicate with Dgraph, or
// a bug that causes a query rewriting that Dgraph rejects.  There are some other
// cases: e.g. a delete that doesn't end up deleting anything (but we interpret
// that as not an error, it just deleted 0 things), and a mutation with some error
// in the input data/query (but that gets caught by validation before any mutations
// are executed).
//
// So this mocks a failing mutation and tests that we behave correctly in the case
// of multiple mutations.
func TestManyMutationsWithError(t *testing.T) {

	// add1 - should succeed
	// add2 - should fail
	// add3 - is never executed
	multiMutation := `mutation multipleMutations($id: ID!) {
			add1: addPost(input: [{title: "A Post", text: "Some text", author: {id: "0x1"}}]) {
				post { title }
			}

			add2: addPost(input: [{title: "A Post", text: "Some text", author: {id: $id}}]) {
				post { title }
			}

			add3: addPost(input: [{title: "A Post", text: "Some text", author: {id: "0x1"}}]) {
				post { title }
			}
		}`

	tests := map[string]struct {
		explanation   string
		idValue       string
		mutResponse   map[string]string
		mutQryResp    map[string]interface{}
		queryResponse string
		expected      string
		errors        x.GqlErrorList
	}{
		"Dgraph fail": {
			explanation: "a Dgraph, network or error in rewritten query failed the mutation",
			idValue:     "0x1",
			mutResponse: map[string]string{"Post1": "0x2"},
			mutQryResp: map[string]interface{}{
				"Author2": []interface{}{map[string]string{"uid": "0x1"}}},
			queryResponse: `{ "post" : [{ "title": "A Post" } ] }`,
			expected: `{
				"add1": { "post": [{ "title": "A Post" }] },
				"add2" : null
			}`,
			errors: x.GqlErrorList{
				&x.GqlError{Message: `mutation addPost failed because ` +
					`Dgraph mutation failed because _bad stuff happend_`,
					Locations: []x.Location{{Line: 6, Column: 4}}},
				&x.GqlError{Message: `Mutation add3 was not executed because of ` +
					`a previous error.`,
					Locations: []x.Location{{Line: 10, Column: 4}}}},
		},
		"Rewriting error": {
			explanation: "The reference ID is not a uint64, so can't be converted to a uid",
			idValue:     "hi",
			mutResponse: map[string]string{"Post1": "0x2"},
			mutQryResp: map[string]interface{}{
				"Author2": []interface{}{map[string]string{"uid": "0x1"}}},
			queryResponse: `{ "post" : [{ "title": "A Post" } ] }`,
			expected: `{
				"add1": { "post": [{ "title": "A Post" }] },
				"add2" : null
			}`,
			errors: x.GqlErrorList{
				&x.GqlError{Message: `couldn't rewrite mutation addPost because ` +
					`failed to rewrite mutation payload because ` +
					`ID argument (hi) was not able to be parsed`},
				&x.GqlError{Message: `Mutation add3 was not executed because of ` +
					`a previous error.`,
					Locations: []x.Location{{Line: 10, Column: 4}}}},
		},
	}

	gqlSchema := test.LoadSchemaFromString(t, testGQLSchema)

	for name, tcase := range tests {
		t.Run(name, func(t *testing.T) {

			resp := resolveWithClient(
				gqlSchema,
				multiMutation,
				map[string]interface{}{"id": tcase.idValue},
				&executor{
					resp:         tcase.queryResponse,
					assigned:     tcase.mutResponse,
					failMutation: 2})

			if diff := cmp.Diff(tcase.errors, resp.Errors); diff != "" {
				t.Errorf("errors mismatch (-want +got):\n%s", diff)
			}
			require.JSONEq(t, tcase.expected, resp.Data.String())
		})
	}
}

func resolve(gqlSchema schema.Schema, gqlQuery string, dgResponse string) *schema.Response {
	return resolveWithClient(gqlSchema, gqlQuery, nil, &executor{resp: dgResponse})
}

func resolveWithClient(
	gqlSchema schema.Schema,
	gqlQuery string,
	vars map[string]interface{},
	ex *executor) *schema.Response {
	resolver := New(
		gqlSchema,
		NewResolverFactory(nil, nil).WithConventionResolvers(gqlSchema, &ResolverFns{
			Qrw: NewQueryRewriter(),
			Arw: NewAddRewriter,
			Urw: NewUpdateRewriter,
			Qe:  ex,
			Me:  ex,
		}))

	return resolver.Resolve(context.Background(), &schema.Request{Query: gqlQuery, Variables: vars})
}