feat(graphql): normalise custom mount paths

Co-Authored-By: Virgil <virgil@lethean.io>

graphql.go

@@ -4,6 +4,7 @@ package api
 
 import (
 	"net/http"
+	"strings"
 
 	"github.com/99designs/gqlgen/graphql"
 	"github.com/99designs/gqlgen/graphql/handler"
@@ -35,7 +36,7 @@ func WithPlayground() GraphQLOption {
 // The default path is "/graphql".
 func WithGraphQLPath(path string) GraphQLOption {
 	return func(cfg *graphqlConfig) {
-		cfg.path = path
+		cfg.path = normaliseGraphQLPath(path)
 	}
 }
 
@@ -55,6 +56,22 @@ func mountGraphQL(r *gin.Engine, cfg *graphqlConfig) {
 	}
 }
 
+// normaliseGraphQLPath coerces custom GraphQL paths into a stable form.
+// The path always begins with a single slash and never ends with one.
+func normaliseGraphQLPath(path string) string {
+	path = strings.TrimSpace(path)
+	if path == "" {
+		return defaultGraphQLPath
+	}
+
+	path = "/" + strings.Trim(path, "/")
+	if path == "/" {
+		return defaultGraphQLPath
+	}
+
+	return path
+}
+
 // wrapHTTPHandler adapts a standard http.Handler to a Gin handler function.
 func wrapHTTPHandler(h http.Handler) gin.HandlerFunc {
 	return func(c *gin.Context) {

graphql_test.go

@@ -192,6 +192,72 @@ func TestWithGraphQL_Good_CustomPath(t *testing.T) {
 	}
 }
 
+func TestWithGraphQL_Good_NormalisesCustomPath(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+
+	e, err := api.New(api.WithGraphQL(newTestSchema(), api.WithGraphQLPath(" /gql/ "), api.WithPlayground()))
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	srv := httptest.NewServer(e.Handler())
+	defer srv.Close()
+
+	body := `{"query":"{ name }"}`
+	resp, err := http.Post(srv.URL+"/gql", "application/json", strings.NewReader(body))
+	if err != nil {
+		t.Fatalf("request failed: %v", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		t.Fatalf("expected 200 at normalised /gql, got %d", resp.StatusCode)
+	}
+
+	pgResp, err := http.Get(srv.URL + "/gql/playground")
+	if err != nil {
+		t.Fatalf("playground request failed: %v", err)
+	}
+	defer pgResp.Body.Close()
+
+	if pgResp.StatusCode != http.StatusOK {
+		t.Fatalf("expected 200 at normalised /gql/playground, got %d", pgResp.StatusCode)
+	}
+}
+
+func TestWithGraphQL_Good_DefaultPathWhenEmptyCustomPath(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+
+	e, err := api.New(api.WithGraphQL(newTestSchema(), api.WithGraphQLPath(""), api.WithPlayground()))
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	srv := httptest.NewServer(e.Handler())
+	defer srv.Close()
+
+	body := `{"query":"{ name }"}`
+	resp, err := http.Post(srv.URL+"/graphql", "application/json", strings.NewReader(body))
+	if err != nil {
+		t.Fatalf("request failed: %v", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		t.Fatalf("expected 200 at default /graphql, got %d", resp.StatusCode)
+	}
+
+	pgResp, err := http.Get(srv.URL + "/graphql/playground")
+	if err != nil {
+		t.Fatalf("playground request failed: %v", err)
+	}
+	defer pgResp.Body.Close()
+
+	if pgResp.StatusCode != http.StatusOK {
+		t.Fatalf("expected 200 at default /graphql/playground, got %d", pgResp.StatusCode)
+	}
+}
+
 func TestWithGraphQL_Good_CombinesWithOtherMiddleware(t *testing.T) {
 	gin.SetMode(gin.TestMode)