Test that all.css contains a valid CSS selector

Author: MaxDesiatov

.github/workflows/ci.yml

@@ -26,7 +26,7 @@ jobs:
           restore-keys: |
             ${{ runner.os }}-spm-xcode-${{ matrix.xcode }}-
       - name: Build and Test
-        run: swift test -c release
+        run: ./test.sh
         env:
           DEVELOPER_DIR: /Applications/Xcode_${{ matrix.xcode }}.app/Contents/Developer
 
@@ -54,4 +54,4 @@ jobs:
           apt-get update
           apt-get install -y libxml2-dev
       - name: Build and Test
-        run: swift test -c release --enable-test-discovery
+        run: ./test.sh

test.sh

@@ -0,0 +1,7 @@
+#!/bin/sh
+
+set -eux
+
+swift test -c release --enable-test-discovery
+./.build/release/swift-doc generate --module-name SwiftDoc --format html Sources
+grep ':root' ./.build/documentation/all.css || exit 1