| 1 | //! Greetings. |
| 2 | |
| 3 | /// Parsed command-line options. |
| 4 | #[derive(Debug, PartialEq, Eq)] |
| 5 | pub struct Options { |
| 6 | /// The name to greet, if one was given. |
| 7 | pub name: Option<String>, |
| 8 | /// Whether to upper-case the greeting (`--shout`). |
| 9 | pub shout: bool, |
| 10 | /// Whether to print the crate version and exit (`--version`). |
| 11 | pub version: bool, |
| 12 | /// How many times to print the greeting (`--times N`). |
| 13 | pub times: usize, |
| 14 | } |
| 15 | |
| 16 | impl Default for Options { |
| 17 | fn default() -> Self { |
| 18 | Options { |
| 19 | name: None, |
| 20 | shout: false, |
| 21 | version: false, |
| 22 | times: 1, |
| 23 | } |
| 24 | } |
| 25 | } |
| 26 | |
| 27 | /// Parses command-line arguments (excluding the program name). |
| 28 | /// |
| 29 | /// `--shout` sets [`Options::shout`], `--version` sets |
| 30 | /// [`Options::version`], and `--times N` sets [`Options::times`] (the |
| 31 | /// next argument is consumed as the value); other arguments starting |
| 32 | /// with `--` are treated as flags and skipped. The name is the first |
| 33 | /// remaining argument. |
| 34 | /// |
| 35 | /// Returns an error message if `--times` has a missing or non-numeric value. |
| 36 | pub fn parse_args<I: IntoIterator<Item = String>>(args: I) -> Result<Options, String> { |
| 37 | let mut options = Options::default(); |
| 38 | let mut args = args.into_iter(); |
| 39 | while let Some(arg) = args.next() { |
| 40 | if arg == "--shout" { |
| 41 | options.shout = true; |
| 42 | } else if arg == "--version" { |
| 43 | options.version = true; |
| 44 | } else if arg == "--times" { |
| 45 | let value = args |
| 46 | .next() |
| 47 | .ok_or_else(|| "--times requires a value".to_owned())?; |
| 48 | options.times = value |
| 49 | .parse() |
| 50 | .map_err(|_| format!("--times value must be a number, got {value:?}"))?; |
| 51 | } else if !arg.starts_with("--") && options.name.is_none() { |
| 52 | options.name = Some(arg); |
| 53 | } |
| 54 | } |
| 55 | Ok(options) |
| 56 | } |
| 57 | |
| 58 | /// `text` upper-cased. |
| 59 | pub fn shout(text: &str) -> String { |
| 60 | text.to_uppercase() |
| 61 | } |
| 62 | |
| 63 | /// The greeting for `name`. |
| 64 | pub fn greeting(name: &str) -> String { |
| 65 | let trimmed = name.trim(); |
| 66 | let display_name = if trimmed.is_empty() { "world" } else { trimmed }; |
| 67 | format!("Hello, {display_name}!") |
| 68 | } |
| 69 | |
| 70 | /// The farewell for `name`. |
| 71 | pub fn farewell(name: &str) -> String { |
| 72 | let trimmed = name.trim(); |
| 73 | let display_name = if trimmed.is_empty() { "world" } else { trimmed }; |
| 74 | format!("Goodbye, {display_name}!") |
| 75 | } |
| 76 | |
| 77 | #[cfg(test)] |
| 78 | mod tests { |
| 79 | use super::*; |
| 80 | |
| 81 | fn args(list: &[&str]) -> Vec<String> { |
| 82 | list.iter().map(|s| s.to_string()).collect() |
| 83 | } |
| 84 | |
| 85 | #[test] |
| 86 | fn parse_args_no_args() { |
| 87 | assert_eq!(parse_args(args(&[])).unwrap().name, None); |
| 88 | } |
| 89 | |
| 90 | #[test] |
| 91 | fn parse_args_name() { |
| 92 | assert_eq!(parse_args(args(&["Ada"])).unwrap().name.as_deref(), Some("Ada")); |
| 93 | } |
| 94 | |
| 95 | #[test] |
| 96 | fn parse_args_skips_leading_flag() { |
| 97 | assert_eq!( |
| 98 | parse_args(args(&["--unknown", "Ada"])).unwrap().name.as_deref(), |
| 99 | Some("Ada") |
| 100 | ); |
| 101 | } |
| 102 | |
| 103 | #[test] |
| 104 | fn parse_args_shout_defaults_off() { |
| 105 | assert!(!parse_args(args(&["Ada"])).unwrap().shout); |
| 106 | } |
| 107 | |
| 108 | #[test] |
| 109 | fn parse_args_shout_before_name() { |
| 110 | let options = parse_args(args(&["--shout", "Ada"])).unwrap(); |
| 111 | assert!(options.shout); |
| 112 | assert_eq!(options.name.as_deref(), Some("Ada")); |
| 113 | } |
| 114 | |
| 115 | #[test] |
| 116 | fn parse_args_shout_after_name() { |
| 117 | let options = parse_args(args(&["Ada", "--shout"])).unwrap(); |
| 118 | assert!(options.shout); |
| 119 | assert_eq!(options.name.as_deref(), Some("Ada")); |
| 120 | } |
| 121 | |
| 122 | #[test] |
| 123 | fn parse_args_shout_alone() { |
| 124 | let options = parse_args(args(&["--shout"])).unwrap(); |
| 125 | assert!(options.shout); |
| 126 | assert_eq!(options.name, None); |
| 127 | } |
| 128 | |
| 129 | #[test] |
| 130 | fn parse_args_version_defaults_off() { |
| 131 | assert!(!parse_args(args(&["Ada"])).unwrap().version); |
| 132 | } |
| 133 | |
| 134 | #[test] |
| 135 | fn parse_args_version() { |
| 136 | let options = parse_args(args(&["--version"])).unwrap(); |
| 137 | assert!(options.version); |
| 138 | assert_eq!(options.name, None); |
| 139 | } |
| 140 | |
| 141 | #[test] |
| 142 | fn parse_args_times_defaults_to_one() { |
| 143 | assert_eq!(parse_args(args(&["Ada"])).unwrap().times, 1); |
| 144 | } |
| 145 | |
| 146 | #[test] |
| 147 | fn parse_args_times_valid() { |
| 148 | let options = parse_args(args(&["--times", "3", "Ada"])).unwrap(); |
| 149 | assert_eq!(options.times, 3); |
| 150 | assert_eq!(options.name.as_deref(), Some("Ada")); |
| 151 | } |
| 152 | |
| 153 | #[test] |
| 154 | fn parse_args_times_missing_value() { |
| 155 | assert!(parse_args(args(&["--times"])).is_err()); |
| 156 | } |
| 157 | |
| 158 | #[test] |
| 159 | fn parse_args_times_non_number() { |
| 160 | assert!(parse_args(args(&["--times", "abc", "Ada"])).is_err()); |
| 161 | } |
| 162 | |
| 163 | #[test] |
| 164 | fn shout_upper_cases_greeting() { |
| 165 | assert_eq!(shout(&greeting("Ada")), "HELLO, ADA!"); |
| 166 | } |
| 167 | |
| 168 | #[test] |
| 169 | fn greets_by_name() { |
| 170 | assert_eq!(greeting("Ada"), "Hello, Ada!"); |
| 171 | } |
| 172 | |
| 173 | #[test] |
| 174 | fn greets_world_with_empty_string() { |
| 175 | assert_eq!(greeting(""), "Hello, world!"); |
| 176 | } |
| 177 | |
| 178 | #[test] |
| 179 | fn greets_world_with_whitespace_only() { |
| 180 | assert_eq!(greeting(" "), "Hello, world!"); |
| 181 | } |
| 182 | |
| 183 | #[test] |
| 184 | fn trims_whitespace_from_name() { |
| 185 | assert_eq!(greeting(" Ada "), "Hello, Ada!"); |
| 186 | } |
| 187 | |
| 188 | #[test] |
| 189 | fn says_goodbye_by_name() { |
| 190 | assert_eq!(farewell("Ada"), "Goodbye, Ada!"); |
| 191 | } |
| 192 | |
| 193 | #[test] |
| 194 | fn says_goodbye_to_world_when_blank() { |
| 195 | assert_eq!(farewell(" "), "Goodbye, world!"); |
| 196 | } |
| 197 | |
| 198 | #[test] |
| 199 | fn farewell_trims_whitespace() { |
| 200 | assert_eq!(farewell(" Ada "), "Goodbye, Ada!"); |
| 201 | } |
| 202 | } |