diff --git a/frontend/dockerfile/dockerfile_namedcontext_test.go b/frontend/dockerfile/dockerfile_namedcontext_test.go
index 168ce8ddbf7fe..690d60fb5b6a9 100644
--- a/frontend/dockerfile/dockerfile_namedcontext_test.go
+++ b/frontend/dockerfile/dockerfile_namedcontext_test.go
@@ -1,13 +1,16 @@
 package dockerfile
 
 import (
+	"math"
 	"testing"
 
 	"github.com/containerd/continuity/fs/fstest"
 	"github.com/moby/buildkit/client"
 	"github.com/moby/buildkit/frontend/dockerui"
 	"github.com/moby/buildkit/util/testutil/integration"
+	"github.com/pkg/errors"
 	"github.com/stretchr/testify/require"
+	"golang.org/x/sync/errgroup"
 )
 
 func testNamedFilteredContext(t *testing.T, sb integration.Sandbox) {
@@ -41,32 +44,65 @@ COPY --link --from=d /bar /foo.d
 
 	dir := integration.Tmpdir(
 		t,
-		fstest.CreateFile("Dockerfile", dockerfile, 0600),
+		fstest.CreateFile(dockerui.DefaultDockerfileName, dockerfile, 0600),
 	)
 
-	dir2 := integration.Tmpdir(t)
+	dir2 := integration.Tmpdir(t,
+		// small file
+		fstest.CreateFile("foo", []byte(`foo`), 0600),
+		// blank file that's just large
+		fstest.CreateFile("bar", make([]byte, 4096*1000), 0600),
+	)
 
 	f := getFrontend(t, sb)
 
-	runTest := func(t *testing.T, target string, maxTransfer float64) {
+	runTest := func(t *testing.T, target string, min, max int64) {
 		t.Run(target, func(t *testing.T) {
-			_, err := f.Solve(ctx, c, client.SolveOpt{
-				FrontendAttrs: map[string]string{
-					"context:a": "local:a",
-					"target":    target,
-				},
-				LocalDirs: map[string]string{
-					dockerui.DefaultDockerfileName:   dir,
-					dockerui.DefaultLocalNameContext: dir,
-					"a":                              dir2,
-				},
-			}, nil)
+			ch := make(chan *client.SolveStatus)
+
+			eg, ctx := errgroup.WithContext(sb.Context())
+			eg.Go(func() error {
+				_, err := f.Solve(ctx, c, client.SolveOpt{
+					FrontendAttrs: map[string]string{
+						"context:a": "local:a",
+						"target":    target,
+					},
+					LocalDirs: map[string]string{
+						dockerui.DefaultLocalNameDockerfile: dir,
+						dockerui.DefaultLocalNameContext:    dir,
+						"a":                                 dir2,
+					},
+				}, ch)
+				return err
+			})
+
+			eg.Go(func() error {
+				var transferred int64
+				for ss := range ch {
+					for _, status := range ss.Statuses {
+						if status.Name != "transferring" && status.Completed == nil {
+							continue
+						}
+						transferred += status.Current
+					}
+				}
+
+				t.Logf("transferred %d bytes", transferred)
+				if transferred < min {
+					return errors.Errorf("not enough data was transferred, %d < %d", transferred, min)
+				} else if transferred > max {
+					return errors.Errorf("too much data was transferred, %d > %d", transferred, max)
+				}
+				return nil
+			})
+
+			err := eg.Wait()
 			require.NoError(t, err)
 		})
 	}
 
-	runTest(t, "run_mount", 0)
-	runTest(t, "copy_from", 0)
-	runTest(t, "image_source", 0)
-	runTest(t, "all", 0)
+	runTest(t, "run_mount", 1, 1024)
+	runTest(t, "copy_from", 1, 1024)
+	runTest(t, "image_source", 4096*1000, math.MaxInt64)
+	runTest(t, "all", 4096*1000, math.MaxInt64)
 }