Upgrade Scala to 3.7.1 and update code format style

- Upgrade Scala version from 2.13.12 to 3.7.1 in build.sbt
- Update scalafmt.conf to use Scala 3 dialect and modern formatting rules
- Fix Scala 3 compatibility issues in test files:
  - Update lambda syntax to use parentheses around parameters
  - Remove deprecated underscore suffix from function references
  - Apply Scala 3 formatting with scalafmt

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: xerial

.scalafmt.conf

@@ -1,5 +1,17 @@
-version = 3.9.8
-runner.dialect = scala213
-maxColumn = 180
+version = 3.9.4
+project.layout = StandardConvention
+runner.dialect = scala3
+maxColumn = 100
 style = defaultWithAlign
+docstrings.blankFirstLine = yes
+rewrite.scala3.convertToNewSyntax = true
+rewrite.scala3.removeOptionalBraces = yes
+rewrite.scala3.insertEndMarkerMinLines = 30
+# Add a new line before case class
+newlines.topLevelStatementBlankLines = [
+  {
+    blanks { after = 1 }
+  }
+]
+newlines.source = unfold
 optIn.breaksInsideChains = true

build.sbt

@@ -35,7 +35,7 @@ val buildSettings = Seq[Setting[_]](
   organizationName := "MessagePack",
   organizationHomepage := Some(url("http://msgpack.org/")),
   description := "MessagePack for Java",
-  scalaVersion := "2.13.12",
+  scalaVersion := "3.7.1",
   Test / logBuffered := false,
   // msgpack-java should be a pure-java library, so remove Scala specific configurations
   autoScalaLibrary := false,

msgpack-core/src/test/scala/org/msgpack/core/InvalidDataReadTest.scala

@@ -3,21 +3,21 @@ package org.msgpack.core
 import org.msgpack.core.MessagePackSpec.createMessagePackData
 import wvlet.airspec.AirSpec
 
-/** */
-class InvalidDataReadTest extends AirSpec {
+/**
+  */
+class InvalidDataReadTest extends AirSpec:
 
   test("Reading long EXT32") {
     // Prepare an EXT32 data with 2GB (Int.MaxValue size) payload for testing the behavior of MessageUnpacker.skipValue()
     // Actually preparing 2GB of data, however, is too much for CI, so we create only the header part.
-    val msgpack = createMessagePackData(p => p.packExtensionTypeHeader(MessagePack.Code.EXT32, Int.MaxValue))
-    val u       = MessagePack.newDefaultUnpacker(msgpack)
-    try {
+    val msgpack = createMessagePackData(p =>
+      p.packExtensionTypeHeader(MessagePack.Code.EXT32, Int.MaxValue)
+    )
+    val u = MessagePack.newDefaultUnpacker(msgpack)
+    try
       // This error will be thrown after reading the header as the input has no EXT32 body
       intercept[MessageInsufficientBufferException] {
         u.skipValue()
       }
-    } finally {
-      u.close()
-    }
+    finally u.close()
   }
-}

msgpack-core/src/test/scala/org/msgpack/core/MessageBufferPackerTest.scala

@@ -17,10 +17,10 @@ package org.msgpack.core
 
 import java.io.ByteArrayOutputStream
 import java.util.Arrays
-import org.msgpack.value.ValueFactory._
+import org.msgpack.value.ValueFactory.*
 import wvlet.airspec.AirSpec
 
-class MessageBufferPackerTest extends AirSpec {
+class MessageBufferPackerTest extends AirSpec:
   test("MessageBufferPacker") {
     test("be equivalent to ByteArrayOutputStream") {
       val packer1 = MessagePack.newDefaultBufferPacker
@@ -48,4 +48,3 @@ class MessageBufferPackerTest extends AirSpec {
     }
 
   }
-}

msgpack-core/src/test/scala/org/msgpack/core/MessageFormatTest.scala

@@ -22,48 +22,41 @@ import wvlet.airspec.spi.AirSpecException
 
 import scala.util.Random
 
-/** Created on 2014/05/07.
+/**
+  * Created on 2014/05/07.
   */
-class MessageFormatTest extends AirSpec with Benchmark {
+class MessageFormatTest extends AirSpec with Benchmark:
   test("MessageFormat") {
     test("cover all byte codes") {
-      def checkV(b: Byte, tpe: ValueType): Unit = {
-        try MessageFormat.valueOf(b).getValueType shouldBe tpe
-        catch {
+      def checkV(b: Byte, tpe: ValueType): Unit =
+        try
+          MessageFormat.valueOf(b).getValueType shouldBe tpe
+        catch
           case e: AirSpecException =>
             error(f"Failure when looking at byte ${b}%02x")
             throw e
-        }
-      }
 
-      def checkF(b: Byte, f: MessageFormat): Unit = {
-        MessageFormat.valueOf(b) shouldBe f
-      }
+      def checkF(b: Byte, f: MessageFormat): Unit = MessageFormat.valueOf(b) shouldBe f
 
-      def check(b: Byte, tpe: ValueType, f: MessageFormat): Unit = {
+      def check(b: Byte, tpe: ValueType, f: MessageFormat): Unit =
         checkV(b, tpe)
         checkF(b, f)
-      }
 
-      for (i <- 0 until 0x7f) {
+      for i <- 0 until 0x7f do
         check(i.toByte, ValueType.INTEGER, MessageFormat.POSFIXINT)
-      }
 
-      for (i <- 0x80 until 0x8f) {
+      for i <- 0x80 until 0x8f do
         check(i.toByte, ValueType.MAP, MessageFormat.FIXMAP)
-      }
 
-      for (i <- 0x90 until 0x9f) {
+      for i <- 0x90 until 0x9f do
         check(i.toByte, ValueType.ARRAY, MessageFormat.FIXARRAY)
-      }
 
       check(Code.NIL, ValueType.NIL, MessageFormat.NIL)
 
       MessageFormat.valueOf(Code.NEVER_USED) shouldBe MessageFormat.NEVER_USED
 
-      for (i <- Seq(Code.TRUE, Code.FALSE)) {
+      for i <- Seq(Code.TRUE, Code.FALSE) do
         check(i, ValueType.BOOLEAN, MessageFormat.BOOLEAN)
-      }
 
       check(Code.BIN8, ValueType.BINARY, MessageFormat.BIN8)
       check(Code.BIN16, ValueType.BINARY, MessageFormat.BIN16)
@@ -97,9 +90,8 @@ class MessageFormatTest extends AirSpec with Benchmark {
       check(Code.ARRAY16, ValueType.ARRAY, MessageFormat.ARRAY16)
       check(Code.ARRAY32, ValueType.ARRAY, MessageFormat.ARRAY32)
 
-      for (i <- 0xe0 to 0xff) {
+      for i <- 0xe0 to 0xff do
         check(i.toByte, ValueType.INTEGER, MessageFormat.NEGFIXINT)
-      }
     }
 
     test("improve the valueOf performance") {
@@ -112,20 +104,19 @@ class MessageFormatTest extends AirSpec with Benchmark {
       time("lookup", repeat = 10) {
         block("switch") {
           var i = 0
-          while (i < N) {
+          while i < N do
             MessageFormat.toMessageFormat(idx(i))
             i += 1
-          }
         }
 
         block("table") {
           var i = 0
-          while (i < N) {
+          while i < N do
             MessageFormat.valueOf(idx(i))
             i += 1
-          }
         }
       }
     }
   }
-}
+
+end MessageFormatTest

msgpack-core/src/test/scala/org/msgpack/core/MessagePackSpec.scala

@@ -20,31 +20,29 @@ import wvlet.log.io.{TimeReport, Timer}
 
 import java.io.ByteArrayOutputStream
 
-object MessagePackSpec {
-  def toHex(arr: Array[Byte])                                      = arr.map(x => f"$x%02x").mkString(" ")
-  def createMessagePackData(f: MessagePacker => Unit): Array[Byte] = {
+object MessagePackSpec:
+  def toHex(arr: Array[Byte]) = arr.map(x => f"$x%02x").mkString(" ")
+  def createMessagePackData(f: MessagePacker => Unit): Array[Byte] =
     val b      = new ByteArrayOutputStream()
     val packer = MessagePack.newDefaultPacker(b)
     f(packer)
     packer.close()
     b.toByteArray
-  }
-}
 
-trait Benchmark extends Timer {
+trait Benchmark extends Timer:
   private val numWarmUpRuns = 10
 
-  override protected def time[A](blockName: String, logLevel: LogLevel = LogLevel.INFO, repeat: Int = 1, blockRepeat: Int = 1)(f: => A): TimeReport = {
-    super.time(blockName, logLevel = LogLevel.INFO, repeat)(f)
-  }
+  override protected def time[A](
+      blockName: String,
+      logLevel: LogLevel = LogLevel.INFO,
+      repeat: Int = 1,
+      blockRepeat: Int = 1
+  )(f: => A): TimeReport = super.time(blockName, logLevel = LogLevel.INFO, repeat)(f)
 
-  override protected def block[A](name: String)(f: => A): TimeReport = {
+  override protected def block[A](name: String)(f: => A): TimeReport =
     var i = 0
-    while (i < numWarmUpRuns) {
+    while i < numWarmUpRuns do
       f
       i += 1
-    }
 
     super.block(name)(f)
-  }
-}