gazelle?

main.go

@@ -56,5 +56,5 @@ func (r *cmdRootFS) Execute(args []string) error {
 		return err
 	}
 	defer out.Close()
-	return rootfs.Rootfs(in, out)
+	return rootfs.RootFS(in, out)
 }

rootfs/BUILD

@@ -1,13 +1,16 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_library")
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
 
 go_library(
     name = "rootfs_lib",
-    srcs = [
-        "rootfs.go",
-        "rootfs_tests.go",
-    ],
+    srcs = ["rootfs.go"],
     importpath = "github.com/motiejus/code/undocker/rootfs",
     visibility = ["//visibility:public"],
+)
+
+go_test(
+    name = "rootfs_test",
+    srcs = ["rootfs_test.go"],
+    embed = [":rootfs"],
     deps = [
         "@com_github_stretchr_testify//assert",
         "@com_github_stretchr_testify//require",

rootfs/rootfs_test.go

@@ -123,6 +123,8 @@ func TestRootFS(t *testing.T) {
 		},
 	}
 
+	assert.Fail(t, "foo")
+
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			in := bytes.NewReader(tt.image.bytes())