tvl-depot/tvix/eval/tests/nix_oracle.rs

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//! Tests which use upstream nix as an oracle to test evaluation against
use std::{env, path::PathBuf, process::Command};
use pretty_assertions::assert_eq;
fn nix_binary_path() -> PathBuf {
env::var("NIX_INSTANTIATE_BINARY_PATH")
.unwrap_or_else(|_| "nix-instantiate".to_owned())
.into()
}
#[derive(Clone, Copy)]
enum Strictness {
Lazy,
Strict,
}
fn nix_eval(expr: &str, strictness: Strictness) -> String {
let store_dir = tempfile::tempdir().unwrap();
let mut args = match strictness {
Strictness::Lazy => vec![],
Strictness::Strict => vec!["--strict"],
};
args.extend_from_slice(&["--eval", "-E"]);
let output = Command::new(nix_binary_path())
.args(&args[..])
.arg(format!("({expr})"))
.env(
"NIX_REMOTE",
format!(
"local?root={}",
store_dir
.path()
.canonicalize()
.expect("valid path")
.display()
),
)
.output()
.unwrap();
if !output.status.success() {
panic!(
"nix eval {expr} failed!\n stdout: {}\n stderr: {}",
String::from_utf8_lossy(&output.stdout),
String::from_utf8_lossy(&output.stderr)
)
}
String::from_utf8(output.stdout).unwrap()
}
/// Compare the evaluation of the given nix expression in nix (using the
/// `NIX_INSTANTIATE_BINARY_PATH` env var to resolve the `nix-instantiate` binary) and tvix, and
/// assert that the result is identical
#[track_caller]
fn compare_eval(expr: &str, strictness: Strictness) {
let nix_result = nix_eval(expr, strictness);
let mut eval = tvix_eval::Evaluation::new_pure();
eval.strict = matches!(strictness, Strictness::Strict);
eval.io_handle = Box::new(tvix_eval::StdIO);
let tvix_result = eval
.evaluate(expr, None)
.value
.expect("tvix evaluation should succeed")
.to_string();
assert_eq!(nix_result.trim(), tvix_result);
}
/// Generate a suite of tests which call [`compare_eval`] on expressions, checking that nix and tvix
/// return identical results.
macro_rules! compare_eval_tests {
($strictness:expr, {}) => {};
($strictness:expr, {$(#[$meta:meta])* $test_name: ident($expr: expr); $($rest:tt)*}) => {
#[test]
$(#[$meta])*
fn $test_name() {
compare_eval($expr, $strictness);
}
compare_eval_tests!($strictness, { $($rest)* });
}
}
macro_rules! compare_strict_eval_tests {
($($tests:tt)*) => {
compare_eval_tests!(Strictness::Strict, { $($tests)* });
}
}
macro_rules! compare_lazy_eval_tests {
($($tests:tt)*) => {
compare_eval_tests!(Strictness::Lazy, { $($tests)* });
}
}
compare_strict_eval_tests! {
literal_int("1");
add_ints("1 + 1");
add_lists("[1 2] ++ [3 4]");
add_paths(r#"[
(./. + "/")
(./foo + "bar")
(let name = "bar"; in ./foo + name)
(let name = "bar"; in ./foo + "${name}")
(let name = "bar"; in ./foo + "/" + "${name}")
(let name = "bar"; in ./foo + "/${name}")
(./. + ./.)
]"#);
}
// TODO(sterni): tvix_tests should gain support for something similar in the future,
// but this requires messing with the path naming which would break compat with
// C++ Nix's test suite
compare_lazy_eval_tests! {
// Wrap every expression type supported by [Compiler::compile] in a list
// with lazy evaluation enabled, so we can check it being thunked or not
// against C++ Nix.
unthunked_literals_in_list("[ https://tvl.fyi 1 1.2 ]");
unthunked_path_in_list("[ ./nix_oracle.rs ]");
unthunked_string_literal_in_list("[ \":thonking:\" ]");
thunked_unary_ops_in_list("[ (!true) (-1) ]");
thunked_bin_ops_in_list(r#"
let
# Necessary to fool the optimiser for && and ||
true' = true;
false' = false;
in
[
(true' && false')
(true' || false')
(false -> true)
(40 + 2)
(43 - 1)
(21 * 2)
(126 / 3)
({ } // { bar = null; })
(12 == 13)
(3 < 2)
(4 > 2)
(23 >= 42)
(33 <= 22)
([ ] ++ [ ])
(42 != null)
]
"#);
thunked_has_attrs_in_list("[ ({ } ? foo) ]");
thunked_list_in_list("[ [ 1 2 3 ] ]");
thunked_attr_set_in_list("[ { foo = null; } ]");
thunked_select_in_list("[ ({ foo = null; }.bar) ]");
thunked_assert_in_list("[ (assert false; 12) ]");
thunked_if_in_list("[ (if false then 13 else 12) ]");
thunked_let_in_list("[ (let foo = 12; in foo) ]");
thunked_with_in_list("[ (with { foo = 13; }; fooo) ]");
unthunked_identifier_in_list("let foo = 12; in [ foo ]");
thunked_lambda_in_list("[ (x: x) ]");
thunked_function_application_in_list("[ (builtins.add 1 2) ]");
thunked_legacy_let_in_list("[ (let { foo = 12; body = foo; }) ]");
unthunked_relative_path("[ ./foo ]");
unthunked_home_relative_path("[ ~/foo ]");
unthunked_absolute_path("[ /foo ]");
unthunked_formals_fallback_literal("({ foo ? 12 }: [ foo ]) { }");
unthunked_formals_fallback_string_literal("({ foo ? \"wiggly\" }: [ foo ]) { }");
thunked_formals_fallback_application("({ foo ? builtins.add 1 2 }: [ foo ]) { }");
thunked_formals_fallback_name_resolution_literal("({ foo ? bar, bar ? 12 }: [ foo ]) { }");
}