Add reproducable test cases

codegen/testserver/generated_test.go

@@ -4,10 +4,13 @@
 package testserver
 
 import (
+	"context"
 	"net/http"
+	"net/http/httptest"
 	"reflect"
 	"testing"
 
+	"github.com/99designs/gqlgen/client"
 	"github.com/99designs/gqlgen/handler"
 	"github.com/stretchr/testify/require"
 )
@@ -30,3 +33,51 @@ func TestEnums(t *testing.T) {
 		require.Equal(t, StatusError, AllStatus[1])
 	})
 }
+
+func TestUnionFragments(t *testing.T) {
+	resolvers := &Stub{}
+	resolvers.QueryResolver.ShapeUnion = func(ctx context.Context) (ShapeUnion, error) {
+		return &Circle{Radius: 32}, nil
+	}
+
+	srv := httptest.NewServer(handler.GraphQL(NewExecutableSchema(Config{Resolvers: resolvers})))
+	c := client.New(srv.URL)
+
+	t.Run("inline fragment on union", func(t *testing.T) {
+		var resp struct {
+			ShapeUnion struct {
+				Radius float64
+			}
+		}
+		c.MustPost(`query {
+			shapeUnion {
+				... on Circle {
+					radius
+				}
+			}
+		}
+		`, &resp)
+		require.NotEmpty(t, resp.ShapeUnion.Radius)
+	})
+
+	t.Run("named fragment", func(t *testing.T) {
+		var resp struct {
+			ShapeUnion struct {
+				Radius float64
+			}
+		}
+		c.MustPost(`query {
+			shapeUnion {
+				...C
+			}
+		}
+
+		fragment C on ShapeUnion {
+			... on Circle {
+				radius
+			}
+		}
+		`, &resp)
+		require.NotEmpty(t, resp.ShapeUnion.Radius)
+	})
+}

codegen/testserver/resolver.go

@@ -95,6 +95,9 @@ func (r *queryResolver) DirectiveInput(ctx context.Context, arg InputDirectives)
 func (r *queryResolver) InputSlice(ctx context.Context, arg []string) (bool, error) {
 	panic("not implemented")
 }
+func (r *queryResolver) ShapeUnion(ctx context.Context) (ShapeUnion, error) {
+	panic("not implemented")
+}
 func (r *queryResolver) KeywordArgs(ctx context.Context, breakArg string, defaultArg string, funcArg string, interfaceArg string, selectArg string, caseArg string, deferArg string, goArg string, mapArg string, structArg string, chanArg string, elseArg string, gotoArg string, packageArg string, switchArg string, constArg string, fallthroughArg string, ifArg string, rangeArg string, typeArg string, continueArg string, forArg string, importArg string, returnArg string, varArg string) (bool, error) {
 	panic("not implemented")
 }

codegen/testserver/schema.graphql

@@ -17,6 +17,7 @@ type Query {
     directiveInputNullable(arg: InputDirectives): String
     directiveInput(arg: InputDirectives!): String
     inputSlice(arg: [String!]!): Boolean!
+    shapeUnion: ShapeUnion!
 }
 
 type Subscription {