Complete unit testing

src/lib.rs

@@ -28,7 +28,7 @@ pub trait IMbid {
     fn mbid(&self) -> &str;
 }
 
-#[derive(Debug, PartialEq, Eq)]
+#[derive(Debug)]
 enum UrlType {
     MusicBrainz,
     MusicButler,
@@ -36,12 +36,17 @@ enum UrlType {
     Qobuz,
 }
 
-#[derive(Debug, PartialEq, Eq)]
 struct InvalidUrlError {
     url_type: UrlType,
     url: String,
 }
 
+impl fmt::Display for InvalidUrlError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "invalid url of type {:?}: {}", self.url_type, self.url)
+    }
+}
+
 /// MusicBrainz reference.
 #[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Eq)]
 pub struct MusicBrainz(Url);
@@ -422,7 +427,7 @@ impl From<uuid::Error> for Error {
 
 impl From<InvalidUrlError> for Error {
     fn from(err: InvalidUrlError) -> Error {
-        Error::InvalidUrlError(format!("{:?} - {}", err.url_type, err.url))
+        Error::InvalidUrlError(err.to_string())
     }
 }
 
@@ -620,11 +625,27 @@ mod tests {
         assert_eq!(url, mb.url());
         assert_eq!(uuid, mb.mbid());
 
+        let url = format!("not a url at all");
+        let expected_error: Error = url::ParseError::RelativeUrlWithoutBase.into();
+        let actual_error = MusicBrainz::new(&url).unwrap_err();
+        assert_eq!(actual_error, expected_error);
+        assert_eq!(actual_error.to_string(), expected_error.to_string());
+
         let url = format!("https://musicbrainz.org/artist/i-am-not-a-uuid");
-        assert!(MusicBrainz::new(&url).is_err());
+        let expected_error: Error = Uuid::try_parse("i-am-not-a-uuid").unwrap_err().into();
+        let actual_error = MusicBrainz::new(&url).unwrap_err();
+        assert_eq!(actual_error, expected_error);
+        assert_eq!(actual_error.to_string(), expected_error.to_string());
 
         let url = format!("https://musicbrainz.org/artist");
-        assert!(MusicBrainz::new(&url).is_err());
+        let expected_error: Error = InvalidUrlError {
+            url_type: UrlType::MusicBrainz,
+            url: url.clone(),
+        }
+        .into();
+        let actual_error = MusicBrainz::new(&url).unwrap_err();
+        assert_eq!(actual_error, expected_error);
+        assert_eq!(actual_error.to_string(), expected_error.to_string());
     }
 
     #[test]