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Merged
sunshowers merged 1 commit into from
Mar 29, 2026
Merged

use hegel's ergonomic enum generator support #18

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194 changes: 98 additions & 96 deletions src/cursor/tests.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,10 +3,16 @@

// Property-based tests for Cursor.

// The DefaultGenerator derive generates PascalCase variable names for enum variants.
#![expect(non_snake_case)]

use crate::BufList;
use anyhow::{Context, Result, bail, ensure};
use bytes::{Buf, Bytes};
use hegel::{DefaultGenerator, generators};
// Import the Generator and DefaultGenerator *traits* (distinct from the DefaultGenerator derive
// macro imported above) so that .map() and .default_generator() are available.
use hegel::generators::DefaultGenerator as _;
use hegel::{DefaultGenerator, Generator, generators};
use std::{
fmt,
io::{self, BufRead, IoSliceMut, Read, Seek, SeekFrom},
Expand Down Expand Up @@ -51,102 +57,7 @@ fn buf_lists(tc: hegel::TestCase) -> BufList {
chunks.into_iter().map(Bytes::from).collect()
}

/// Unit enum for variant selection.
///
/// The derived DefaultGenerator picks a variant uniformly at random, without
/// generating any field data.
#[derive(Clone, Debug, DefaultGenerator)]
enum CursorOpKind {
SetPosition,
SeekStart,
SeekEnd,
SeekCurrent,
Read,
ReadVectored,
ReadExact,
Consume,
BufChunk,
BufAdvance,
BufChunksVectored,
BufCopyToBytes,
BufGetU8,
BufGetU64,
BufGetU64Le,
#[cfg(feature = "tokio1")]
PollRead,
}

#[hegel::composite]
fn cursor_ops(tc: hegel::TestCase, num_bytes: usize) -> CursorOp {
match tc.draw(generators::default::<CursorOpKind>()) {
CursorOpKind::SetPosition => {
// Allow going past the end of the list a bit.
let pos = tc.draw(generators::integers::<usize>().max_value(num_bytes * 5 / 4)) as u64;
CursorOp::SetPosition(pos)
}
CursorOpKind::SeekStart => {
// Allow going past the end of the list a bit.
let pos = tc.draw(generators::integers::<usize>().max_value(num_bytes * 5 / 4)) as u64;
CursorOp::SeekStart(pos)
}
CursorOpKind::SeekEnd => {
// Allow going past the beginning and end of the list a bit.
let raw = tc.draw(generators::integers::<usize>().max_value(num_bytes * 3 / 2));
let offset = raw as i64 - (1 + num_bytes * 5 / 4) as i64;
CursorOp::SeekEnd(offset)
}
CursorOpKind::SeekCurrent => {
let raw = tc.draw(generators::integers::<usize>().max_value(num_bytes * 3 / 2));
// Center the index at roughly 0.
let offset = raw as i64 - (num_bytes * 3 / 4) as i64;
CursorOp::SeekCurrent(offset)
}
CursorOpKind::Read => {
let buf_size = tc.draw(generators::integers::<usize>().max_value(num_bytes * 5 / 4));
CursorOp::Read(buf_size)
}
CursorOpKind::ReadVectored => {
let n_bufs = tc.draw(generators::integers::<usize>().max_value(7));
let sizes = (0..n_bufs)
.map(|_| tc.draw(generators::integers::<usize>().max_value(num_bytes)))
.collect();
CursorOp::ReadVectored(sizes)
}
CursorOpKind::ReadExact => {
let buf_size = tc.draw(generators::integers::<usize>().max_value(num_bytes * 5 / 4));
CursorOp::ReadExact(buf_size)
}
CursorOpKind::Consume => {
let amt = tc.draw(generators::integers::<usize>().max_value(num_bytes * 5 / 4));
CursorOp::Consume(amt)
}
CursorOpKind::BufChunk => CursorOp::BufChunk,
CursorOpKind::BufAdvance => {
let amt = tc.draw(generators::integers::<usize>().max_value(num_bytes * 5 / 4));
CursorOp::BufAdvance(amt)
}
CursorOpKind::BufChunksVectored => {
let num_iovs = tc.draw(generators::integers::<usize>().max_value(num_bytes));
CursorOp::BufChunksVectored(num_iovs)
}
CursorOpKind::BufCopyToBytes => {
let len = tc.draw(generators::integers::<usize>().max_value(num_bytes * 5 / 4));
CursorOp::BufCopyToBytes(len)
}
CursorOpKind::BufGetU8 => CursorOp::BufGetU8,
CursorOpKind::BufGetU64 => CursorOp::BufGetU64,
CursorOpKind::BufGetU64Le => CursorOp::BufGetU64Le,
#[cfg(feature = "tokio1")]
CursorOpKind::PollRead => {
let capacity = tc.draw(generators::integers::<usize>().max_value(num_bytes * 5 / 4));
// filled is in 0..=capacity, to sometimes fill the whole buffer.
let filled = tc.draw(generators::integers::<usize>().max_value(capacity));
CursorOp::PollRead { capacity, filled }
}
}
}

#[derive(Clone, Debug)]
enum CursorOp {
SetPosition(u64),
SeekStart(u64),
Expand Down Expand Up @@ -174,6 +85,97 @@ enum CursorOp {
},
}

/// Build a CursorOp generator with field constraints that depend on the
/// BufList's size.
///
/// Uses `#[derive(DefaultGenerator)]` on `CursorOp` for variant selection,
/// with per-variant field generators configured inline. This removes the need
/// for a separate discriminant enum.
fn cursor_ops(num_bytes: usize) -> impl Generator<CursorOp> {
// `d` provides access to default_*() methods for building per-variant generators.
let d = CursorOp::default_generator();

let gen = CursorOp::default_generator()
.SetPosition(
d.default_SetPosition()
// Allow going past the end of the list a bit.
.value(
generators::integers::<usize>()
.max_value(num_bytes * 5 / 4)
.map(|v| v as u64),
),
)
.SeekStart(
d.default_SeekStart()
// Allow going past the end of the list a bit.
.value(
generators::integers::<usize>()
.max_value(num_bytes * 5 / 4)
.map(|v| v as u64),
),
)
.SeekEnd(
d.default_SeekEnd()
// Allow going past the beginning and end of the list a bit.
.value(
generators::integers::<usize>()
.max_value(num_bytes * 3 / 2)
.map(move |raw| raw as i64 - (1 + num_bytes * 5 / 4) as i64),
),
)
.SeekCurrent(
d.default_SeekCurrent()
// Center the index at roughly 0.
.value(
generators::integers::<usize>()
.max_value(num_bytes * 3 / 2)
.map(move |raw| raw as i64 - (num_bytes * 3 / 4) as i64),
),
)
.Read(
d.default_Read()
.value(generators::integers::<usize>().max_value(num_bytes * 5 / 4)),
)
.ReadVectored(d.default_ReadVectored().value(
generators::vecs(generators::integers::<usize>().max_value(num_bytes)).max_size(7),
))
.ReadExact(
d.default_ReadExact()
.value(generators::integers::<usize>().max_value(num_bytes * 5 / 4)),
)
.Consume(
d.default_Consume()
.value(generators::integers::<usize>().max_value(num_bytes * 5 / 4)),
)
.BufAdvance(
d.default_BufAdvance()
.value(generators::integers::<usize>().max_value(num_bytes * 5 / 4)),
)
.BufChunksVectored(
d.default_BufChunksVectored()
.value(generators::integers::<usize>().max_value(num_bytes)),
)
.BufCopyToBytes(
d.default_BufCopyToBytes()
.value(generators::integers::<usize>().max_value(num_bytes * 5 / 4)),
);

#[cfg(feature = "tokio1")]
let gen = gen.PollRead(poll_read_op(num_bytes));

gen
}

/// Generates `CursorOp::PollRead` with the constraint that `filled <= capacity`.
#[cfg(feature = "tokio1")]
#[hegel::composite]
fn poll_read_op(tc: hegel::TestCase, num_bytes: usize) -> CursorOp {
let capacity = tc.draw(generators::integers::<usize>().max_value(num_bytes * 5 / 4));
// filled is in 0..=capacity, to sometimes fill the whole buffer.
let filled = tc.draw(generators::integers::<usize>().max_value(capacity));
CursorOp::PollRead { capacity, filled }
}

impl CursorOp {
fn apply_and_compare(
self,
Expand Down
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