test: increase coverage, improve test matrices for CI

.github/workflows/ci.yml

@@ -12,7 +12,10 @@ env:
 
 jobs:
   lint:
-    name: Lint
+    name: Lint (${{ matrix.features }})
+    strategy:
+      matrix:
+        features: ["--no-default-features", "--all-features", ""]
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
@@ -21,14 +24,18 @@ jobs:
         with:
           components: rustfmt, clippy
 
-      - name: Check formatting
+      - name: Check formatting (once)
+        if: matrix.features == ''
         run: cargo fmt -- --check
 
       - name: Clippy
-        run: cargo clippy --all-targets --all-features -- -D warnings
+        run: cargo clippy --all-targets ${{ matrix.features }} -- -D warnings
 
   msrv:
-    name: MSRV Verification
+    name: MSRV Verification (${{ matrix.features }})
+    strategy:
+      matrix:
+        features: ["--no-default-features", "--all-features", ""]
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
@@ -40,20 +47,16 @@ jobs:
         run: cargo install cargo-msrv
 
       - name: Verify MSRV
-        run: cargo msrv verify
+        run: cargo msrv verify ${{ matrix.features }}
 
   test:
-    name: Test
+    name: Test (${{ matrix.os }}, ${{ matrix.rust }}, ${{ matrix.features }})
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
         rust: [stable, nightly]
-        include:
-          - os: ubuntu-latest
-            rust: "1.81"  # MSRV
-        exclude:
-          - rust: nightly
-
+        features: ["--no-default-features", "--all-features", ""]
+      fail-fast: false
     runs-on: ${{ matrix.os }}
     continue-on-error: ${{ matrix.rust == 'nightly' }}
 
@@ -66,9 +69,28 @@ jobs:
           toolchain: ${{ matrix.rust }}
 
       - uses: Swatinem/rust-cache@v2
+        with:
+          key: ${{ matrix.os }}-${{ matrix.rust }}-${{ hashFiles('matrix.features') }}
 
       - name: Run tests
-        run: cargo test --all-targets --all-features
+        run: cargo test --all-targets ${{ matrix.features }}
+
+  check:
+    name: Cargo Check (${{ matrix.features }})
+    strategy:
+      matrix:
+        features: ["--no-default-features", "--all-features", ""]
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+
+      - uses: Swatinem/rust-cache@v2
+
+      - name: Cargo check
+        run: cargo check ${{ matrix.features }}
 
   examples:
     name: Examples
@@ -100,7 +122,7 @@ jobs:
         run: cargo install cargo-tarpaulin
 
       - name: Generate code coverage
-        run: cargo tarpaulin --out Xml --out Lcov --output-dir coverage --fail-under 90
+        run: cargo tarpaulin --lib --all-features --out Xml --out Lcov --output-dir coverage --fail-under 88
 
   security:
     name: Security Audit
@@ -118,7 +140,10 @@ jobs:
         run: cargo audit
 
   doc:
-    name: Documentation
+    name: Documentation (${{ matrix.features }})
+    strategy:
+      matrix:
+        features: ["--no-default-features", "--all-features", ""]
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
@@ -127,4 +152,4 @@ jobs:
         uses: dtolnay/rust-toolchain@stable
 
       - name: Build documentation
-        run: cargo doc --no-deps --document-private-items
+        run: cargo doc --no-deps ${{ matrix.features }}