Add GraphQL Extensions (#184)

This enables accessing the Extensions field, as defined in the response
format: https://spec.graphql.org/October2021/#sec-Response-Format

Extensions can be enabled using configuration option use_extensions.
This will change the return parameters of the generated client
functions. Making it a breaking change if enabled.

Since extensions are untyped as defined in the spec, the Client will
return an interface of type map[string]interface{}.

internal/integration/generated.go

@@ -2995,6 +2995,30 @@ func (v *queryWithVariablesUser) GetName() string { return v.Name }
 // GetLuckyNumber returns queryWithVariablesUser.LuckyNumber, and is useful for accessing the field via an interface.
 func (v *queryWithVariablesUser) GetLuckyNumber() int { return v.LuckyNumber }
 
+// simpleQueryExtMeUser includes the requested fields of the GraphQL type User.
+type simpleQueryExtMeUser struct {
+	Id          string `json:"id"`
+	Name        string `json:"name"`
+	LuckyNumber int    `json:"luckyNumber"`
+}
+
+// GetId returns simpleQueryExtMeUser.Id, and is useful for accessing the field via an interface.
+func (v *simpleQueryExtMeUser) GetId() string { return v.Id }
+
+// GetName returns simpleQueryExtMeUser.Name, and is useful for accessing the field via an interface.
+func (v *simpleQueryExtMeUser) GetName() string { return v.Name }
+
+// GetLuckyNumber returns simpleQueryExtMeUser.LuckyNumber, and is useful for accessing the field via an interface.
+func (v *simpleQueryExtMeUser) GetLuckyNumber() int { return v.LuckyNumber }
+
+// simpleQueryExtResponse is returned by simpleQueryExt on success.
+type simpleQueryExtResponse struct {
+	Me simpleQueryExtMeUser `json:"me"`
+}
+
+// GetMe returns simpleQueryExtResponse.Me, and is useful for accessing the field via an interface.
+func (v *simpleQueryExtResponse) GetMe() simpleQueryExtMeUser { return v.Me }
+
 // simpleQueryMeUser includes the requested fields of the GraphQL type User.
 type simpleQueryMeUser struct {
 	Id          string `json:"id"`
@@ -3022,14 +3046,10 @@ func (v *simpleQueryResponse) GetMe() simpleQueryMeUser { return v.Me }
 func failingQuery(
 	ctx context.Context,
 	client graphql.Client,
-) (*failingQueryResponse, error) {
-	var err error
-
-	var retval failingQueryResponse
-	err = client.MakeRequest(
-		ctx,
-		"failingQuery",
-		`
+) (*failingQueryResponse, map[string]interface{}, error) {
+	req := &graphql.Request{
+		OpName: "failingQuery",
+		Query: `
 query failingQuery {
 	fail
 	me {
@@ -3037,27 +3057,29 @@ query failingQuery {
 	}
 }
 `,
-		&retval,
-		nil,
+	}
+	var err error
+
+	var data failingQueryResponse
+	resp := &graphql.Response{Data: &data}
+
+	err = client.MakeRequest(
+		ctx,
+		req,
+		resp,
 	)
-	return &retval, err
+
+	return &data, resp.Extensions, err
 }
 
 func queryWithCustomMarshal(
 	ctx context.Context,
 	client graphql.Client,
 	date time.Time,
-) (*queryWithCustomMarshalResponse, error) {
-	__input := __queryWithCustomMarshalInput{
-		Date: date,
-	}
-	var err error
-
-	var retval queryWithCustomMarshalResponse
-	err = client.MakeRequest(
-		ctx,
-		"queryWithCustomMarshal",
-		`
+) (*queryWithCustomMarshalResponse, map[string]interface{}, error) {
+	req := &graphql.Request{
+		OpName: "queryWithCustomMarshal",
+		Query: `
 query queryWithCustomMarshal ($date: Date!) {
 	usersBornOn(date: $date) {
 		id
@@ -3066,10 +3088,22 @@ query queryWithCustomMarshal ($date: Date!) {
 	}
 }
 `,
-		&retval,
-		&__input,
+		Variables: &__queryWithCustomMarshalInput{
+			Date: date,
+		},
+	}
+	var err error
+
+	var data queryWithCustomMarshalResponse
+	resp := &graphql.Response{Data: &data}
+
+	err = client.MakeRequest(
+		ctx,
+		req,
+		resp,
 	)
-	return &retval, err
+
+	return &data, resp.Extensions, err
 }
 
 func queryWithCustomMarshalOptional(
@@ -3077,18 +3111,10 @@ func queryWithCustomMarshalOptional(
 	client graphql.Client,
 	date *time.Time,
 	id *string,
-) (*queryWithCustomMarshalOptionalResponse, error) {
-	__input := __queryWithCustomMarshalOptionalInput{
-		Date: date,
-		Id:   id,
-	}
-	var err error
-
-	var retval queryWithCustomMarshalOptionalResponse
-	err = client.MakeRequest(
-		ctx,
-		"queryWithCustomMarshalOptional",
-		`
+) (*queryWithCustomMarshalOptionalResponse, map[string]interface{}, error) {
+	req := &graphql.Request{
+		OpName: "queryWithCustomMarshalOptional",
+		Query: `
 query queryWithCustomMarshalOptional ($date: Date, $id: ID) {
 	userSearch(birthdate: $date, id: $id) {
 		id
@@ -3097,27 +3123,33 @@ query queryWithCustomMarshalOptional ($date: Date, $id: ID) {
 	}
 }
 `,
-		&retval,
-		&__input,
+		Variables: &__queryWithCustomMarshalOptionalInput{
+			Date: date,
+			Id:   id,
+		},
+	}
+	var err error
+
+	var data queryWithCustomMarshalOptionalResponse
+	resp := &graphql.Response{Data: &data}
+
+	err = client.MakeRequest(
+		ctx,
+		req,
+		resp,
 	)
-	return &retval, err
+
+	return &data, resp.Extensions, err
 }
 
 func queryWithCustomMarshalSlice(
 	ctx context.Context,
 	client graphql.Client,
 	dates []time.Time,
-) (*queryWithCustomMarshalSliceResponse, error) {
-	__input := __queryWithCustomMarshalSliceInput{
-		Dates: dates,
-	}
-	var err error
-
-	var retval queryWithCustomMarshalSliceResponse
-	err = client.MakeRequest(
-		ctx,
-		"queryWithCustomMarshalSlice",
-		`
+) (*queryWithCustomMarshalSliceResponse, map[string]interface{}, error) {
+	req := &graphql.Request{
+		OpName: "queryWithCustomMarshalSlice",
+		Query: `
 query queryWithCustomMarshalSlice ($dates: [Date!]!) {
 	usersBornOnDates(dates: $dates) {
 		id
@@ -3126,27 +3158,32 @@ query queryWithCustomMarshalSlice ($dates: [Date!]!) {
 	}
 }
 `,
-		&retval,
-		&__input,
+		Variables: &__queryWithCustomMarshalSliceInput{
+			Dates: dates,
+		},
+	}
+	var err error
+
+	var data queryWithCustomMarshalSliceResponse
+	resp := &graphql.Response{Data: &data}
+
+	err = client.MakeRequest(
+		ctx,
+		req,
+		resp,
 	)
-	return &retval, err
+
+	return &data, resp.Extensions, err
 }
 
 func queryWithFlatten(
 	ctx context.Context,
 	client graphql.Client,
 	ids []string,
-) (*QueryFragment, error) {
-	__input := __queryWithFlattenInput{
-		Ids: ids,
-	}
-	var err error
-
-	var retval QueryFragment
-	err = client.MakeRequest(
-		ctx,
-		"queryWithFlatten",
-		`
+) (*QueryFragment, map[string]interface{}, error) {
+	req := &graphql.Request{
+		OpName: "queryWithFlatten",
+		Query: `
 query queryWithFlatten ($ids: [ID!]!) {
 	... QueryFragment
 }
@@ -3189,27 +3226,32 @@ fragment FriendsFields on User {
 	name
 }
 `,
-		&retval,
-		&__input,
+		Variables: &__queryWithFlattenInput{
+			Ids: ids,
+		},
+	}
+	var err error
+
+	var data QueryFragment
+	resp := &graphql.Response{Data: &data}
+
+	err = client.MakeRequest(
+		ctx,
+		req,
+		resp,
 	)
-	return &retval, err
+
+	return &data, resp.Extensions, err
 }
 
 func queryWithFragments(
 	ctx context.Context,
 	client graphql.Client,
 	ids []string,
-) (*queryWithFragmentsResponse, error) {
-	__input := __queryWithFragmentsInput{
-		Ids: ids,
-	}
-	var err error
-
-	var retval queryWithFragmentsResponse
-	err = client.MakeRequest(
-		ctx,
-		"queryWithFragments",
-		`
+) (*queryWithFragmentsResponse, map[string]interface{}, error) {
+	req := &graphql.Request{
+		OpName: "queryWithFragments",
+		Query: `
 query queryWithFragments ($ids: [ID!]!) {
 	beings(ids: $ids) {
 		__typename
@@ -3246,27 +3288,32 @@ query queryWithFragments ($ids: [ID!]!) {
 	}
 }
 `,
-		&retval,
-		&__input,
+		Variables: &__queryWithFragmentsInput{
+			Ids: ids,
+		},
+	}
+	var err error
+
+	var data queryWithFragmentsResponse
+	resp := &graphql.Response{Data: &data}
+
+	err = client.MakeRequest(
+		ctx,
+		req,
+		resp,
 	)
-	return &retval, err
+
+	return &data, resp.Extensions, err
 }
 
 func queryWithInterfaceListField(
 	ctx context.Context,
 	client graphql.Client,
 	ids []string,
-) (*queryWithInterfaceListFieldResponse, error) {
-	__input := __queryWithInterfaceListFieldInput{
-		Ids: ids,
-	}
-	var err error
-
-	var retval queryWithInterfaceListFieldResponse
-	err = client.MakeRequest(
-		ctx,
-		"queryWithInterfaceListField",
-		`
+) (*queryWithInterfaceListFieldResponse, map[string]interface{}, error) {
+	req := &graphql.Request{
+		OpName: "queryWithInterfaceListField",
+		Query: `
 query queryWithInterfaceListField ($ids: [ID!]!) {
 	beings(ids: $ids) {
 		__typename
@@ -3275,27 +3322,32 @@ query queryWithInterfaceListField ($ids: [ID!]!) {
 	}
 }
 `,
-		&retval,
-		&__input,
+		Variables: &__queryWithInterfaceListFieldInput{
+			Ids: ids,
+		},
+	}
+	var err error
+
+	var data queryWithInterfaceListFieldResponse
+	resp := &graphql.Response{Data: &data}
+
+	err = client.MakeRequest(
+		ctx,
+		req,
+		resp,
 	)
-	return &retval, err
+
+	return &data, resp.Extensions, err
 }
 
 func queryWithInterfaceListPointerField(
 	ctx context.Context,
 	client graphql.Client,
 	ids []string,
-) (*queryWithInterfaceListPointerFieldResponse, error) {
-	__input := __queryWithInterfaceListPointerFieldInput{
-		Ids: ids,
-	}
-	var err error
-
-	var retval queryWithInterfaceListPointerFieldResponse
-	err = client.MakeRequest(
-		ctx,
-		"queryWithInterfaceListPointerField",
-		`
+) (*queryWithInterfaceListPointerFieldResponse, map[string]interface{}, error) {
+	req := &graphql.Request{
+		OpName: "queryWithInterfaceListPointerField",
+		Query: `
 query queryWithInterfaceListPointerField ($ids: [ID!]!) {
 	beings(ids: $ids) {
 		__typename
@@ -3304,27 +3356,32 @@ query queryWithInterfaceListPointerField ($ids: [ID!]!) {
 	}
 }
 `,
-		&retval,
-		&__input,
+		Variables: &__queryWithInterfaceListPointerFieldInput{
+			Ids: ids,
+		},
+	}
+	var err error
+
+	var data queryWithInterfaceListPointerFieldResponse
+	resp := &graphql.Response{Data: &data}
+
+	err = client.MakeRequest(
+		ctx,
+		req,
+		resp,
 	)
-	return &retval, err
+
+	return &data, resp.Extensions, err
 }
 
 func queryWithInterfaceNoFragments(
 	ctx context.Context,
 	client graphql.Client,
 	id string,
-) (*queryWithInterfaceNoFragmentsResponse, error) {
-	__input := __queryWithInterfaceNoFragmentsInput{
-		Id: id,
-	}
-	var err error
-
-	var retval queryWithInterfaceNoFragmentsResponse
-	err = client.MakeRequest(
-		ctx,
-		"queryWithInterfaceNoFragments",
-		`
+) (*queryWithInterfaceNoFragmentsResponse, map[string]interface{}, error) {
+	req := &graphql.Request{
+		OpName: "queryWithInterfaceNoFragments",
+		Query: `
 query queryWithInterfaceNoFragments ($id: ID!) {
 	being(id: $id) {
 		__typename
@@ -3337,27 +3394,32 @@ query queryWithInterfaceNoFragments ($id: ID!) {
 	}
 }
 `,
-		&retval,
-		&__input,
+		Variables: &__queryWithInterfaceNoFragmentsInput{
+			Id: id,
+		},
+	}
+	var err error
+
+	var data queryWithInterfaceNoFragmentsResponse
+	resp := &graphql.Response{Data: &data}
+
+	err = client.MakeRequest(
+		ctx,
+		req,
+		resp,
 	)
-	return &retval, err
+
+	return &data, resp.Extensions, err
 }
 
 func queryWithNamedFragments(
 	ctx context.Context,
 	client graphql.Client,
 	ids []string,
-) (*queryWithNamedFragmentsResponse, error) {
-	__input := __queryWithNamedFragmentsInput{
-		Ids: ids,
-	}
-	var err error
-
-	var retval queryWithNamedFragmentsResponse
-	err = client.MakeRequest(
-		ctx,
-		"queryWithNamedFragments",
-		`
+) (*queryWithNamedFragmentsResponse, map[string]interface{}, error) {
+	req := &graphql.Request{
+		OpName: "queryWithNamedFragments",
+		Query: `
 query queryWithNamedFragments ($ids: [ID!]!) {
 	beings(ids: $ids) {
 		__typename
@@ -3394,27 +3456,32 @@ fragment MoreUserFields on User {
 	}
 }
 `,
-		&retval,
-		&__input,
+		Variables: &__queryWithNamedFragmentsInput{
+			Ids: ids,
+		},
+	}
+	var err error
+
+	var data queryWithNamedFragmentsResponse
+	resp := &graphql.Response{Data: &data}
+
+	err = client.MakeRequest(
+		ctx,
+		req,
+		resp,
 	)
-	return &retval, err
+
+	return &data, resp.Extensions, err
 }
 
 func queryWithOmitempty(
 	ctx context.Context,
 	client graphql.Client,
 	id string,
-) (*queryWithOmitemptyResponse, error) {
-	__input := __queryWithOmitemptyInput{
-		Id: id,
-	}
-	var err error
-
-	var retval queryWithOmitemptyResponse
-	err = client.MakeRequest(
-		ctx,
-		"queryWithOmitempty",
-		`
+) (*queryWithOmitemptyResponse, map[string]interface{}, error) {
+	req := &graphql.Request{
+		OpName: "queryWithOmitempty",
+		Query: `
 query queryWithOmitempty ($id: ID) {
 	user(id: $id) {
 		id
@@ -3423,27 +3490,32 @@ query queryWithOmitempty ($id: ID) {
 	}
 }
 `,
-		&retval,
-		&__input,
+		Variables: &__queryWithOmitemptyInput{
+			Id: id,
+		},
+	}
+	var err error
+
+	var data queryWithOmitemptyResponse
+	resp := &graphql.Response{Data: &data}
+
+	err = client.MakeRequest(
+		ctx,
+		req,
+		resp,
 	)
-	return &retval, err
+
+	return &data, resp.Extensions, err
 }
 
 func queryWithVariables(
 	ctx context.Context,
 	client graphql.Client,
 	id string,
-) (*queryWithVariablesResponse, error) {
-	__input := __queryWithVariablesInput{
-		Id: id,
-	}
-	var err error
-
-	var retval queryWithVariablesResponse
-	err = client.MakeRequest(
-		ctx,
-		"queryWithVariables",
-		`
+) (*queryWithVariablesResponse, map[string]interface{}, error) {
+	req := &graphql.Request{
+		OpName: "queryWithVariables",
+		Query: `
 query queryWithVariables ($id: ID!) {
 	user(id: $id) {
 		id
@@ -3452,23 +3524,31 @@ query queryWithVariables ($id: ID!) {
 	}
 }
 `,
-		&retval,
-		&__input,
+		Variables: &__queryWithVariablesInput{
+			Id: id,
+		},
+	}
+	var err error
+
+	var data queryWithVariablesResponse
+	resp := &graphql.Response{Data: &data}
+
+	err = client.MakeRequest(
+		ctx,
+		req,
+		resp,
 	)
-	return &retval, err
+
+	return &data, resp.Extensions, err
 }
 
 func simpleQuery(
 	ctx context.Context,
 	client graphql.Client,
-) (*simpleQueryResponse, error) {
-	var err error
-
-	var retval simpleQueryResponse
-	err = client.MakeRequest(
-		ctx,
-		"simpleQuery",
-		`
+) (*simpleQueryResponse, map[string]interface{}, error) {
+	req := &graphql.Request{
+		OpName: "simpleQuery",
+		Query: `
 query simpleQuery {
 	me {
 		id
@@ -3477,8 +3557,47 @@ query simpleQuery {
 	}
 }
 `,
-		&retval,
-		nil,
+	}
+	var err error
+
+	var data simpleQueryResponse
+	resp := &graphql.Response{Data: &data}
+
+	err = client.MakeRequest(
+		ctx,
+		req,
+		resp,
 	)
-	return &retval, err
+
+	return &data, resp.Extensions, err
+}
+
+func simpleQueryExt(
+	ctx context.Context,
+	client graphql.Client,
+) (*simpleQueryExtResponse, map[string]interface{}, error) {
+	req := &graphql.Request{
+		OpName: "simpleQueryExt",
+		Query: `
+query simpleQueryExt {
+	me {
+		id
+		name
+		luckyNumber
+	}
+}
+`,
+	}
+	var err error
+
+	var data simpleQueryExtResponse
+	resp := &graphql.Response{Data: &data}
+
+	err = client.MakeRequest(
+		ctx,
+		req,
+		resp,
+	)
+
+	return &data, resp.Extensions, err
 }

internal/integration/genqlient.yaml

@@ -2,6 +2,7 @@ schema: schema.graphql
 operations: "*_test.go"
 generated: generated.go
 allow_broken_features: true
+use_extensions: true
 bindings:
   Date:
     type: time.Time

internal/integration/integration_test.go

@@ -27,7 +27,7 @@ func TestSimpleQuery(t *testing.T) {
 	defer server.Close()
 	client := newRoundtripClient(t, server.URL)
 
-	resp, err := simpleQuery(ctx, client)
+	resp, _, err := simpleQuery(ctx, client)
 	require.NoError(t, err)
 
 	assert.Equal(t, "1", resp.Me.Id)
@@ -44,7 +44,7 @@ func TestServerError(t *testing.T) {
 	defer server.Close()
 	client := newRoundtripClient(t, server.URL)
 
-	resp, err := failingQuery(ctx, client)
+	resp, _, err := failingQuery(ctx, client)
 	// As long as we get some response back, we should still return a full
 	// response -- and indeed in this case it should even have another field
 	// (which didn't err) set.
@@ -57,7 +57,7 @@ func TestNetworkError(t *testing.T) {
 	ctx := context.Background()
 	client := newRoundtripClient(t, "https://nothing.invalid/graphql")
 
-	resp, err := failingQuery(ctx, client)
+	resp, _, err := failingQuery(ctx, client)
 	// As we guarantee in the README, even on network error you always get a
 	// non-nil response; this is so you can write e.g.
 	//	resp, err := failingQuery(ctx)
@@ -82,19 +82,34 @@ func TestVariables(t *testing.T) {
 	// worry about it.
 	client := graphql.NewClient(server.URL, http.DefaultClient)
 
-	resp, err := queryWithVariables(ctx, client, "2")
+	resp, _, err := queryWithVariables(ctx, client, "2")
 	require.NoError(t, err)
 
 	assert.Equal(t, "2", resp.User.Id)
 	assert.Equal(t, "Raven", resp.User.Name)
 	assert.Equal(t, -1, resp.User.LuckyNumber)
 
-	resp, err = queryWithVariables(ctx, client, "374892379482379")
+	resp, _, err = queryWithVariables(ctx, client, "374892379482379")
 	require.NoError(t, err)
 
 	assert.Zero(t, resp.User)
 }
 
+func TestExtensions(t *testing.T) {
+	_ = `# @genqlient
+	query simpleQueryExt { me { id name luckyNumber } }`
+
+	ctx := context.Background()
+	server := server.RunServer()
+	defer server.Close()
+	client := newRoundtripClient(t, server.URL)
+
+	_, extensions, err := simpleQueryExt(ctx, client)
+	require.NoError(t, err)
+	assert.NotNil(t, extensions)
+	assert.Equal(t, extensions["foobar"], "test")
+}
+
 func TestOmitempty(t *testing.T) {
 	_ = `# @genqlient(omitempty: true)
 	query queryWithOmitempty($id: ID) {
@@ -106,7 +121,7 @@ func TestOmitempty(t *testing.T) {
 	defer server.Close()
 	client := newRoundtripClient(t, server.URL)
 
-	resp, err := queryWithOmitempty(ctx, client, "2")
+	resp, _, err := queryWithOmitempty(ctx, client, "2")
 	require.NoError(t, err)
 
 	assert.Equal(t, "2", resp.User.Id)
@@ -114,7 +129,7 @@ func TestOmitempty(t *testing.T) {
 	assert.Equal(t, -1, resp.User.LuckyNumber)
 
 	// should return default user, not the user with ID ""
-	resp, err = queryWithOmitempty(ctx, client, "")
+	resp, _, err = queryWithOmitempty(ctx, client, "")
 	require.NoError(t, err)
 
 	assert.Equal(t, "1", resp.User.Id)
@@ -133,7 +148,7 @@ func TestCustomMarshal(t *testing.T) {
 	defer server.Close()
 	client := newRoundtripClient(t, server.URL)
 
-	resp, err := queryWithCustomMarshal(ctx, client,
+	resp, _, err := queryWithCustomMarshal(ctx, client,
 		time.Date(2025, time.January, 1, 12, 34, 56, 789, time.UTC))
 	require.NoError(t, err)
 
@@ -145,7 +160,7 @@ func TestCustomMarshal(t *testing.T) {
 		time.Date(2025, time.January, 1, 0, 0, 0, 0, time.UTC),
 		user.Birthdate)
 
-	resp, err = queryWithCustomMarshal(ctx, client,
+	resp, _, err = queryWithCustomMarshal(ctx, client,
 		time.Date(2021, time.January, 1, 12, 34, 56, 789, time.UTC))
 	require.NoError(t, err)
 	assert.Len(t, resp.UsersBornOn, 0)
@@ -162,7 +177,7 @@ func TestCustomMarshalSlice(t *testing.T) {
 	defer server.Close()
 	client := newRoundtripClient(t, server.URL)
 
-	resp, err := queryWithCustomMarshalSlice(ctx, client,
+	resp, _, err := queryWithCustomMarshalSlice(ctx, client,
 		[]time.Time{time.Date(2025, time.January, 1, 12, 34, 56, 789, time.UTC)})
 	require.NoError(t, err)
 
@@ -174,7 +189,7 @@ func TestCustomMarshalSlice(t *testing.T) {
 		time.Date(2025, time.January, 1, 0, 0, 0, 0, time.UTC),
 		user.Birthdate)
 
-	resp, err = queryWithCustomMarshalSlice(ctx, client,
+	resp, _, err = queryWithCustomMarshalSlice(ctx, client,
 		[]time.Time{time.Date(2021, time.January, 1, 12, 34, 56, 789, time.UTC)})
 	require.NoError(t, err)
 	assert.Len(t, resp.UsersBornOnDates, 0)
@@ -197,7 +212,7 @@ func TestCustomMarshalOptional(t *testing.T) {
 	client := newRoundtripClient(t, server.URL)
 
 	date := time.Date(2025, time.January, 1, 12, 34, 56, 789, time.UTC)
-	resp, err := queryWithCustomMarshalOptional(ctx, client, &date, nil)
+	resp, _, err := queryWithCustomMarshalOptional(ctx, client, &date, nil)
 	require.NoError(t, err)
 
 	assert.Len(t, resp.UserSearch, 1)
@@ -209,7 +224,7 @@ func TestCustomMarshalOptional(t *testing.T) {
 		user.Birthdate)
 
 	id := "2"
-	resp, err = queryWithCustomMarshalOptional(ctx, client, nil, &id)
+	resp, _, err = queryWithCustomMarshalOptional(ctx, client, nil, &id)
 	require.NoError(t, err)
 	assert.Len(t, resp.UserSearch, 1)
 	user = resp.UserSearch[0]
@@ -230,7 +245,7 @@ func TestInterfaceNoFragments(t *testing.T) {
 	defer server.Close()
 	client := newRoundtripClient(t, server.URL)
 
-	resp, err := queryWithInterfaceNoFragments(ctx, client, "1")
+	resp, _, err := queryWithInterfaceNoFragments(ctx, client, "1")
 	require.NoError(t, err)
 
 	// We should get the following response:
@@ -250,7 +265,7 @@ func TestInterfaceNoFragments(t *testing.T) {
 	assert.Equal(t, "1", user.Id)
 	assert.Equal(t, "Yours Truly", user.Name)
 
-	resp, err = queryWithInterfaceNoFragments(ctx, client, "3")
+	resp, _, err = queryWithInterfaceNoFragments(ctx, client, "3")
 	require.NoError(t, err)
 
 	// We should get the following response:
@@ -269,7 +284,7 @@ func TestInterfaceNoFragments(t *testing.T) {
 	assert.Equal(t, "3", animal.Id)
 	assert.Equal(t, "Fido", animal.Name)
 
-	resp, err = queryWithInterfaceNoFragments(ctx, client, "4757233945723")
+	resp, _, err = queryWithInterfaceNoFragments(ctx, client, "4757233945723")
 	require.NoError(t, err)
 
 	// We should get the following response:
@@ -293,7 +308,7 @@ func TestInterfaceListField(t *testing.T) {
 	defer server.Close()
 	client := newRoundtripClient(t, server.URL)
 
-	resp, err := queryWithInterfaceListField(ctx, client,
+	resp, _, err := queryWithInterfaceListField(ctx, client,
 		[]string{"1", "3", "12847394823"})
 	require.NoError(t, err)
 
@@ -340,7 +355,7 @@ func TestInterfaceListPointerField(t *testing.T) {
 	defer server.Close()
 	client := newRoundtripClient(t, server.URL)
 
-	resp, err := queryWithInterfaceListPointerField(ctx, client,
+	resp, _, err := queryWithInterfaceListPointerField(ctx, client,
 		[]string{"1", "3", "12847394823"})
 	require.NoError(t, err)
 
@@ -394,7 +409,7 @@ func TestFragments(t *testing.T) {
 	defer server.Close()
 	client := newRoundtripClient(t, server.URL)
 
-	resp, err := queryWithFragments(ctx, client, []string{"1", "3", "12847394823"})
+	resp, _, err := queryWithFragments(ctx, client, []string{"1", "3", "12847394823"})
 	require.NoError(t, err)
 
 	require.Len(t, resp.Beings, 3)
@@ -487,7 +502,7 @@ func TestNamedFragments(t *testing.T) {
 	defer server.Close()
 	client := newRoundtripClient(t, server.URL)
 
-	resp, err := queryWithNamedFragments(ctx, client, []string{"1", "3", "12847394823"})
+	resp, _, err := queryWithNamedFragments(ctx, client, []string{"1", "3", "12847394823"})
 	require.NoError(t, err)
 
 	require.Len(t, resp.Beings, 3)
@@ -616,7 +631,7 @@ func TestFlatten(t *testing.T) {
 	defer server.Close()
 	client := newRoundtripClient(t, server.URL)
 
-	resp, err := queryWithFlatten(ctx, client, []string{"1", "3", "12847394823"})
+	resp, _, err := queryWithFlatten(ctx, client, []string{"1", "3", "12847394823"})
 	require.NoError(t, err)
 
 	require.Len(t, resp.Beings, 3)

internal/integration/roundtrip.go

@@ -88,16 +88,16 @@ func (c *roundtripClient) roundtripResponse(resp interface{}) {
 	assert.Equal(c.t, string(body), string(bodyAgain))
 }
 
-func (c *roundtripClient) MakeRequest(ctx context.Context, opName, query string, retval, variables interface{}) error {
+func (c *roundtripClient) MakeRequest(ctx context.Context, req *graphql.Request, resp *graphql.Response) error {
 	// TODO(benkraft): Also check the variables round-trip.  This is a bit less
 	// important since most of the code is the same (and input types are
 	// strictly simpler), and a bit hard to do because when asserting about
 	// structs we need to worry about things like equality of time.Time values.
-	err := c.wrapped.MakeRequest(ctx, opName, query, retval, variables)
+	err := c.wrapped.MakeRequest(ctx, req, resp)
 	if err != nil {
 		return err
 	}
-	c.roundtripResponse(retval)
+	c.roundtripResponse(resp.Data)
 	return nil
 }
 

internal/integration/server/server.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"net/http/httptest"
 
+	"github.com/99designs/gqlgen/graphql"
 	"github.com/99designs/gqlgen/graphql/handler"
 	"github.com/99designs/gqlgen/graphql/handler/transport"
 )
@@ -131,6 +132,10 @@ func (r *queryResolver) Fail(ctx context.Context) (*bool, error) {
 func RunServer() *httptest.Server {
 	gqlgenServer := handler.New(NewExecutableSchema(Config{Resolvers: &resolver{}}))
 	gqlgenServer.AddTransport(transport.POST{})
+	gqlgenServer.AroundResponses(func(ctx context.Context, next graphql.ResponseHandler) *graphql.Response {
+		graphql.RegisterExtension(ctx, "foobar", "test")
+		return next(ctx)
+	})
 	return httptest.NewServer(gqlgenServer)
 }