Implements Operation RoundTripper (#9)

* Adds stretchr/testify

* Implements operation roundtrip

* Fixes go.mod

* Improves http/operation_test.go

* Improves test coverage

* Improves handling when operation is not provided

* Calls Close on copyBody after read

go.mod

@@ -6,4 +6,9 @@ require (
 	github.com/matryer/is v1.4.0
 	github.com/mitchellh/mapstructure v1.4.2
 	github.com/pkg/errors v0.9.1
+	github.com/stretchr/testify v1.7.5
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/stretchr/objx v0.4.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -1,6 +1,21 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/matryer/is v1.4.0 h1:sosSmIWwkYITGrxZ25ULNDeKiMNzFSr4V/eqBQP0PeE=
 github.com/matryer/is v1.4.0/go.mod h1:8I/i5uYgLzgsgEloJE1U6xx5HkBQpAZvepWuujKwMRU=
 github.com/mitchellh/mapstructure v1.4.2 h1:6h7AQ0yhTcIsmFmnAwQls75jp2Gzs4iB8W7pjMO+rqo=
 github.com/mitchellh/mapstructure v1.4.2/go.mod h1:bFUtVrKA4DC2yAKiSyO/QUcy7e+RRV2QTWOzhPopBRo=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.4.0 h1:M2gUjqZET1qApGOWNSnZ49BAIMX4F/1plDv3+l31EJ4=
+github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.7.5 h1:s5PTfem8p8EbKQOctVV53k6jCJt3UX4IEJzwh+C324Q=
+github.com/stretchr/testify v1.7.5/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

http/operation.go

@@ -0,0 +1,54 @@
+package http
+
+import (
+	"io"
+	"net/http"
+	"regexp"
+)
+
+type addOperation struct {
+	inner http.RoundTripper
+}
+
+const operationRegex = `((?:query\s)|(?:mutation\s))(\w+)`
+
+func SetGraphqlOperation(inner http.RoundTripper) http.RoundTripper {
+	return &addOperation{
+		inner: inner,
+	}
+}
+
+func (ug *addOperation) RoundTrip(r *http.Request) (*http.Response, error) {
+	values := r.URL.Query()
+	operation := getOperationName(r)
+
+	if operation != "" {
+		values.Add("operation", operation)
+		r.URL.RawQuery = values.Encode()
+	}
+
+	return ug.inner.RoundTrip(r)
+}
+
+func getOperationName(r *http.Request) string {
+	regex := regexp.MustCompile(operationRegex)
+	getBody := r.GetBody
+
+	copyBody, err := getBody()
+	if err != nil {
+		return ""
+	}
+
+	b, err := io.ReadAll(copyBody)
+	if err != nil {
+		return ""
+	}
+	copyBody.Close()
+
+	operation := regex.FindAllSubmatch(b, -1)
+	if operation != nil {
+		return string(operation[0][2])
+	}
+
+	return ""
+}

http/operation_test.go

@@ -0,0 +1,101 @@
+package http
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	graphql "github.com/sumup/graphql"
+)
+
+func Test_SetGraphqlOperation(t *testing.T) {
+	t.Run("SetGraphqlOperation with query", func(t *testing.T) {
+		handlerFunc := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			assert.Equal(t, r.URL.RawQuery, "operation=FooBar")
+
+			_, _ = io.WriteString(w, "{}")
+		})
+
+		runner := func(t *testing.T, client *graphql.Client) {
+			ctx := context.Background()
+			req := graphql.NewRequest("query FooBar {}")
+			var resp struct{}
+
+			err := client.Run(ctx, req, &resp)
+			assert.NoError(t, err)
+		}
+
+		runTest(t, handlerFunc, runner)
+	})
+
+	t.Run("SetGraphqlOperation with mutation", func(t *testing.T) {
+		handlerFunc := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			assert.Equal(t, r.URL.RawQuery, "operation=FooBar")
+
+			_, _ = io.WriteString(w, `{
+				"data": {
+		        "fooBar": {
+		            "messages": [],
+		            "result": null,
+		            "successful": false
+		        }
+		    }
+			}`)
+		})
+
+		runner := func(t *testing.T, client *graphql.Client) {
+			ctx := context.Background()
+			req := graphql.NewMutation(`
+				mutation FooBar {
+					fooBar {
+				    successful
+				    messages
+				    result
+					}
+				}
+			`)
+			var resp struct{}
+
+			err := client.Run(ctx, req, &resp)
+			assert.NoError(t, err)
+		}
+
+		runTest(t, handlerFunc, runner)
+	})
+
+	t.Run("SetGraphqlOperation when operation name is not provided", func(t *testing.T) {
+		handlerFunc := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			assert.Empty(t, r.URL.RawQuery)
+
+			_, _ = io.WriteString(w, "{}")
+		})
+
+		runner := func(t *testing.T, client *graphql.Client) {
+			ctx := context.Background()
+			req := graphql.NewRequest("query {}")
+			var resp struct{}
+
+			err := client.Run(ctx, req, &resp)
+			assert.NoError(t, err)
+		}
+
+		runTest(t, handlerFunc, runner)
+	})
+}
+
+func runTest(t *testing.T, handlerFunc http.HandlerFunc, runner func(*testing.T, *graphql.Client)) {
+	srv := httptest.NewServer(handlerFunc)
+	defer srv.Close()
+
+	transport := http.DefaultTransport
+	transport = SetGraphqlOperation(transport)
+	httpClient := &http.Client{Transport: transport}
+
+	client := graphql.NewClient(srv.URL, graphql.WithHTTPClient(httpClient))
+
+	runner(t, client)
+}