syntax/
fuzz.rs

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1//! Some infrastructure for fuzzy testing.
2//!
3//! We don't normally run fuzzying, so this is hopelessly bitrotten :(
4
5use std::str::{self, FromStr};
6
7use parser::Edition;
8
9use crate::{AstNode, SourceFile, TextRange, validation};
10
11fn check_file_invariants(file: &SourceFile) {
12    let root = file.syntax();
13    validation::validate_block_structure(root);
14}
15
16pub fn check_parser(text: &str) {
17    let file = SourceFile::parse(text, Edition::CURRENT);
18    check_file_invariants(&file.tree());
19}
20
21#[derive(Debug, Clone)]
22pub struct CheckReparse {
23    text: String,
24    delete: TextRange,
25    insert: String,
26    edited_text: String,
27}
28
29impl CheckReparse {
30    pub fn from_data(data: &[u8]) -> Option<Self> {
31        const PREFIX: &str = "fn main(){\n\t";
32        const SUFFIX: &str = "\n}";
33
34        let data = str::from_utf8(data).ok()?;
35        let mut lines = data.lines();
36        let delete_start = usize::from_str(lines.next()?).ok()? + PREFIX.len();
37        let delete_len = usize::from_str(lines.next()?).ok()?;
38        let insert = lines.next()?.to_owned();
39        let text = lines.collect::<Vec<_>>().join("\n");
40        let text = format!("{PREFIX}{text}{SUFFIX}");
41        text.get(delete_start..delete_start.checked_add(delete_len)?)?; // make sure delete is a valid range
42        let delete =
43            TextRange::at(delete_start.try_into().unwrap(), delete_len.try_into().unwrap());
44        let edited_text =
45            format!("{}{}{}", &text[..delete_start], &insert, &text[delete_start + delete_len..]);
46        Some(CheckReparse { text, insert, delete, edited_text })
47    }
48
49    #[allow(clippy::print_stderr)]
50    pub fn run(&self) {
51        let parse = SourceFile::parse(&self.text, Edition::CURRENT);
52        let new_parse = parse.reparse(self.delete, &self.insert, Edition::CURRENT);
53        check_file_invariants(&new_parse.tree());
54        assert_eq!(&new_parse.tree().syntax().text().to_string(), &self.edited_text);
55        let full_reparse = SourceFile::parse(&self.edited_text, Edition::CURRENT);
56        for (a, b) in
57            new_parse.tree().syntax().descendants().zip(full_reparse.tree().syntax().descendants())
58        {
59            if (a.kind(), a.text_range()) != (b.kind(), b.text_range()) {
60                eprint!("original:\n{:#?}", parse.tree().syntax());
61                eprint!("reparsed:\n{:#?}", new_parse.tree().syntax());
62                eprint!("full reparse:\n{:#?}", full_reparse.tree().syntax());
63                assert_eq!(
64                    format!("{a:?}"),
65                    format!("{b:?}"),
66                    "different syntax tree produced by the full reparse"
67                );
68            }
69        }
70        // FIXME
71        // assert_eq!(new_file.errors(), full_reparse.errors());
72    }
73}
syntax/fuzz.rs

syntax/
fuzz.rs
