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Verify stable formatting in fmt tests

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Richard Feldman 2022-05-06 11:10:12 -04:00
parent c0f18f1c52
commit eb8e7d6a97
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1 changed files with 48 additions and 1 deletions
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49
compiler/fmt/tests/test_fmt.rs
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@ -18,13 +18,60 @@ mod test_fmt {
// Not intended to be used directly in tests; please use expr_formats_to or expr_formats_same
fn expect_format_expr_helper(input: &str, expected: &str) {
let arena = Bump::new();
match roc_parse::test_helpers::parse_expr_with(&arena, input.trim()) {
let input = input.trim();
match roc_parse::test_helpers::parse_expr_with(&arena, input) {
Ok(actual) => {
use roc_fmt::spaces::RemoveSpaces;
let mut buf = Buf::new_in(&arena);
actual.format_with_options(&mut buf, Parens::NotNeeded, Newlines::Yes, 0);
let output = buf.as_str();
assert_multiline_str_eq!(expected, buf.as_str());
let reparsed_ast = roc_parse::test_helpers::parse_expr_with(&arena, output).unwrap_or_else(|err| {
panic!(
"After formatting, the source code no longer parsed!\n\nParse error was: {:?}\n\nThe code that failed to parse:\n\n{}\n\n",
err, output
);
});
let ast_normalized = actual.remove_spaces(&arena);
let reparsed_ast_normalized = reparsed_ast.remove_spaces(&arena);
// HACK!
// We compare the debug format strings of the ASTs, because I'm finding in practice that _somewhere_ deep inside the ast,
// the PartialEq implementation is returning `false` even when the Debug-formatted impl is exactly the same.
// I don't have the patience to debug this right now, so let's leave it for another day...
// TODO: fix PartialEq impl on ast types
if format!("{:?}", ast_normalized) != format!("{:?}", reparsed_ast_normalized) {
panic!(
"Formatting bug; formatting didn't reparse to the same AST (after removing spaces)\n\n\
* * * Source code before formatting:\n{}\n\n\
* * * Source code after formatting:\n{}\n\n",
input,
output
);
}
// Now verify that the resultant formatting is _stable_ - i.e. that it doesn't change again if re-formatted
let mut reformatted_buf = Buf::new_in(&arena);
reparsed_ast.format_with_options(&mut reformatted_buf, Parens::NotNeeded, Newlines::Yes, 0);
if output != reformatted_buf.as_str() {
panic!(
"Formatting bug; formatting is not stable. Reformatting the formatted code changed it again.\n\n\
Original input:\n{}\n\n\
After first formatting:\n{}\n\n\
After second formatting:\n{}\n\n",
input,
output,
reformatted_buf.as_str()
);
}
}
Err(error) => panic!("Unexpected parse failure when parsing this for formatting:\n\n{}\n\nParse error was:\n\n{:?}\n\n", input, error)
};