[Spark] Use Spark conf to control special char injection in paths (#3616

)

#### Which Delta project/connector is this regarding?

- [X] Spark
- [ ] Standalone
- [ ] Flink
- [ ] Kernel
- [ ] Other (fill in here)

## Description

Use a static Spark config to select the prefix that will be used for
Parquet and DV files. This is a follow-up from commit 82f7971.

## How was this patch tested?

Test-only changes.

## Does this PR introduce _any_ user-facing changes?

No.

spark/src/main/scala/org/apache/spark/sql/delta/actions/DeletionVectorDescriptor.scala

@@ -21,6 +21,7 @@ import java.net.URI
 import java.util.{Base64, UUID}
 
 import org.apache.spark.sql.delta.DeltaErrors
+import org.apache.spark.sql.delta.sources.DeltaSQLConf
 import org.apache.spark.sql.delta.util.{Codec, DeltaEncoder, JsonUtils}
 import com.fasterxml.jackson.annotation.JsonIgnore
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize
@@ -29,6 +30,7 @@ import org.apache.hadoop.fs.Path
 import org.apache.spark.paths.SparkPath
 import org.apache.spark.sql.{Column, Encoder}
 import org.apache.spark.sql.functions.{concat, lit, when}
+import org.apache.spark.sql.internal.SQLConf
 import org.apache.spark.sql.types._
 import org.apache.spark.util.Utils
 
@@ -202,7 +204,8 @@ case class DeletionVectorDescriptor(
 object DeletionVectorDescriptor {
 
   /** Prefix that is used in all file names generated by deletion vector store. */
-  val DELETION_VECTOR_FILE_NAME_PREFIX = if (Utils.isTesting) "test%dv%prefix-" else ""
+  val DELETION_VECTOR_FILE_NAME_PREFIX = SQLConf.get.getConf(DeltaSQLConf.TEST_DV_NAME_PREFIX)
+
   /** String that is used in all file names generated by deletion vector store */
   val DELETION_VECTOR_FILE_NAME_CORE = DELETION_VECTOR_FILE_NAME_PREFIX + "deletion_vector"
 

spark/src/main/scala/org/apache/spark/sql/delta/files/DelayedCommitProtocol.scala

@@ -35,6 +35,7 @@ import org.apache.spark.internal.io.FileCommitProtocol.TaskCommitMessage
 import org.apache.spark.sql.catalyst.expressions.Cast
 import org.apache.spark.sql.delta.files.DeltaFileFormatWriter.PartitionedTaskAttemptContextImpl
 import org.apache.spark.sql.delta.sources.DeltaSQLConf
+import org.apache.spark.sql.internal.SQLConf
 import org.apache.spark.sql.types.{DataType, StringType, TimestampType}
 import org.apache.spark.util.Utils
 
@@ -110,7 +111,7 @@ class DelayedCommitProtocol(
   }
 
   /** Prefix added in testing mode to all filenames to test special chars that need URL-encoding. */
-  val FILE_NAME_PREFIX = if (Utils.isTesting) "test%file%prefix-" else ""
+  val FILE_NAME_PREFIX = SQLConf.get.getConf(DeltaSQLConf.TEST_FILE_NAME_PREFIX)
 
   protected def getFileName(
       taskContext: TaskAttemptContext,

spark/src/main/scala/org/apache/spark/sql/delta/sources/DeltaSQLConf.scala

@@ -2026,6 +2026,20 @@ trait DeltaSQLConfBase {
       .booleanConf
       .createWithDefault(Utils.isTesting)
 
+  val TEST_FILE_NAME_PREFIX =
+    buildStaticConf("testOnly.dataFileNamePrefix")
+      .internal()
+      .doc("[TEST_ONLY]: The prefix to use for the names of all Parquet data files.")
+      .stringConf
+      .createWithDefault(if (Utils.isTesting) "test%file%prefix-" else "")
+
+  val TEST_DV_NAME_PREFIX =
+    buildStaticConf("testOnly.dvFileNamePrefix")
+      .internal()
+      .doc("[TEST_ONLY]: The prefix to use for the names of all Deletion Vector files.")
+      .stringConf
+      .createWithDefault(if (Utils.isTesting) "test%dv%prefix-" else "")
+
   ///////////
   // UTC TIMESTAMP PARTITION VALUES
   ///////////////////