feat(test): Improved test coverage for edge cases and errors

Author: PyDataBlog

tests/python/test_errors.py

@@ -0,0 +1,31 @@
+import pytest
+import multiprocessing
+import sys
+from simstring_rust.extractors import CustomExtractor
+from simstring_rust.database import HashDb
+
+def run_crashing_extractor():
+    class CrashingExtractor:
+        def apply(self, text):
+            raise ValueError("Crash!")
+
+    extractor = CustomExtractor(CrashingExtractor())
+    db = HashDb(extractor)
+    # This should panic the Rust side because of the unhandled exception in the callback
+    db.insert("foo")
+
+def test_custom_extractor_panic():
+    # Run the crashing code in a separate process
+    p = multiprocessing.Process(target=run_crashing_extractor)
+    p.start()
+    p.join()
+    
+    # Check if the process exited with an error (panic usually causes non-zero exit code)
+    assert p.exitcode != 0
+
+def test_custom_extractor_missing_apply():
+    class BadExtractor:
+        pass
+
+    with pytest.raises(TypeError, match="Custom extractor must provide an apply"):
+        CustomExtractor(BadExtractor())

tests/test_features.rs

@@ -229,3 +229,30 @@ mod word_ngrams_tests {
         );
     }
 }
+
+#[test]
+fn test_character_ngrams_input_shorter_than_n() {
+    // The condition `total_len < self.n` is only reachable if `text_len + 2*(n-1) < n`.
+    // This simplifies to `text_len + n < 2`.
+    // This is only possible if n=1 and text_len=0.
+    // For any n >= 2, the padding ensures total_len >= n.
+
+    let extractor = CharacterNgrams::new(1, "$");
+    let mut interner = Rodeo::default();
+
+    // "" -> len 0. n=1. padding=0. total_len=0. 0 < 1.
+    let features = extractor.features("", &mut interner);
+    assert!(
+        features.is_empty(),
+        "Features should be empty when input length is shorter than n (and n=1)"
+    );
+}
+
+#[test]
+fn test_word_ngrams_n_zero() {
+    let extractor = WordNgrams::new(0, " ", "#");
+    let mut interner = Rodeo::default();
+
+    let features = extractor.features("hello world", &mut interner);
+    assert!(features.is_empty(), "Features should be empty when n=0");
+}

tests/test_measures.rs

@@ -276,3 +276,77 @@ mod overlap_tests {
         assert_eq!(measure.minimum_common_feature_count(query_size, 5, 0.5), 3);
     }
 }
+
+// --- Edge Case Tests ---
+
+fn create_dummy_db() -> HashDb {
+    let feature_extractor = Arc::new(CharacterNgrams::new(2, "$"));
+    HashDb::new(feature_extractor)
+}
+
+#[test]
+fn test_cosine_edge_cases() {
+    let measure = Cosine;
+    let mut interner = Rodeo::default();
+    let x = vec![interner.get_or_intern("a")];
+    let empty = vec![];
+
+    // Similarity: Empty inputs
+    assert_eq!(measure.similarity(&empty, &empty), 0.0);
+    assert_eq!(measure.similarity(&x, &empty), 0.0);
+    assert_eq!(measure.similarity(&empty, &x), 0.0);
+
+    // max_feature_size: alpha = 0.0
+    let db = create_dummy_db();
+    // Should return db.max_feature_len() (which is 0 for empty db)
+    assert_eq!(measure.max_feature_size(5, 0.0, &db), 0);
+}
+
+#[test]
+fn test_dice_edge_cases() {
+    let measure = Dice;
+    let mut interner = Rodeo::default();
+    let x = vec![interner.get_or_intern("a")];
+    let empty = vec![];
+
+    // Similarity: Empty inputs
+    assert_eq!(measure.similarity(&empty, &empty), 1.0);
+    assert_eq!(measure.similarity(&x, &empty), 0.0);
+    assert_eq!(measure.similarity(&empty, &x), 0.0);
+
+    // min_feature_size: alpha > 2.0
+    assert_eq!(measure.min_feature_size(5, 2.1), 0);
+
+    // max_feature_size: alpha = 0.0
+    let db = create_dummy_db();
+    assert_eq!(measure.max_feature_size(5, 0.0, &db), 0);
+}
+
+#[test]
+fn test_jaccard_edge_cases() {
+    let measure = Jaccard;
+    let mut interner = Rodeo::default();
+    let x = vec![interner.get_or_intern("a")];
+    let empty = vec![];
+
+    // Similarity: Empty inputs
+    assert_eq!(measure.similarity(&empty, &empty), 1.0);
+    assert_eq!(measure.similarity(&x, &empty), 0.0);
+    assert_eq!(measure.similarity(&empty, &x), 0.0);
+
+    // minimum_common_feature_count: alpha = -1.0
+    assert_eq!(measure.minimum_common_feature_count(5, 5, -1.0), 0);
+}
+
+#[test]
+fn test_overlap_edge_cases() {
+    let measure = Overlap;
+    let mut interner = Rodeo::default();
+    let x = vec![interner.get_or_intern("a")];
+    let empty = vec![];
+
+    // Similarity: Empty inputs
+    assert_eq!(measure.similarity(&empty, &empty), 1.0);
+    assert_eq!(measure.similarity(&x, &empty), 0.0);
+    assert_eq!(measure.similarity(&empty, &x), 0.0);
+}