add tree

internal/tree/BUILD

@@ -0,0 +1,15 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["tree.go"],
+    importpath = "github.com/motiejus/code/undocker/internal/tree",
+    visibility = ["//src:__subpackages__"],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["tree_test.go"],
+    embed = [":go_default_library"],
+    deps = ["@com_github_stretchr_testify//assert:go_default_library"],
+)