Merge pull request #47 from Holzhaus/testing

Fix division by zero error when calculating string distance

src/distance/mod.rs

@@ -31,10 +31,10 @@ pub struct Distance(f64);
 
 impl Distance {
     /// Minimum distance (representing equality).
-    const MIN: Distance = Distance(0.0);
+    pub const MIN: Distance = Distance(0.0);
 
     /// Maximum distance.
-    const MAX: Distance = Distance(1.0);
+    pub const MAX: Distance = Distance(1.0);
 
     /// Return `true` if the distance is zero.
     pub const fn is_equality(&self) -> bool {

src/distance/string.rs

@@ -49,9 +49,16 @@ pub fn between(lhs: &str, rhs: &str) -> Distance {
     let lhs = normalize(lhs);
     let rhs = normalize(rhs);
 
-    let levenshtein_distance = levenshtein(&lhs, &rhs);
     let max_possible_distance = cmp::max(lhs.len(), rhs.len());
 
+    // Special case: If both strings are empty after normalization, then the strings should be
+    // considered equal and we can exit early. Otherwise we would divide by zero later on.
+    if max_possible_distance == 0 {
+        return Distance::MIN;
+    }
+
+    let levenshtein_distance = levenshtein(&lhs, &rhs);
+
     // FIXME: It's extremely unlikely, but this conversion to f64 is fallible. Hence, it should use
     // f64::try_from(usize) instead, but unfortunately that doesn't exist.
     Distance::from(levenshtein_distance as f64 / max_possible_distance as f64)

src/release_candidate.rs

@@ -136,3 +136,41 @@ impl<T: ReleaseLike> From<Vec<ReleaseCandidate<T>>> for ReleaseCandidateCollecti
         Self { candidates }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::{
+        distance::Distance,
+        release_candidate::{ReleaseCandidate, ReleaseCandidateCollection},
+        util::FakeRelease,
+        Config,
+    };
+
+    const RELEASE_DATA: &[u8] = include_bytes!(concat!(
+        env!("CARGO_MANIFEST_DIR"),
+        "/tests/data/debug/tuxedo/release.json"
+    ));
+    const RELEASE_CANDIDATE_0_DATA: &[u8] = include_bytes!(concat!(
+        env!("CARGO_MANIFEST_DIR"),
+        "/tests/data/debug/tuxedo/candidate_0.json"
+    ));
+
+    #[test]
+    fn test_track_assignment_exact() {
+        let release: FakeRelease = serde_json::from_slice(RELEASE_DATA).unwrap();
+        let candidate_0: FakeRelease = serde_json::from_slice(RELEASE_CANDIDATE_0_DATA).unwrap();
+
+        let config = Config::default();
+        let candidates = ReleaseCandidateCollection::from(
+            [candidate_0]
+                .into_iter()
+                .map(|candidate| ReleaseCandidate::with_base_release(candidate, &release, &config))
+                .collect::<Vec<_>>(),
+        );
+        let distances = candidates
+            .iter()
+            .map(|candidate| candidate.similarity().total_distance(&config))
+            .collect::<Vec<_>>();
+        assert_eq!(distances, [Distance::MIN]);
+    }
+}

src/util/mod.rs

@@ -16,7 +16,7 @@ mod time;
 
 pub use fs::{move_file, walk_dir};
 pub use keyed_binheap::KeyedBinaryHeap;
-#[cfg(feature = "dev")]
+#[cfg(any(test, feature = "dev"))]
 pub use testing::FakeRelease;
 #[cfg(test)]
 pub use testing::FakeTrack;