[SPARK-47723][CORE][TESTS] Introduce a tool that can sort alphabetically enumeration field in LogEntry automatically

common/utils/src/test/scala/org/apache/spark/util/LogKeySuite.scala

@@ -17,17 +17,80 @@
 
 package org.apache.spark.util
 
+import java.nio.charset.StandardCharsets
+import java.nio.file.{Files, Path}
+import java.util.{ArrayList => JList}
+
+import scala.jdk.CollectionConverters._
+
+import org.apache.commons.io.FileUtils
 import org.scalatest.funsuite.AnyFunSuite // scalastyle:ignore funsuite
 
 import org.apache.spark.internal.{Logging, LogKey}
+import org.apache.spark.internal.LogKey.LogKey
 
+// scalastyle:off line.size.limit
+/**
+ * To re-generate the LogKey class file, run:
+ * {{{
+ *   SPARK_GENERATE_GOLDEN_FILES=1 build/sbt "common-utils/testOnly org.apache.spark.util.LogKeySuite"
+ * }}}
+ */
+// scalastyle:on line.size.limit
 class LogKeySuite
     extends AnyFunSuite // scalastyle:ignore funsuite
     with Logging {
 
-  test("LogKey enumeration fields must be sorted alphabetically") {
-    val keys = LogKey.values.toSeq
-    assert(keys === keys.sortBy(_.toString),
-      "LogKey enumeration fields must be sorted alphabetically")
+  /**
+   * Get a Path relative to the root project. It is assumed that a spark home is set.
+   */
+  protected final def getWorkspaceFilePath(first: String, more: String*): Path = {
+    if (!(sys.props.contains("spark.test.home") || sys.env.contains("SPARK_HOME"))) {
+      fail("spark.test.home or SPARK_HOME is not set.")
+    }
+    val sparkHome = sys.props.getOrElse("spark.test.home", sys.env("SPARK_HOME"))
+    java.nio.file.Paths.get(sparkHome, first +: more: _*)
+  }
+
+  private val regenerateGoldenFiles: Boolean = System.getenv("SPARK_GENERATE_GOLDEN_FILES") == "1"
+
+  private val logKeyFilePath = getWorkspaceFilePath("common", "utils", "src", "main", "scala",
+    "org", "apache", "spark", "internal", "LogKey.scala")
+
+  // regenerate the file `LogKey.scala` with its enumeration fields sorted alphabetically
+  private def regenerateLogKeyFile(
+      originalKeys: Seq[LogKey], sortedKeys: Seq[LogKey]): Unit = {
+    if (originalKeys != sortedKeys) {
+      val logKeyFile = logKeyFilePath.toFile
+      logInfo(s"Regenerating LogKey file $logKeyFile")
+      val originalContents = FileUtils.readLines(logKeyFile, StandardCharsets.UTF_8)
+      val sortedContents = new JList[String]()
+      var firstMatch = false
+      originalContents.asScala.foreach { line =>
+        if (line.trim.startsWith("val ") && line.trim.endsWith(" = Value")) {
+          if (!firstMatch) {
+            sortedKeys.foreach { logKey =>
+              sortedContents.add(s"  val ${logKey.toString} = Value")
+            }
+            firstMatch = true
+          }
+        } else {
+          sortedContents.add(line)
+        }
+      }
+      Files.delete(logKeyFile.toPath)
+      FileUtils.writeLines(logKeyFile, StandardCharsets.UTF_8.name(), sortedContents)
+    }
+  }
+
+  test("LogKey enumeration fields are correctly sorted") {
+    val originalKeys = LogKey.values.toSeq
+    val sortedKeys = originalKeys.sortBy(_.toString)
+    if (regenerateGoldenFiles) {
+      regenerateLogKeyFile(originalKeys, sortedKeys)
+    } else {
+      assert(originalKeys === sortedKeys,
+        "LogKey enumeration fields must be sorted alphabetically")
+    }
   }
 }