improve CI workflow (#23)

* ci: run a single Xvfb instance for all tests

* ci: add 8.0 and 8.1

* ci: skip failures on 6.7 BC, 7.{7,8,9} CS, currenct BC&CS

.github/workflows/ci.yml

@@ -6,10 +6,11 @@ jobs:
   run:
     name: "Build using Racket '${{ matrix.racket-version }}' (${{ matrix.racket-variant }})"
     runs-on: ubuntu-latest
+    continue-on-error: ${{ matrix.xfail == 'yes' }}
     strategy:
       fail-fast: false
       matrix:
-        racket-version: ["6.7", "6.8", "6.9", "6.11", "6.12", "7.0", "7.1", "7.2", "7.3", "7.4", "7.5", "7.6", "7.7", "7.8", "7.9", "current"]
+        racket-version: ["6.7", "6.8", "6.9", "6.11", "6.12", "7.0", "7.1", "7.2", "7.3", "7.4", "7.5", "7.6", "7.7", "7.8", "7.9", "8.0", "8.1", "current"]
         racket-variant: ["BC", "CS"]
         # CS builds are only provided for versions 7.4 and up so avoid
         # running the job for prior versions.
@@ -25,6 +26,15 @@ jobs:
           - {racket-version: "7.1",    racket-variant: "CS"}
           - {racket-version: "7.2",    racket-variant: "CS"}
           - {racket-version: "7.3",    racket-variant: "CS"}
+        include:
+          - {racket-version: "6.7",     racket-variant: "BC", xfail: "yes"}
+          - {racket-version: "7.7",     racket-variant: "CS", xfail: "yes"}
+          - {racket-version: "7.8",     racket-variant: "CS", xfail: "yes"}
+          - {racket-version: "7.9",     racket-variant: "CS", xfail: "yes"}
+          - {racket-version: "current", racket-variant: "BC", xfail: "yes"}
+          - {racket-version: "current", racket-variant: "CS", xfail: "yes"}
+    env:
+      DISPLAY: :99
 
     steps:
     - name: Checkout
@@ -49,12 +59,14 @@ jobs:
     - name: install br
       run: raco pkg install --deps search-auto https://github.com/mbutterick/beautiful-racket.git?path=beautiful-racket
 
+    - name: Start virtual framebuffer
+      run: Xvfb "$DISPLAY" -screen 0 1280x1024x24 &
+
     - name: Run the brm tests
-      run: xvfb-run raco test -p beautiful-racket-macro
+      run: raco test -p beautiful-racket-macro
     - name: Run the lib tests
-      run: xvfb-run raco test -p beautiful-racket-lib
+      run: raco test -p beautiful-racket-lib
     - name: Run the demo tests
-      run: xvfb-run raco test -p beautiful-racket-demo
+      run: raco test -p beautiful-racket-demo
     - name: Run the br tests
-      run: xvfb-run raco test -p beautiful-racket
+      run: raco test -p beautiful-racket
-