Add Comprehensive Tests for Backreference Behavior #15

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opened 2026-03-11 18:10:43 +03:00 by NiXTheDev · 0 comments

NiXTheDev commented

2026-03-11 18:10:43 +03:00

(Migrated from github.com)

Goal: Ensure backreferences (numbered, named, relative) work correctly in all edge cases.

Current tests cover basic backreferences, but need to include:

Relative backreferences with no numbered groups (should fail to match? Or treat as unmatchable).
Relative backreferences within named groups (group numbering exclusions).
Backreferences to groups that haven't been captured yet (e.g., forward reference) – should not match.
Multiple backreferences to the same group.
Backreferences inside quantified groups.
Nested backreferences.

Implementation Plan:
Create a new test module tests/backreference_edge_cases.rs (or add to existing) with specific test cases for each scenario. Use Regex::new and is_match/find to verify expected behavior.

Expected Behavior (to be defined):

If a backreference refers to a group that never captured (e.g., because it was in an unmatched alternative), it should not match.
Relative backreferences that go beyond the number of captured groups should cause the match to fail.

Example:

#[test]
fn relative_backref_without_enough_groups() {
    let re = Regex::new(r"(a)\g{-2}").unwrap(); // only one group, but -2 requested
    assert!(!re.is_match("aa"));
}

**Goal**: Ensure backreferences (numbered, named, relative) work correctly in all edge cases. Current tests cover basic backreferences, but need to include: - Relative backreferences with no numbered groups (should fail to match? Or treat as unmatchable). - Relative backreferences within named groups (group numbering exclusions). - Backreferences to groups that haven't been captured yet (e.g., forward reference) – should not match. - Multiple backreferences to the same group. - Backreferences inside quantified groups. - Nested backreferences. **Implementation Plan**: Create a new test module `tests/backreference_edge_cases.rs` (or add to existing) with specific test cases for each scenario. Use `Regex::new` and `is_match`/`find` to verify expected behavior. **Expected Behavior** (to be defined): - If a backreference refers to a group that never captured (e.g., because it was in an unmatched alternative), it should not match. - Relative backreferences that go beyond the number of captured groups should cause the match to fail. **Example**: ```rust #[test] fn relative_backref_without_enough_groups() { let re = Regex::new(r"(a)\g{-2}").unwrap(); // only one group, but -2 requested assert!(!re.is_match("aa")); } ```