Test parse_args()

Author: theory

src/main.rs

@@ -31,6 +31,8 @@ struct Args {
     file: String,
 }
 
+const META_FILE: &str = "META.json";
+
 fn parse_args<I>(out: &mut impl Write, args: I) -> Result<Args, Box<dyn Error>>
 where
     I: IntoIterator,
@@ -39,7 +41,7 @@ where
     use lexopt::prelude::*;
     let mut res = Args {
         exit: false,
-        file: String::from("META.json"),
+        file: String::from(META_FILE),
     };
     let mut parser = lexopt::Parser::from_iter(args);
 
@@ -101,3 +103,106 @@ fn docs(out: &mut impl Write) -> Result<(), Box<dyn Error>> {
     writeln!(out, "Docs")?;
     Ok(())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use core::panic;
+    use std::str;
+
+    struct TC<'a> {
+        name: &'a str,
+        args: &'a [&'a str],
+        exit: bool,
+        file: &'a str,
+        out: &'a str,
+    }
+
+    #[test]
+    fn test_parse_args() -> Result<(), Box<dyn Error>> {
+        for tc in [
+            TC {
+                name: "no args",
+                args: &["meta"],
+                exit: false,
+                file: META_FILE,
+                out: "",
+            },
+            TC {
+                name: "short help",
+                args: &["meta", "-h"],
+                exit: true,
+                file: META_FILE,
+                out: "Usage: meta [--help | h] [--version | -v] [<path>]\n\n\
+                    Options:\n\
+                    \x20 -h --help     Print this usage statement and exit\n\
+                    \x20 -v --version  Print the version number and exit\n",
+            },
+            TC {
+                name: "long help",
+                args: &["meta", "--help"],
+                exit: true,
+                file: META_FILE,
+                out: "Usage: meta [--help | h] [--version | -v] [<path>]\n\n\
+                    Options:\n\
+                    \x20 -h --help     Print this usage statement and exit\n\
+                    \x20 -v --version  Print the version number and exit\n",
+            },
+            TC {
+                name: "short version",
+                args: &["meta", "-v"],
+                exit: true,
+                file: META_FILE,
+                out: concat!("meta ", env!("CARGO_PKG_VERSION"), "\n"),
+            },
+            TC {
+                name: "long version",
+                args: &["meta", "--version"],
+                exit: true,
+                file: META_FILE,
+                out: concat!("meta ", env!("CARGO_PKG_VERSION"), "\n"),
+            },
+            TC {
+                name: "short man",
+                args: &["meta", "-m"],
+                exit: true,
+                file: META_FILE,
+                out: "Docs\n",
+            },
+            TC {
+                name: "long man",
+                args: &["meta", "--man"],
+                exit: true,
+                file: META_FILE,
+                out: "Docs\n",
+            },
+            TC {
+                name: "file name",
+                args: &["meta", "hello.json"],
+                exit: false,
+                file: "hello.json",
+                out: "",
+            },
+        ] {
+            let mut file: Vec<u8> = Vec::new();
+            match parse_args(&mut file, tc.args) {
+                Err(e) => panic!("test {} failed: {e}", tc.name),
+                Ok(res) => {
+                    assert_eq!(res.exit, tc.exit);
+                    assert_eq!(res.file, tc.file);
+                    assert_eq!(str::from_utf8(&file)?, tc.out);
+                }
+            }
+        }
+
+        let mut file: Vec<u8> = Vec::new();
+        match parse_args(&mut file, ["hi", "-x"]) {
+            Ok(_) => panic!("Should have failed on -x but did not"),
+            Err(e) => {
+                assert_eq!(e.to_string(), "invalid option '-x'");
+            }
+        }
+
+        Ok(())
+    }
+}