Cached index in tests

Author: kornelski

.github/workflows/ci.yml

@@ -221,12 +221,23 @@ jobs:
     - name: Set Android Linker path
       if: endsWith(matrix.thing, '-android')
       run: echo "CARGO_TARGET_$(echo ${{ matrix.target }} | tr \\-a-z _A-Z)_LINKER=$ANDROID_NDK/toolchains/llvm/prebuilt/linux-x86_64/bin/$(echo ${{ matrix.target }} | sed s/armv7/armv7a/)21-clang++" >> "$GITHUB_ENV"
+    - name: Get rust version
+      id: rust-version
+      run: |
+        echo "version=$(rustc --version)" >> $GITHUB_OUTPUT
+    - name: Prepopulate cargo index
+      uses: actions/cache/restore@v4
+      with:
+        path: |
+          ~/.cargo/registry/index
+          ~/.cargo/registry/cache
+        key: index-${{ steps.rust-version.outputs.version }}-${{ hashFiles('Cargo.toml') }}
     - name: Build tests
       # We `build` because we want the linker to verify we are cross-compiling correctly for check-only targets.
       run: cargo build --target ${{ matrix.target }} --tests ${{ matrix.extra_test_args }}
       shell: bash
       env: ${{ matrix.custom_env }}
-    - name: Run tests
+    - name: Run tests (skip=${{ matrix.check_only }})
       if: "!matrix.check_only"
       run: cargo test --target ${{ matrix.target }} ${{ matrix.extra_test_args }}
       shell: bash