add subcommands to usage string

1 files changed, 37 insertions, 0 deletions

diff --git a/example_test.go b/example_test.go
index 72807a7..eb8d315 100644
--- a/example_test.go
+++ b/example_test.go
@@ -135,3 +135,40 @@ func Example_usageString() {
 	//                          optimization level
 	//   --help, -h             display this help and exit
 }
+
+// This example shows the usage string generated by go-arg
+func Example_usageStringWithSubcommand() {
+	// These are the args you would pass in on the command line
+	os.Args = split("./example --help")
+
+	type getCmd struct {
+		Item string `arg:"positional" help:"item to fetch"`
+	}
+
+	type listCmd struct {
+		Format string `help:"output format"`
+		Limit  int
+	}
+
+	var args struct {
+		Verbose bool
+		Get     *getCmd  `arg:"subcommand" help:"fetch an item and print it"`
+		List    *listCmd `arg:"subcommand" help:"list available items"`
+	}
+
+	// This is only necessary when running inside golang's runnable example harness
+	osExit = func(int) {}
+
+	MustParse(&args)
+
+	// output:
+	// Usage: example [--verbose]
+	//
+	// Options:
+	//   --verbose
+	//   --help, -h             display this help and exit
+	//
+	// Commands:
+	//   get                    fetch an item and print it
+	//   list                   list available items
+}