Add macos-15 as a test environment

Author: smoelius

.github/workflows/ci.yml

@@ -33,8 +33,7 @@ jobs:
     strategy:
       fail-fast: ${{ github.event_name == 'merge_group' }}
       matrix:
-        # smoelius: Test with `macos-latest` once the repository is made public.
-        environment: [ubuntu-latest]
+        environment: [ubuntu-latest, macos-15]
         anchor-version: [0.31.1]
 
     runs-on: ${{ matrix.environment }}
@@ -76,11 +75,21 @@ jobs:
       - name: Rustup
         run: rustup update
 
-      - name: Install Agave prerequisites
-        run: |
+      - name: Install Agave prerequisites on Ubuntu
+        if: ${{ matrix.environment == 'ubuntu-latest' }}
           sudo apt update
           sudo apt install libclang-dev libudev-dev llvm protobuf-compiler
 
+      - name: Install Agave prerequisites on macOS
+        if: ${{ matrix.environment == 'macos-15' }}
+        run: |
+          brew install coreutils gnu-sed llvm protobuf
+          echo "/opt/homebrew/opt/gnu-sed/libexec/gnubin" >> "$GITHUB_PATH"
+          # smoelius: ~/lib is one of the directories `librocksdb-sys`'s build script checks
+          # for libclang.dylib.
+          mkdir ~/lib
+          ln -s /opt/homebrew/opt/llvm/lib/libclang.dylib ~/lib/libclang.dylib
+
       - name: Install Agave
         run: |
           if ! ./agave/bin/solana-test-validator --version; then