ci: Implement test limitations and update Rust toolchain

- Added a new 'limited' test group to improve testing efficiency, ensuring maximum of 4 threads for specific test runs.
- Implemented an override to the Continuous Integration (CI) profile to filter and apply the 'limited' test group on `test(syscall::precompiles)`.
- Upgraded Rust toolchain from a 'nightly' to a 'stable' version for improved reliability and stability.

Author: huitseeker

.config/nextest.toml

@@ -10,3 +10,10 @@ fail-fast = false
 slow-timeout = { period = "300s", terminate-after = 4 }
 # Retry failed tests once, marked flaky if test then passes
 retries = 1
+
+[test-groups]
+limited = { max-threads = 4 }
+
+[[profile.ci.overrides]]
+filter = 'test(syscall::precompiles)'
+test-group = 'limited'

.github/workflows/tests.yml

@@ -33,7 +33,7 @@ jobs:
           cargo nextest run -p wp1-core --release --profile ci
       - name: Run cargo test on wp1-recursion-compiler, wp1-recursion-program, wp1-recursion-circuit
         run: |
-          cargo nextest run -p wp1-recursion-compiler --release --profile ci
+          cargo nextest run -p wp1-recursion-compiler -p wp1-recursion-program -p wp1-recursion-circuit --release --profile ci
       - name: Run cargo test with no default features
         run: |
           cargo nextest run -p wp1-core --release --profile ci --no-default-features --features debug -- cpu::trace::tests::generate_trace

rust-toolchain.toml

@@ -1,4 +1,4 @@
 [toolchain]
-channel = "nightly-2024-01-25"
+channel = "stable"
 profile = "default"
 components = ["llvm-tools", "rustc-dev"]