Add tests for parsing prereleases

src/error.rs

@@ -1,6 +1,6 @@
 use std::{fmt, num::TryFromIntError};
 
-#[derive(Debug)]
+#[derive(Debug, PartialEq)]
 pub enum Error {
     FromUint,
     ParsePreRelease,

src/prerelease.rs

@@ -164,3 +164,47 @@ impl PartialOrd for PreRelease {
         Some(a.cmp(&b))
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parse_alpha() {
+        let alpha: PreRelease = "alpha".parse().unwrap();
+        let alpha1: PreRelease = "Alpha1".parse().unwrap();
+        let alpha2: PreRelease = "alpha2".parse().unwrap();
+        let one = NonZeroU16::new(1).unwrap();
+        let two = NonZeroU16::new(2).unwrap();
+        assert_eq!(alpha, PreRelease::Alpha(None));
+        assert_eq!(alpha1, PreRelease::Alpha(Some(one)));
+        assert_eq!(alpha2, PreRelease::Alpha(Some(two)));
+    }
+
+    #[test]
+    fn parse_beta() {
+        assert_eq!(
+            "beta".parse::<PreRelease>().unwrap(),
+            PreRelease::Beta(None),
+        );
+        assert_eq!(
+            "beta1".parse::<PreRelease>().unwrap(),
+            PreRelease::Beta(Some(NonZeroU16::new(1).unwrap()))
+        );
+        assert_eq!(
+            "Beta2".parse::<PreRelease>().unwrap(),
+            PreRelease::Beta(Some(NonZeroU16::new(2).unwrap()))
+        );
+        assert_eq!("Beta2a".parse::<PreRelease>(), Err(Error::ParsePreRelease));
+    }
+
+    #[test]
+    fn parse_rc() {
+        assert_eq!(
+            "rc3".parse::<PreRelease>().unwrap(),
+            PreRelease::RC(Some(NonZeroU16::new(3).unwrap()))
+        );
+        assert_eq!("Rc".parse::<PreRelease>().unwrap(), PreRelease::RC(None));
+        assert_eq!("RC".parse::<PreRelease>().unwrap(), PreRelease::RC(None));
+    }
+}