rtk-ai/rtk · warning

f.txt entry

Error message

f.txt entry

What it means

This is a Rust test panic: `.expect("f.txt entry")` on `Iterator::position` aborts because the condensed diff output did not contain the line `[file] f.txt (+1 -1)`. The test asserts that a context line followed by `-a`/`+A` is grouped under the f.txt file header; when the filter's grouping changes (header format, ordering, or marker handling), the probe line is missing and `expect` panics. It is thrown by the library's own test suite, not at runtime by end users.

Solutions

  1. Run `rtk git diff` or the filter on the fixture manually and compare the emitted headers against the expected `[file] f.txt (+1 -1)` string.
  2. Update the test probe to the new header format if the format change was intentional, and refresh related snapshot files with `INSTA_UPDATE=always cargo test`.
  3. If the header should be unchanged, fix the regression in `condense_unified_diff_strict` (check marker/context-line grouping logic) and re-run the test.

Example fix

// before
.expect("f.txt entry");
// after
let f = lines.iter().position(|l| *l == "[file] f.txt (+1 -1)")
    .unwrap_or_else(|| panic!("f.txt header missing from output:\n{out}"));
Defensive patterns

Strategy: validation

Validate before calling

// assert the header format before snapshot-sensitive tests
let sample = condense_unified_diff_strict(FIXTURE).unwrap();
assert!(sample.contains("[file] "), "header format changed: {sample}");

Type guard

fn find_line<'a>(lines: &[&'a str], probe: &str) -> Option<usize> {
    lines.iter().position(|l| *l == probe)
}

Try / catch

// Rust tests panic, not catch: use Results and unwrap_or_else with context
let f = find_line(&lines, "[file] f.txt (+1 -1)")
    .unwrap_or_else(|| panic!("header missing:\n{out}"));

Prevention

When it happens

Trigger: Running `cargo test` for the strict unified-diff tests on fixture tests/fixtures/diff/git_diff_no_newline_raw.txt when `condense_unified_diff_strict` emits a different file header string, omits the f.txt entry, or reorders output so no line equals the exact probe string.

Common situations: A developer refactors the diff file-header formatting (e.g. changes `[file] name (+N -N)` wording), alters how no-newline-at-EOF markers are attached, or changes line grouping so context lines attach to a different file block — snapshot expectations silently break.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

AI-assisted analysis of rtk-ai/rtk@0924356b4c (2026-09-19). Data as JSON: /api/errors/ea21a1ebaaab88f4. Report an issue: GitHub.

Appendix: source

Thrown at src/cmds/git/diff_cmd.rs:6760

        let with_fact = format!("{fixture}Seulement dans b: h.txt\n");
        assert!(condense_unified_diff_strict(&with_fact).is_none());
    }

    #[test]
    fn no_newline_marker_stays_attached_to_the_line_it_describes() {
        // Real `git diff` of two files: `f.txt` changes its first line while
        // its unchanged last line lacks a newline (marker after a context
        // line), and `g.txt` gains a trailing newline (marker after `-y`).
        // The first marker used to land under `+A` and claim the ADDED line
        // had no newline; it must be dropped. The second is the witness of
        // a newline-only change and must stay right under `-y`.
        let fixture = include_str!("../../../tests/fixtures/diff/git_diff_no_newline_raw.txt");
        let out = condense_unified_diff_strict(fixture).expect("must parse");
        let lines: Vec<&str> = out.lines().collect();
        let f = lines
            .iter()
            .position(|l| *l == "[file] f.txt (+1 -1)")
            .expect("f.txt entry");
        assert_eq!(&lines[f..f + 3], &["[file] f.txt (+1 -1)", "-a", "+A"]);
        assert!(
            lines[f + 3].starts_with("[file] g.txt"),
            "marker after a context line leaked under +A:\n{out}"
        );
        let g = f + 3;
        assert_eq!(
            &lines[g..g + 4],
            &[
                "[file] g.txt (+1 -1)",
                "-y",
                "\\ No newline at end of file",
                "+y"
            ]
        );
    }

    #[test]

View on GitHub (pinned to 0924356b4c)