Backport DownloadSupportSpec & fix downloads

.github/workflows/gradle.yml

@@ -26,6 +26,10 @@ jobs:
       - name: "🔨 Build project"
         id: build
         run: ./gradlew build
+      - name: "🏃‍♀️Run functional tests"
+        run: |
+          cd spock-container-test-app
+          ./gradlew check
   publish:
     if: github.event_name == 'push'
     runs-on: ubuntu-latest

spock-container-test-app/src/integration-test/groovy/org/demo/spock/DownloadSupportSpec.groovy

@@ -0,0 +1,16 @@
+package org.demo.spock
+
+import grails.plugin.geb.ContainerGebSpec
+import grails.testing.mixin.integration.Integration
+
+@Integration
+class DownloadSupportSpec extends ContainerGebSpec {
+
+    void 'should be able to use download methods'() {
+        when:
+        go '/'
+
+        then:
+        downloadText().contains('Welcome to Grails')
+    }
+}

src/testFixtures/groovy/grails/plugin/geb/ContainerAwareDownloadSupport.groovy

@@ -40,5 +40,9 @@ trait ContainerAwareDownloadSupport implements DownloadSupport {
 
     @Delegate
     @Shared
-    DownloadSupport downloadSupport
+    static DownloadSupport downloadSupport
+
+    static void setDownloadSupport(DownloadSupport downloadSupport) {
+        this.downloadSupport = downloadSupport
+    }
 }