1 files changed, 80 insertions, 0 deletions
diff --git a/compiler/rustc_span/src/edit_distance/tests.rs b/compiler/rustc_span/src/edit_distance/tests.rs
new file mode 100644
index 000000000..c9c7a1f1b
--- /dev/null
+++ b/compiler/rustc_span/src/edit_distance/tests.rs
@@ -0,0 +1,80 @@
+use super::*;
+
+#[test]
+fn test_edit_distance() {
+    // Test bytelength agnosticity
+    for c in (0..char::MAX as u32).filter_map(char::from_u32).map(|i| i.to_string()) {
+        assert_eq!(edit_distance(&c[..], &c[..], usize::MAX), Some(0));
+    }
+
+    let a = "\nMäry häd ä little lämb\n\nLittle lämb\n";
+    let b = "\nMary häd ä little lämb\n\nLittle lämb\n";
+    let c = "Mary häd ä little lämb\n\nLittle lämb\n";
+    assert_eq!(edit_distance(a, b, usize::MAX), Some(1));
+    assert_eq!(edit_distance(b, a, usize::MAX), Some(1));
+    assert_eq!(edit_distance(a, c, usize::MAX), Some(2));
+    assert_eq!(edit_distance(c, a, usize::MAX), Some(2));
+    assert_eq!(edit_distance(b, c, usize::MAX), Some(1));
+    assert_eq!(edit_distance(c, b, usize::MAX), Some(1));
+}
+
+#[test]
+fn test_edit_distance_limit() {
+    assert_eq!(edit_distance("abc", "abcd", 1), Some(1));
+    assert_eq!(edit_distance("abc", "abcd", 0), None);
+    assert_eq!(edit_distance("abc", "xyz", 3), Some(3));
+    assert_eq!(edit_distance("abc", "xyz", 2), None);
+}
+
+#[test]
+fn test_method_name_similarity_score() {
+    assert_eq!(edit_distance_with_substrings("empty", "is_empty", 1), Some(1));
+    assert_eq!(edit_distance_with_substrings("shrunk", "rchunks", 2), None);
+    assert_eq!(edit_distance_with_substrings("abc", "abcd", 1), Some(1));
+    assert_eq!(edit_distance_with_substrings("a", "abcd", 1), None);
+    assert_eq!(edit_distance_with_substrings("edf", "eq", 1), None);
+    assert_eq!(edit_distance_with_substrings("abc", "xyz", 3), Some(3));
+    assert_eq!(edit_distance_with_substrings("abcdef", "abcdef", 2), Some(0));
+}
+
+#[test]
+fn test_find_best_match_for_name() {
+    use crate::create_default_session_globals_then;
+    create_default_session_globals_then(|| {
+        let input = vec![Symbol::intern("aaab"), Symbol::intern("aaabc")];
+        assert_eq!(
+            find_best_match_for_name(&input, Symbol::intern("aaaa"), None),
+            Some(Symbol::intern("aaab"))
+        );
+
+        assert_eq!(find_best_match_for_name(&input, Symbol::intern("1111111111"), None), None);
+
+        let input = vec![Symbol::intern("AAAA")];
+        assert_eq!(
+            find_best_match_for_name(&input, Symbol::intern("aaaa"), None),
+            Some(Symbol::intern("AAAA"))
+        );
+
+        let input = vec![Symbol::intern("AAAA")];
+        assert_eq!(
+            find_best_match_for_name(&input, Symbol::intern("aaaa"), Some(4)),
+            Some(Symbol::intern("AAAA"))
+        );
+
+        let input = vec![Symbol::intern("a_longer_variable_name")];
+        assert_eq!(
+            find_best_match_for_name(&input, Symbol::intern("a_variable_longer_name"), None),
+            Some(Symbol::intern("a_longer_variable_name"))
+        );
+    })
+}
+
+#[test]
+fn test_precise_algorithm() {
+    // Not Levenshtein distance.
+    assert_ne!(edit_distance("ab", "ba", usize::MAX), Some(2));
+    // Not unrestricted Damerau-Levenshtein distance.
+    assert_ne!(edit_distance("abde", "bcaed", usize::MAX), Some(3));
+    // The current implementation is a restricted Damerau-Levenshtein distance.
+    assert_eq!(edit_distance("abde", "bcaed", usize::MAX), Some(4));
+}