Update should accept empty path with version

internal/cmdupdate/cmdupdate_test.go

@@ -229,6 +229,55 @@ func TestCmd_successNoGit(t *testing.T) {
 	}
 }
 
+func TestCmd_onlyVersionAsInput(t *testing.T) {
+	g, w, clean := testutil.SetupRepoAndWorkspace(t, testutil.Content{
+		Data:   testutil.Dataset1,
+		Branch: "master",
+	})
+	defer clean()
+
+	err := os.RemoveAll(".git")
+	if !assert.NoError(t, err) {
+		t.FailNow()
+	}
+	dest := filepath.Join(w.WorkspaceDirectory, g.RepoName)
+
+	// clone the repo
+	getCmd := cmdget.NewRunner(fake.CtxWithDefaultPrinter(), "kpt")
+	getCmd.Command.SetArgs([]string{"file://" + g.RepoDirectory + ".git", w.WorkspaceDirectory})
+	err = getCmd.Command.Execute()
+	if !assert.NoError(t, err) {
+		return
+	}
+	if !g.AssertEqual(t, filepath.Join(g.DatasetDirectory, testutil.Dataset1), dest, true) {
+		return
+	}
+
+	// update the master branch
+	if !assert.NoError(t, g.ReplaceData(testutil.Dataset2)) {
+		return
+	}
+
+	// commit the upstream but not the local
+	_, err = g.Commit("new dataset")
+	if !assert.NoError(t, err) {
+		return
+	}
+
+	// update the cloned package
+	updateCmd := cmdupdate.NewRunner(fake.CtxWithDefaultPrinter(), "kpt")
+	defer testutil.Chdir(t, dest)()
+	updateCmd.Command.SetArgs([]string{"@master"})
+	err = updateCmd.Command.Execute()
+	if !assert.NoError(t, err) {
+		t.FailNow()
+	}
+
+	if !g.AssertEqual(t, filepath.Join(g.DatasetDirectory, testutil.Dataset2), dest, true) {
+		return
+	}
+}
+
 // NoOpRunE is a noop function to replace the run function of a command.  Useful for testing argument parsing.
 var NoOpRunE = func(cmd *cobra.Command, args []string) error { return nil }
 

internal/util/argutil/argutil.go

@@ -94,11 +94,13 @@ func ParseFieldPath(path string) ([]string, error) {
 func ResolveSymlink(ctx context.Context, path string) (string, error) {
 	isSymlink := false
 	f, err := os.Lstat(path)
-	if err != nil {
-		return "", err
-	}
-	if f.Mode().Type() == os.ModeSymlink {
-		isSymlink = true
+	if err == nil {
+		// this step only helps with printing WARN message by checking if the input
+		// path has symlink, so do not error out at this phase and let
+		// filepath.EvalSymlinks(path) handle the cases
+		if f.Mode().Type() == os.ModeSymlink {
+			isSymlink = true
+		}
 	}
 	rp, err := filepath.EvalSymlinks(path)
 	if err != nil {

internal/util/argutil/argutil_test.go

@@ -144,6 +144,10 @@ func TestResolveSymlink(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Equal(t, "foo", actual2)
 
+	actual3, err := ResolveSymlink(fake.CtxWithDefaultPrinter(), ".")
+	assert.NoError(t, err)
+	assert.Equal(t, "", actual3)
+
 	_, err = ResolveSymlink(fake.CtxWithDefaultPrinter(), "baz")
 	assert.Error(t, err)
 	assert.Equal(t, "lstat baz: no such file or directory", err.Error())