tracing: add static level tests for spans and instrumented fns (tokio…

…-rs#1872)

The current tests for the compile-time maximum level were not being run
in `--release` mode, and did not previously assert anything about
`Span`s.

This also adds some test cases for various `#[instrument]`-ed functions.

.github/workflows/check_features.yml

@@ -0,0 +1,147 @@
+name: Check Features
+
+on:
+  push:
+    branches:
+    - master
+    - "v0.1.x"
+  pull_request: {}
+
+env:
+  # Disable incremental compilation.
+  #
+  # Incremental compilation is useful as part of an edit-build-test-edit cycle,
+  # as it lets the compiler avoid recompiling code that hasn't changed. However,
+  # on CI, we're not making small edits; we're almost always building the entire
+  # project from scratch. Thus, incremental compilation on CI actually
+  # introduces *additional* overhead to support making future builds
+  # faster...but no future builds will ever occur in any given CI environment.
+  #
+  # See https://matklad.github.io/2021/09/04/fast-rust-builds.html#ci-workflow
+  # for details.
+  CARGO_INCREMENTAL: 0
+  # Allow more retries for network requests in cargo (downloading crates) and
+  # rustup (installing toolchains). This should help to reduce flaky CI failures
+  # from transient network timeouts or other issues.
+  CARGO_NET_RETRY: 10
+  RUSTUP_MAX_RETRIES: 10
+  # Don't emit giant backtraces in the CI logs.
+  RUST_BACKTRACE: short
+
+jobs:
+  cargo-hack:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        # cargo hack --feature-powerset will have a significant permutation
+        # number, we can't just use --all as it increases the runtime
+        # further than what we would like to
+        subcrate:
+        - tracing-attributes
+        - tracing-core
+        - tracing-futures
+        - tracing-log
+        - tracing-macros
+        - tracing-serde
+        - tracing-tower
+        # tracing and tracing-subscriber have too many features to be checked by
+        # cargo-hack --feature-powerset, combinatorics there is exploding.
+        #- tracing
+        #- tracing-subscriber
+    steps:
+    - uses: actions/checkout@main
+    - uses: actions-rs/toolchain@v1
+      with:
+        toolchain: stable
+        profile: minimal
+        override: true
+    - name: Install cargo-hack
+      run: |
+        curl -LsSf https://github.com/taiki-e/cargo-hack/releases/latest/download/cargo-hack-x86_64-unknown-linux-gnu.tar.gz | tar xzf - -C ~/.cargo/bin
+    - name: cargo hack check
+      working-directory: ${{ matrix.subcrate }}
+      run: cargo hack check --feature-powerset --no-dev-deps
+
+  cargo-check-tracing:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        featureset:
+        - ""
+        - log-always
+        - std log-always
+        - std
+      fail-fast: false
+    steps:
+    - uses: actions/checkout@main
+    - uses: actions-rs/toolchain@v1
+      with:
+        toolchain: stable
+        profile: minimal
+        override: true
+    - name: cargo check
+      working-directory: tracing
+      run: cargo check --no-default-features --features "${{ matrix.featureset }}"
+
+  cargo-check-subscriber:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        featureset:
+        - ""
+        - fmt
+        - fmt ansi
+        - fmt json
+        - fmt json ansi
+        - fmt registry
+        - fmt env-filter
+        - registry
+        - env-filter
+    steps:
+    - uses: actions/checkout@main
+    - uses: actions-rs/toolchain@v1
+      with:
+        toolchain: stable
+        profile: minimal
+        override: true
+    - name: cargo check
+      working-directory: tracing-subscriber
+      run: cargo check --no-default-features --features "${{ matrix.featureset }}"
+
+  features-stable:
+    # Feature flag tests that run on stable Rust.
+    # TODO(david): once tracing's MSRV goes up to Rust 1.51, we should be able to switch to
+    # using cargo's V2 feature resolver (https://doc.rust-lang.org/cargo/reference/resolver.html#resolver-versions)
+    # and avoid cd'ing into each crate's directory.
+    needs: check
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@main
+    - uses: actions-rs/toolchain@v1
+      with:
+        toolchain: stable
+        profile: minimal
+        override: true
+    - name: "Test log support"
+      run: cargo test
+      working-directory: "tracing/test-log-support"
+    - name: "Test static max level"
+      run: cargo test
+      working-directory: "tracing/test_static_max_level_features"
+    - name: "Test tracing-core no-std support"
+      run: cargo test --no-default-features
+      working-directory: tracing-core
+    - name: "Test tracing no-std support"
+      run: cargo test --lib --tests --no-default-features
+      working-directory: tracing
+      # this skips running doctests under the `--no-default-features` flag,
+      # as rustdoc isn't aware of cargo's feature flags.
+    - name: "Test tracing-subscriber no-std support"
+      run: cargo test --lib --tests --no-default-features
+      working-directory: tracing-subscriber
+    - name: "Test tracing-subscriber with liballoc only"
+      run: cargo test --lib --tests --no-default-features --features "alloc"
+      working-directory: tracing-subscriber
+    - name: "Test tracing-subscriber with no default features"
+      run: cargo test --lib --tests --no-default-features --features "std"
+      working-directory: tracing-subscriber

tracing/test_static_max_level_features/tests/test.rs

@@ -53,6 +53,12 @@ fn last(state: &State, expected: Option<Level>) {
     assert_eq!(lvl, expected);
 }
 
+#[track_caller]
+fn last(state: &State, expected: Option<Level>) {
+    let lvl = state.last_level.lock().unwrap().take();
+    assert_eq!(lvl, expected);
+}
+
 #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
 #[test]
 fn test_static_max_level_events() {