| 1 | //! Greetings. |
| 2 | |
| 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 | |
| 19 | /// The greeting for `name`. |
| 20 | pub fn greeting(name: &str) -> String { |
| 21 | let trimmed = name.trim(); |
| 22 | let display_name = if trimmed.is_empty() { "world" } else { trimmed }; |
| 23 | format!("Hello, {display_name}!") |
| 24 | } |
| 25 | |
| 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 | |
| 33 | #[cfg(test)] |
| 34 | mod tests { |
| 35 | use super::*; |
| 36 | |
| 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 | |
| 59 | #[test] |
| 60 | fn greets_by_name() { |
| 61 | assert_eq!(greeting("Ada"), "Hello, Ada!"); |
| 62 | } |
| 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 | } |
| 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 | } |
| 93 | } |