tests: add fuzzing to our test suite

[CommanderStorm]

This currently fails fairly fast, but that is expected.

Here is the minimized reproduciton:

use fastpfor::rust::{FastPFOR, Integer, BLOCK_SIZE_128, DEFAULT_PAGE_SIZE};
use std::io::Cursor;

let input = vec![42u32];
let mut codec = FastPFOR::new(DEFAULT_PAGE_SIZE, BLOCK_SIZE_128);
let mut compressed = vec![0u32; 1024];

let mut output_cur = Cursor::new(0);
codec.compress(&input, input.len() as u32, &mut Cursor::new(0), &mut compressed, &mut output_cur).unwrap();
assert!(output_cur.position() != 0); // Fails! We have compressed something to nothing :(

let mut decompressed = vec![0u32; 1024];
codec.uncompress(&compressed, output_cur.position(), &mut Cursor::new(0), &mut decompressed, &mut Cursor::new(0)).unwrap();

assert_eq!(decompressed, input);  // FAILS Input [42] -> Output []

[nyurik]

can the fuzzer be used for both C++ and Rust impl?

[CommanderStorm]

not one fuzzer, but I think having two is fair

[CommanderStorm]

the cpp fuzzer is not as fun though, because it does not immediately crash and burn..

The rust one is (for a fuzzer) basically made of very good firewood soaked in gasoline.

[nyurik]

hehe. I do think we need the same api for both ;)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 9 comments.

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[Copilot]

The fuzz job is missing Rust caching that is present in other CI jobs. Adding Swatinem/rust-cache@v2 (like in the test, test-nightly, and coverage jobs) would speed up builds by caching dependencies and compilation artifacts. This is especially important for fuzzing which may run frequently.

Suggested change

	with: {persist-credentials: false, submodules: recursive}
	with: {persist-credentials: false, submodules: recursive}
	- if: github.event_name != 'release' && github.event_name != 'workflow_dispatch'
	uses: Swatinem/rust-cache@v2

[Copilot]

The Integer trait is imported but never used in this fuzz target. Remove it from the import statement to clean up unused imports.

Suggested change

	use fastpfor::rust::{DEFAULT_PAGE_SIZE, FastPFOR, Integer};
	use fastpfor::rust::{DEFAULT_PAGE_SIZE, FastPFOR};

[Copilot]

The cargo fuzz commands are being run from the repository root, but they should be run from the fuzz directory. cargo-fuzz expects to be run from the directory containing the fuzz Cargo.toml. Add working-directory: fuzz to these steps or use cd fuzz && cargo fuzz ... to ensure the commands run in the correct directory.

Suggested change

	- run: cargo fuzz build --target x86_64-unknown-linux-gnu ${{ matrix.fuzz_target }}
	- run: cargo fuzz run --target x86_64-unknown-linux-gnu ${{ matrix.fuzz_target }} -- -max_total_time=${{ env.FUZZ_TIME }}
	- run: cargo fuzz build --target x86_64-unknown-linux-gnu ${{ matrix.fuzz_target }}
	working-directory: fuzz
	- run: cargo fuzz run --target x86_64-unknown-linux-gnu ${{ matrix.fuzz_target }} -- -max_total_time=${{ env.FUZZ_TIME }}
	working-directory: fuzz