Move sr-arithmetic to a new crate and add in a fuzzer (#3799)

* Split up sr_arithmetic.rs

* Add some basic fuzzing

* Add more tests

* Add printing to fuzzing

* Clean things up

* Remove arbitrary

* Remove comments

* More cleaning, fix small error that was causing a panic

* Add rational128

* Remove old random tests

* introduce panic

* fuzzing should panic properly

* Bit of cleanup

* Add a test uncovered via fuzzing that fails!

* Few small changes

* Move sr-arithmetic to its own crate

* Fix fuzzing

* Got rid of fuzzer Cargo.lock

* Added no_std

* re-export assert_eq_error_rate

* bump impl and spec version

* re add convert into

* Add an ignore to the test

* Enabled benchmarking

* Reindent

* Clean up biguint fuzzer

* Clean up biguint more

* shuffle sr-primitives/traits about

* Remove unused dependencies

* Apply clippy suggestions

* upgrade primitive-types versions

* Run tests against num-bigint

* Get rid of allocation in assert_biguints_eq

* Add an optimisation to multiply_by_rational

* rename parts_per_x -> per_things

* Change fuzzer cargo.toml

* Remove allocation from BigUint PartialEq impl

* Remove accidental indentation

* Renmove Lazy and Convert traits

* Copy assert_eq_error_rate macro back to sr-primitives

* Add documentation to fuzzers

* fix sr-primitives assert_eq_error_rate

* add cfg(test)

* Update core/sr-arithmetic/src/traits.rs

Co-Authored-By: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* Update core/sr-arithmetic/src/traits.rs

Co-Authored-By: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* Update core/sr-arithmetic/fuzzer/src/biguint.rs

Co-Authored-By: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* Allow rounding up in rational128

* Make changes to biguint.rs

* Update core/sr-arithmetic/src/traits.rs

Co-Authored-By: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* Final touches

* Convert to num_bigint::BigUint to compare

* remove unused mut

* more small changes

* shuffle sr-primitives trait imports

* more code review

* move assert_eq_error_rate to lib.rs

* Update core/sr-arithmetic/fuzzer/src/biguint.rs

Co-Authored-By: Bastian Köcher <bkchr@users.noreply.github.com>

* Get rid of S

* Simplify rational128 honggfuzz link

* Insignificantly change rational128 fuzzing code

* Slightly tidy up some of the arithmetic logic

* Get rid of sr_arithmetic again(?) and fix sr-primitives/weights

* Apply updates to sr_arithmetic.rs to crate

Cargo.toml

@@ -53,6 +53,8 @@ members = [
 	"core/service/test",
 	"core/session",
 	"core/sr-api-macros",
+	"core/sr-arithmetic",
+	"core/sr-arithmetic/fuzzer",
 	"core/sr-io",
 	"core/sr-primitives",
 	"core/sr-staking-primitives",

core/sr-arithmetic/Cargo.toml

@@ -0,0 +1,26 @@
+[package]
+name = "sr-arithmetic"
+version = "2.0.0"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2018"
+
+[dependencies]
+num-traits = { version = "0.2.8", default-features = false }
+serde = { version = "1.0.101", optional = true, features = ["derive"] }
+codec = { package = "parity-scale-codec", version = "1.0.0", default-features = false, features = ["derive"] }
+rstd = { package = "sr-std", path = "../sr-std", default-features = false }
+integer-sqrt = "0.1.2"
+
+[dev-dependencies]
+primitive-types = "0.6.0"
+rand = "0.7.2"
+
+[features]
+bench = []
+default = ["std"]
+std = [
+	"serde",
+	"num-traits/std",
+	"rstd/std",
+	"codec/std",
+]

core/sr-arithmetic/fuzzer/.gitignore

@@ -0,0 +1,2 @@
+hfuzz_target
+hfuzz_workspace

core/sr-arithmetic/fuzzer/Cargo.toml

@@ -0,0 +1,20 @@
+[package]
+name = "sr-arithmetic-fuzzer"
+version = "2.0.0"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2018"
+
+[dependencies]
+sr-arithmetic = { path = ".." }
+honggfuzz = "0.5"
+primitive-types = "0.6"
+num-bigint = "0.2"
+num-traits = "0.2"
+
+[[bin]]
+name = "biguint"
+path = "src/biguint.rs"
+
+[[bin]]
+name = "rational128"
+path = "src/rational128.rs"