Add unit test which registers cache manager

src/test/groovy/com/demo/BasicCachingServiceNoCacheManagerSpec.groovy

@@ -0,0 +1,24 @@
+package com.demo
+
+import grails.test.mixin.TestFor
+import spock.lang.Specification
+
+@TestFor(BasicCachingService)
+class BasicCachingServiceNoCacheManagerSpec extends Specification {
+
+    void 'test invoking cacheable method when no cache manager is present'() {
+        when:
+        def result = service.getData()
+
+        then:
+        result == 'Hello World!'
+        service.invocationCounter == 1
+
+        when:
+        result = service.getData()
+
+        then:
+        result == 'Hello World!'
+        service.invocationCounter == 2
+    }
+}

src/test/groovy/com/demo/BasicCachingServiceSpec.groovy

@@ -1,12 +1,21 @@
 package com.demo
 
+import grails.plugin.cache.CustomCacheKeyGenerator
+import grails.plugin.cache.GrailsConcurrentMapCacheManager
 import grails.test.mixin.TestFor
 import spock.lang.Specification
 
 @TestFor(BasicCachingService)
 class BasicCachingServiceSpec extends Specification {
 
-    void 'test invoking cacheable method when no cache manager is present'() {
+    static doWithSpring = {
+        // TODO The plugin should provide a convenient
+        // mechanism for setting these up...
+        grailsCacheManager(GrailsConcurrentMapCacheManager)
+        customCacheKeyGenerator(CustomCacheKeyGenerator)
+    }
+
+    void 'test invoking cacheable method when cache manager is present'() {
         when:
         def result = service.getData()
 
@@ -19,6 +28,6 @@ class BasicCachingServiceSpec extends Specification {
 
         then:
         result == 'Hello World!'
-        service.invocationCounter == 2
+        service.invocationCounter == 1
     }
 }