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| Greet people from the command line | 1 | //! Greetings. |
| 2 | ||
| Extract argument parsing into parse_args in lib.rs | 3 | /// Parsed command-line options. |
| 4 | #[derive(Debug, Default, PartialEq, Eq)] | |
| 5 | pub struct Options { | |
| 6 | /// The name to greet, if one was given. | |
| 7 | pub name: Option<String>, | |
| 8 | } | |
| 9 | ||
| 10 | /// Parses command-line arguments (excluding the program name). | |
| 11 | /// | |
| 12 | /// Arguments starting with `--` are treated as flags and skipped; the name is | |
| 13 | /// the first remaining argument. | |
| 14 | pub fn parse_args<I: IntoIterator<Item = String>>(args: I) -> Options { | |
| 15 | let name = args.into_iter().find(|arg| !arg.starts_with("--")); | |
| 16 | Options { name } | |
| 17 | } | |
| 18 | ||
| Greet people from the command line | 19 | /// The greeting for `name`. |
| 20 | pub fn greeting(name: &str) -> String { | |
| Handle empty and whitespace-only names, trim whitespace from input | 21 | let trimmed = name.trim(); |
| 22 | let display_name = if trimmed.is_empty() { "world" } else { trimmed }; | |
| 23 | format!("Hello, {display_name}!") | |
| Greet people from the command line | 24 | } |
| 25 | ||
| Add farewell function alongside greeting | 26 | /// The farewell for `name`. |
| 27 | pub fn farewell(name: &str) -> String { | |
| 28 | let trimmed = name.trim(); | |
| 29 | let display_name = if trimmed.is_empty() { "world" } else { trimmed }; | |
| 30 | format!("Goodbye, {display_name}!") | |
| 31 | } | |
| 32 | ||
| Greet people from the command line | 33 | #[cfg(test)] |
| 34 | mod tests { | |
| 35 | use super::*; | |
| 36 | ||
| Extract argument parsing into parse_args in lib.rs | 37 | fn args(list: &[&str]) -> Vec<String> { |
| 38 | list.iter().map(|s| s.to_string()).collect() | |
| 39 | } | |
| 40 | ||
| 41 | #[test] | |
| 42 | fn parse_args_no_args() { | |
| 43 | assert_eq!(parse_args(args(&[])).name, None); | |
| 44 | } | |
| 45 | ||
| 46 | #[test] | |
| 47 | fn parse_args_name() { | |
| 48 | assert_eq!(parse_args(args(&["Ada"])).name.as_deref(), Some("Ada")); | |
| 49 | } | |
| 50 | ||
| 51 | #[test] | |
| 52 | fn parse_args_skips_leading_flag() { | |
| 53 | assert_eq!( | |
| 54 | parse_args(args(&["--unknown", "Ada"])).name.as_deref(), | |
| 55 | Some("Ada") | |
| 56 | ); | |
| 57 | } | |
| 58 | ||
| Greet people from the command line | 59 | #[test] |
| 60 | fn greets_by_name() { | |
| 61 | assert_eq!(greeting("Ada"), "Hello, Ada!"); | |
| 62 | } | |
| Handle empty and whitespace-only names, trim whitespace from input | 63 | |
| 64 | #[test] | |
| 65 | fn greets_world_with_empty_string() { | |
| 66 | assert_eq!(greeting(""), "Hello, world!"); | |
| 67 | } | |
| 68 | ||
| 69 | #[test] | |
| 70 | fn greets_world_with_whitespace_only() { | |
| 71 | assert_eq!(greeting(" "), "Hello, world!"); | |
| 72 | } | |
| 73 | ||
| 74 | #[test] | |
| 75 | fn trims_whitespace_from_name() { | |
| 76 | assert_eq!(greeting(" Ada "), "Hello, Ada!"); | |
| 77 | } | |
| Add farewell function alongside greeting | 78 | |
| 79 | #[test] | |
| 80 | fn says_goodbye_by_name() { | |
| 81 | assert_eq!(farewell("Ada"), "Goodbye, Ada!"); | |
| 82 | } | |
| 83 | ||
| 84 | #[test] | |
| 85 | fn says_goodbye_to_world_when_blank() { | |
| 86 | assert_eq!(farewell(" "), "Goodbye, world!"); | |
| 87 | } | |
| 88 | ||
| 89 | #[test] | |
| 90 | fn farewell_trims_whitespace() { | |
| 91 | assert_eq!(farewell(" Ada "), "Goodbye, Ada!"); | |
| 92 | } | |
| Greet people from the command line | 93 | } |