feat: Add the WithUsage function.

This commit is contained in:
Florian Forster 2024-01-12 08:49:07 +01:00
parent 4fb0a66a34
commit 4cba342aae
2 changed files with 37 additions and 0 deletions

13
args.go
View file

@ -129,3 +129,16 @@ func MatchAll(pargs ...PositionalArgs) PositionalArgs {
func ExactValidArgs(n int) PositionalArgs { func ExactValidArgs(n int) PositionalArgs {
return MatchAll(ExactArgs(n), OnlyValidArgs) return MatchAll(ExactArgs(n), OnlyValidArgs)
} }
// WithUsage wraps another PositionalArgs function. If the function fails
// (returns a non-nil error), the error is supplemented with the command's
// usage message, providing the user with the information required to run the
// command correctly.
func WithUsage(wrapped PositionalArgs) PositionalArgs {
return func(cmd *Command, args []string) error {
if err := wrapped(cmd, args); err != nil {
return fmt.Errorf("%w\n\n%s", err, cmd.UsageString())
}
return nil
}
}

View file

@ -539,3 +539,27 @@ func TestLegacyArgsSubcmdAcceptsArgs(t *testing.T) {
t.Fatalf("Unexpected error: %v", err) t.Fatalf("Unexpected error: %v", err)
} }
} }
// WithUsage
func TestWithUsage(t *testing.T) {
c := getCommand(WithUsage(ExactArgs(1)), false)
_, err := executeCommand(c /* no args */)
if err == nil {
t.Fatalf("Expected error, got nil")
}
got, want := err.Error(), c.UsageString()
if !strings.Contains(got, want) {
t.Errorf("Expected error containing %q, got %q", want, got)
}
}
func ExampleWithUsage() {
cmd := &Command{
Use: "example <arg>",
Args: WithUsage(ExactArgs(1)),
}
_ = cmd // ignore unused
}