More testing and fuzzing and docs for pools

Cargo.toml

@@ -116,6 +116,7 @@ members = [
 	"frame/preimage",
 	"frame/proxy",
 	"frame/nomination-pools",
+	"frame/nomination-pools/fuzzer",
 	"frame/nomination-pools/benchmarking",
 	"frame/nomination-pools/test-staking",
 	"frame/nomination-pools/runtime-api",

frame/balances/src/lib.rs

@@ -477,7 +477,7 @@ pub mod pallet {
 		VestingBalance,
 		/// Account liquidity restrictions prevent withdrawal
 		LiquidityRestrictions,
-		/// Balance too low to send value
+		/// Balance too low to send value.
 		InsufficientBalance,
 		/// Value too low to create account due to existential deposit
 		ExistentialDeposit,

frame/nomination-pools/Cargo.toml

@@ -26,13 +26,17 @@ sp-core = { version = "6.0.0", default-features = false, path = "../../primitive
 sp-io = { version = "6.0.0", default-features = false, path = "../../primitives/io" }
 log = { version = "0.4.0", default-features = false }
 
+# Optional: usef for testing and/or fuzzing
+pallet-balances = { version = "4.0.0-dev", path = "../balances", optional = true }
+sp-tracing = { version = "5.0.0", path = "../../primitives/tracing", optional = true }
+
 [dev-dependencies]
 pallet-balances = { version = "4.0.0-dev", path = "../balances" }
 sp-tracing = { version = "5.0.0", path = "../../primitives/tracing" }
-rand = { version = "0.8.5", features = ["small_rng"] }
 
 [features]
 default = ["std"]
+fuzzing = ["pallet-balances", "sp-tracing"]
 std = [
 	"codec/std",
 	"scale-info/std",
@@ -51,4 +55,3 @@ runtime-benchmarks = [
 try-runtime = [
 	"frame-support/try-runtime"
 ]
-fuzz-test = []

frame/nomination-pools/fuzzer/Cargo.toml

@@ -0,0 +1,33 @@
+[package]
+name = "pallet-nomination-pools-fuzzer"
+version = "2.0.0"
+authors = ["Parity Technologies <[email protected]>"]
+edition = "2021"
+license = "Apache-2.0"
+homepage = "https://substrate.io"
+repository = "https://github.com/paritytech/substrate/"
+description = "Fuzzer for fixed point arithmetic primitives."
+documentation = "https://docs.rs/sp-arithmetic-fuzzer"
+publish = false
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]
+
+[dependencies]
+honggfuzz = "0.5.54"
+
+pallet-nomination-pools = { path = "..", features = ["fuzzing"] }
+
+frame-system = { path = "../../system" }
+frame-support = { path = "../../support" }
+
+sp-runtime = { path = "../../../primitives/runtime" }
+sp-io = { path = "../../../primitives/io" }
+sp-tracing = { path = "../../../primitives/tracing" }
+
+rand = { version = "0.8.5", features = ["small_rng"] }
+log = "0.4.17"
+
+[[bin]]
+name = "call"
+path = "src/call.rs"