Report the cache as disabled when Gradle User Home exists

Fixes gradle#434

.github/workflows/demo-job-summary.yml

@@ -41,3 +41,25 @@ jobs:
       working-directory: .github/workflow-samples/groovy-dsl
       continue-on-error: true
       run: ./gradlew not-a-real-task
+
+  pre-existing-gradle-home:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout sources
+      uses: actions/checkout@v3
+    - name: Build distribution
+      shell: bash
+      run: |
+        npm install
+        npm run build
+    - name: Pre-create Gradle User Home
+      shell: bash
+      run: |
+        mkdir ~/.gradle
+        mkdir ~/.gradle/caches
+        touch ~/.gradle/caches/dummy.txt
+    - name: Setup Gradle
+      uses: ./
+    - name: Run build
+      working-directory: .github/workflow-samples/groovy-dsl
+      run: ./gradlew assemble

src/cache-reporting.ts

@@ -10,14 +10,15 @@ export class CacheListener {
     cacheReadOnly = false
     cacheWriteOnly = false
     cacheDisabled = false
+    cacheDisabledReason = 'disabled'
 
     get fullyRestored(): boolean {
         return this.cacheEntries.every(x => !x.wasRequestedButNotRestored())
     }
 
     get cacheStatus(): string {
         if (!cache.isFeatureAvailable()) return 'not available'
-        if (this.cacheDisabled) return 'disabled'
+        if (this.cacheDisabled) return this.cacheDisabledReason
         if (this.cacheWriteOnly) return 'write-only'
         if (this.cacheReadOnly) return 'read-only'
         return 'enabled'

src/caches.ts

@@ -29,6 +29,8 @@ export async function restore(gradleUserHome: string, cacheListener: CacheListen
         core.info('Gradle User Home already exists: will not restore from cache.')
         // Initialize pre-existing Gradle User Home.
         gradleStateCache.init()
+        cacheListener.cacheDisabled = true
+        cacheListener.cacheDisabledReason = 'disabled due to pre-existing Gradle User Home'
         return
     }