cmd/clean: Don't clean if cache is empty

cmd/hvm/clean.go

@@ -44,6 +44,17 @@ func init() {
 // clean cleans the cache, excluding the version installed with the "install"
 // command.
 func clean() error {
+
+	cacheSize, err := getCacheSize()
+	if err != nil {
+		return err
+	}
+
+	if cacheSize == 0 {
+		fmt.Println("The cache is already empty.")
+		return nil
+	}
+
 	fmt.Println("This will delete cached versions of the Hugo executable.")
 
 	var r string

cmd/hvm/testscripts/clean.txt

@@ -7,13 +7,17 @@
 [windows] env LocalAppData=cache
 [windows] env AppData=config
 
-# Test
+# Test 1: cache is not empty
 stdin input.txt
 exec hvm clean
 stdout 'This will delete cached versions of the Hugo executable.'
 stdout 'Are you sure you want to clean the cache\? \(y/N\): '
 stdout 'Cache cleaned.'
 
+# Test 2: cache is empty
+exec hvm clean
+stdout 'The cache is already empty.'
+
 # Files
 -- input.txt --
 y