Remove once_cell dep by replacing once_cell::sync::OnceCell with std::sync::OnceLock

.github/workflows/ci.yml

@@ -37,7 +37,7 @@ jobs:
     - name: Install Rust ${{ matrix.rust_version }}
       run: rustup default ${{ matrix.rust_version }}
     - name: Run Tests
-      run: cargo test --no-default-features --features=prost -- --test-threads=1
+      run: cargo test --no-default-features --features=prost
   cross-test:
     name: Test ${{ matrix.target }}
     runs-on: ubuntu-latest
@@ -55,7 +55,7 @@ jobs:
     - name: Install Cross
       run: cargo install cross --git https://github.com/cross-rs/cross
     - name: Run Tests
-      run: cross test --target ${{ matrix.target }} --no-default-features --features=prost -- --test-threads=1
+      run: cross test --target ${{ matrix.target }} --no-default-features --features=prost
   cross-test-mips-mipssel:
     name: Test ${{ matrix.target }}
     runs-on: ubuntu-latest
@@ -71,7 +71,7 @@ jobs:
     - name: Install Cross
       run: cargo install cross --git https://github.com/cross-rs/cross
     - name: Run Tests
-      run: cross +nightly test --target ${{ matrix.target }} --no-default-features --features=prost -- --test-threads=1
+      run: cross +nightly test --target ${{ matrix.target }} --no-default-features --features=prost
       env:
         RUSTFLAGS: "-C opt-level=1"
   test-wasm-browser:

Cargo.toml

@@ -37,7 +37,6 @@ flaky_tests = []
 prost = ["prost-types"]
 
 [dependencies]
-once_cell = "1.4"
 prost-types = { version = "0.11", default-features = false, optional = true }
 crossbeam-utils = "0.8.5"
 
@@ -62,6 +61,7 @@ wasi = "0.11"
 [dev-dependencies]
 average = "0.14"
 criterion = "=0.3.3"
+serial_test = "3.2"
 
 [target.'cfg(all(target_arch = "wasm32", target_os = "unknown"))'.dev-dependencies]
 wasm-bindgen-test = "0.3"

src/instant.rs

@@ -279,20 +279,18 @@ impl Into<prost_types::Timestamp> for Instant {
 
 #[cfg(test)]
 mod tests {
-    use once_cell::sync::Lazy;
-
     use super::Instant;
     use crate::{with_clock, Clock};
+    use serial_test::serial;
+    use std::thread;
     use std::time::Duration;
-    use std::{sync::Mutex, thread};
-
-    static RECENT_LOCK: Lazy<Mutex<()>> = Lazy::new(|| Mutex::new(()));
 
     #[test]
     #[cfg_attr(
         all(target_arch = "wasm32", target_os = "unknown"),
         ignore = "WASM thread cannot sleep"
     )]
+    #[serial]
     fn test_now() {
         let t0 = Instant::now();
         thread::sleep(Duration::from_millis(15));
@@ -311,9 +309,8 @@ mod tests {
         all(target_arch = "wasm32", target_os = "unknown"),
         ignore = "WASM thread cannot sleep"
     )]
+    #[serial]
     fn test_recent() {
-        let _guard = RECENT_LOCK.lock().unwrap();
-
         // Ensures that the recent global value is zero so that the fallback logic can kick in.
         crate::set_recent(Instant(0));
 
@@ -346,9 +343,8 @@ mod tests {
         all(target_arch = "wasm32", target_os = "unknown"),
         wasm_bindgen_test::wasm_bindgen_test
     )]
+    #[serial]
     fn test_mocking() {
-        let _guard = RECENT_LOCK.lock().unwrap();
-
         // Ensures that the recent global value is zero so that the fallback logic can kick in.
         crate::set_recent(Instant(0));
 
@@ -380,6 +376,7 @@ mod tests {
         all(target_arch = "wasm32", target_os = "unknown"),
         wasm_bindgen_test::wasm_bindgen_test
     )]
+    #[serial]
     fn checked_arithmetic_u64_overflow() {
         fn nanos_to_dur(total_nanos: u128) -> Duration {
             let nanos_per_sec = Duration::from_secs(1).as_nanos();

src/lib.rs

@@ -141,11 +141,10 @@
 #![allow(clippy::must_use_candidate)]
 
 use crossbeam_utils::atomic::AtomicCell;
+use std::sync::OnceLock;
 use std::time::Duration;
 use std::{cell::RefCell, sync::Arc};
 
-use once_cell::sync::OnceCell;
-
 mod clocks;
 use self::clocks::{Counter, Monotonic};
 mod detection;
@@ -159,13 +158,13 @@ mod stats;
 use self::stats::Variance;
 
 // Global clock, used by `Instant::now`.
-static GLOBAL_CLOCK: OnceCell<Clock> = OnceCell::new();
+static GLOBAL_CLOCK: OnceLock<Clock> = OnceLock::new();
 
 // Global recent measurement, used by `Clock::recent` and `Instant::recent`.
 static GLOBAL_RECENT: AtomicCell<u64> = AtomicCell::new(0);
 
 // Global calibration, shared by all clocks.
-static GLOBAL_CALIBRATION: OnceCell<Calibration> = OnceCell::new();
+static GLOBAL_CALIBRATION: OnceLock<Calibration> = OnceLock::new();
 
 // Per-thread clock override, used by `quanta::with_clock`, `Instant::now`, and sometimes `Instant::recent`.
 thread_local! {
@@ -543,6 +542,7 @@ fn mul_div_po2_u64(value: u64, numer: u64, denom: u32) -> u64 {
 #[cfg(test)]
 mod tests {
     use super::Clock;
+    use serial_test::serial;
 
     #[cfg(not(target_arch = "wasm32"))]
     use super::{Counter, Monotonic};
@@ -558,6 +558,7 @@ mod tests {
         all(target_arch = "wasm32", target_os = "unknown"),
         wasm_bindgen_test::wasm_bindgen_test
     )]
+    #[serial]
     fn test_mock() {
         let (clock, mock) = Clock::mock();
         assert_eq!(clock.now().0, 0);
@@ -566,6 +567,7 @@ mod tests {
     }
 
     #[test]
+    #[serial]
     #[cfg_attr(
         all(target_arch = "wasm32", target_os = "unknown"),
         wasm_bindgen_test::wasm_bindgen_test
@@ -576,6 +578,7 @@ mod tests {
     }
 
     #[test]
+    #[serial]
     #[cfg_attr(
         all(target_arch = "wasm32", target_os = "unknown"),
         wasm_bindgen_test::wasm_bindgen_test
@@ -586,6 +589,7 @@ mod tests {
     }
 
     #[test]
+    #[serial]
     #[cfg_attr(
         all(target_arch = "wasm32", target_os = "unknown"),
         wasm_bindgen_test::wasm_bindgen_test
@@ -599,6 +603,7 @@ mod tests {
 
     #[cfg(not(target_arch = "wasm32"))]
     #[test]
+    #[serial]
     #[cfg_attr(not(feature = "flaky_tests"), ignore)]
     fn test_reference_source_calibration() {
         let mut clock = Clock::new();
@@ -682,6 +687,7 @@ mod tests {
 
     #[cfg(not(target_arch = "wasm32"))]
     #[test]
+    #[serial]
     #[cfg_attr(not(feature = "flaky_tests"), ignore)]
     fn measure_source_reference_self_timing() {
         let source = Counter::default();

src/stats.rs

@@ -61,8 +61,10 @@ impl Variance {
 #[cfg(test)]
 mod tests {
     use super::Variance;
+    use serial_test::serial;
 
     #[test]
+    #[serial]
     fn basic() {
         let inputs = &[5.0, 10.0, 12.0, 15.0, 20.0];
         let mut variance = Variance::default();

src/upkeep.rs

@@ -170,10 +170,12 @@ impl Drop for Handle {
 #[cfg(test)]
 mod tests {
     use super::Upkeep;
+    use serial_test::serial;
     use std::time::Duration;
 
     #[test]
     #[cfg_attr(target_arch = "wasm32", ignore)] // WASM is single threaded
+    #[serial]
     fn test_spawning_second_upkeep() {
         let first = Upkeep::new(Duration::from_millis(250)).start();
         let second = Upkeep::new(Duration::from_millis(250))