Add testing job on github actions

.github/workflows/ci.yml

@@ -13,3 +13,28 @@ jobs:
       run: gem install mdl
     - name: Run Markdown Lint
       run: mdl --git-recurse .
+
+  test:
+    runs-on: macos-latest
+
+    steps:
+    - uses: actions/checkout@v3
+
+    # Replace some binaries with a script that exits quickly, otherwise the build will time out or fail.
+    - name: Mock binaries
+      run: |
+        mkdir $HOME/bin
+
+        printf '#!'"/usr/bin/env bash\necho 'mas is overridden'" > $HOME/bin/mas
+        chmod +x $HOME/bin/mas
+    - name: Update PATH
+      run: |
+        echo "$HOME/bin" >> $GITHUB_PATH
+
+    - name: Unlink
+      run: |
+        rm '/usr/local/bin/aws'
+        rm '/usr/local/bin/aws_completer'
+
+    - run: make
+