1 files changed, 48 insertions, 0 deletions
diff --git a/nearby/presence/rand_ext/src/lib.rs b/nearby/presence/rand_ext/src/lib.rs
new file mode 100644
index 0000000..8f93aac
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+++ b/nearby/presence/rand_ext/src/lib.rs
@@ -0,0 +1,48 @@
+// Copyright 2022 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Helper functions around `rand`'s offerings for convenient test usage.
+#![no_std]
+#![forbid(unsafe_code)]
+#![deny(missing_docs)]
+
+extern crate alloc;
+
+use alloc::vec::Vec;
+use log::info;
+pub use rand;
+use rand::{Rng as _, SeedableRng as _};
+
+/// Returns a random vec with the provided length.
+pub fn random_vec<R: rand::Rng>(rng: &mut R, len: usize) -> Vec<u8> {
+    let mut bytes = Vec::<u8>::new();
+    bytes.extend((0..len).into_iter().map(|_| rng.gen::<u8>()));
+    bytes
+}
+
+/// Returns a random array with the provided length.
+pub fn random_bytes<const B: usize, R: rand::Rng>(rng: &mut R) -> [u8; B] {
+    let mut bytes = [0; B];
+    rng.fill(bytes.as_mut_slice());
+    bytes
+}
+
+/// Returns a fast rng seeded with the thread rng (which is itself seeded from the OS).
+pub fn seeded_rng() -> impl rand::Rng {
+    let mut seed: <rand_pcg::Pcg64 as rand::SeedableRng>::Seed = Default::default();
+    rand::thread_rng().fill(&mut seed);
+    // print it out so if a test fails, the seed will be visible for further investigation
+    info!("seed: {:?}", seed);
+    rand_pcg::Pcg64::from_seed(seed)
+}