Fail if configuration-cache is enabled without dependencies cache

Fixes #61

README.md

@@ -144,6 +144,8 @@ The distributions cache is simple and can't be configured further.
 The dependencies and configuration cache will compute a cache key in a best effort manner.
 Keep reading to learn how to better control how they work.
 
+Note that enabling configuration cache without thee dependencies cache is not permitted, since a hit in the configuration cache assumes that dependencies are already present in the local dependencies cache.
+
 ### Configuring the dependencies and configuration caches
 
 Both the dependencies and configuration caches use the same default configuration:

src/cache-configuration.ts

@@ -6,7 +6,11 @@ import * as cache from '@actions/cache'
 
 import * as crypto from './crypto-utils'
 
-import {inputCacheKeyGlobs, tryDeleteFiles} from './cache-dependencies'
+import {
+    inputCacheKeyGlobs,
+    tryDeleteFiles,
+    isDependenciesCacheDisabled
+} from './cache-dependencies'
 
 const CONFIGURATION_CACHE_PATH = 'CONFIGURATION_CACHE_PATH'
 const CONFIGURATION_CACHE_KEY = 'CONFIGURATION_CACHE_KEY'
@@ -17,6 +21,12 @@ export async function restoreCachedConfiguration(
 ): Promise<void> {
     if (isConfigurationCacheDisabled()) return
 
+    if (isDependenciesCacheDisabled()) {
+        throw new Error(
+            `Must enable dependencies-cache when configuration-cache is enabled`
+        )
+    }
+
     const cachePath = path.resolve(rootDir, '.gradle/configuration-cache')
     if (fs.existsSync(cachePath)) return
     core.saveState(CONFIGURATION_CACHE_PATH, cachePath)

src/cache-dependencies.ts

@@ -102,7 +102,7 @@ export function tryDeleteFiles(filePaths: string[]): boolean {
     return !failure
 }
 
-function isDependenciesCacheDisabled(): boolean {
+export function isDependenciesCacheDisabled(): boolean {
     return !core.getBooleanInput('dependencies-cache-enabled')
 }