Fix test which doesn't seem to be in reality

Author: HeartSaVioR

sql/core/src/main/scala/org/apache/spark/sql/execution/streaming/FileStreamSinkLog.scala

@@ -104,6 +104,8 @@ class FileStreamSinkLog(
 
 object FileStreamSinkLog {
   val VERSION = 1
+  // TODO: This action hasn't been used from the introduction. We should just remove this.
+  // TODO: We can remove the field "action" as well, ignoring "action" in existing metadata log.
   val DELETE_ACTION = "delete"
   val ADD_ACTION = "add"
 }

sql/core/src/test/resources/structured-streaming/file-sink-log-version-2.1.0/8

@@ -1,3 +1,2 @@
 v1
 {"path":"/a/b/8","size":800,"isDir":false,"modificationTime":800,"blockReplication":1,"blockSize":100,"action":"add"}
-{"path":"/a/b/0","size":100,"isDir":false,"modificationTime":100,"blockReplication":1,"blockSize":100,"action":"delete"}

sql/core/src/test/scala/org/apache/spark/sql/execution/streaming/FileStreamSinkLogSuite.scala

@@ -227,11 +227,9 @@ class FileStreamSinkLogSuite extends SparkFunSuite with SharedSparkSession {
     }
   }
 
-  // FIXME: sigh, we should really remove ACTION which is always ADD_ACTION...
-  //  DELETE_ACTION exists "hypothetically". It prevents streamlining of handling entries.
-  ignore("read Spark 2.1.0 log format") {
+  test("read Spark 2.1.0 log format") {
     assert(readFromResource("file-sink-log-version-2.1.0") === Seq(
-      // SinkFileStatus("/a/b/0", 100, false, 100, 1, 100, FileStreamSinkLog.ADD_ACTION), -> deleted
+      SinkFileStatus("/a/b/0", 1, false, 1, 1, 100, FileStreamSinkLog.ADD_ACTION),
       SinkFileStatus("/a/b/1", 100, false, 100, 1, 100, FileStreamSinkLog.ADD_ACTION),
       SinkFileStatus("/a/b/2", 200, false, 200, 1, 100, FileStreamSinkLog.ADD_ACTION),
       SinkFileStatus("/a/b/3", 300, false, 300, 1, 100, FileStreamSinkLog.ADD_ACTION),