Update cmake.yml

Author: kcotto

.github/workflows/cmake.yml

@@ -16,10 +16,18 @@ jobs:
     # well on Windows or Mac.  You can convert this to a matrix build if you need
     # cross-platform coverage.
     # See: https://docs.github.com/en/free-pro-team@latest/actions/learn-github-actions/managing-complex-workflows#using-a-build-matrix
-    runs-on: ubuntu-latest
-
+    strategy: 
+      os: [ubuntu-latest, macos-latest]
+    
+    runs-on: ${{ matrix.os }}
+    
     steps:
     - uses: actions/checkout@v2
+    
+    - name: Install packages (macOS)
+        if: contains(matrix.os,'macos')
+        run: |
+          brew update || brew install lcov || gem install coveralls-lcov
 
     - name: Configure CMake
       # Configure CMake in a 'build' subdirectory. `CMAKE_BUILD_TYPE` is only required if you are using a single-configuration generator such as make.