diff --git a/core/src/main/scala/org/apache/spark/executor/TaskMetrics.scala b/core/src/main/scala/org/apache/spark/executor/TaskMetrics.scala
index 9849d1ed87f69..493abcc727f9c 100644
--- a/core/src/main/scala/org/apache/spark/executor/TaskMetrics.scala
+++ b/core/src/main/scala/org/apache/spark/executor/TaskMetrics.scala
@@ -194,7 +194,7 @@ class TaskMetrics extends Serializable {
   /**
    * Aggregates shuffle read metrics for all registered dependencies into shuffleReadMetrics.
    */
-  private[spark] def updateShuffleReadMetrics() = synchronized {
+  private[spark] def updateShuffleReadMetrics(): Unit = synchronized {
     val merged = new ShuffleReadMetrics()
     for (depMetrics <- depsShuffleReadMetrics) {
       merged.incFetchWaitTime(depMetrics.fetchWaitTime)
@@ -206,7 +206,7 @@ class TaskMetrics extends Serializable {
     _shuffleReadMetrics = Some(merged)
   }
 
-  private[spark] def updateInputMetrics() = synchronized {
+  private[spark] def updateInputMetrics(): Unit = synchronized {
     inputMetrics.foreach(_.updateBytesRead())
   }
 }
diff --git a/core/src/test/scala/org/apache/spark/storage/BlockObjectWriterSuite.scala b/core/src/test/scala/org/apache/spark/storage/BlockObjectWriterSuite.scala
index dc937d49edee3..7ec3559bb7d78 100644
--- a/core/src/test/scala/org/apache/spark/storage/BlockObjectWriterSuite.scala
+++ b/core/src/test/scala/org/apache/spark/storage/BlockObjectWriterSuite.scala
@@ -32,7 +32,7 @@ class BlockObjectWriterSuite extends FunSuite {
 
     writer.write(Long.box(20))
     // Record metrics update on every write
-    assert(writeMetrics.recordsWritten == 1)
+    assert(writeMetrics.recordsWritten === 1)
     // Metrics don't update on every write
     assert(writeMetrics.shuffleBytesWritten == 0)
     // After 32 writes, metrics should update
@@ -41,7 +41,7 @@ class BlockObjectWriterSuite extends FunSuite {
       writer.write(Long.box(i))
     }
     assert(writeMetrics.shuffleBytesWritten > 0)
-    assert(writeMetrics.recordsWritten == 33)
+    assert(writeMetrics.recordsWritten === 33)
     writer.commitAndClose()
     assert(file.length() == writeMetrics.shuffleBytesWritten)
   }
@@ -55,7 +55,7 @@ class BlockObjectWriterSuite extends FunSuite {
 
     writer.write(Long.box(20))
     // Record metrics update on every write
-    assert(writeMetrics.recordsWritten == 1)
+    assert(writeMetrics.recordsWritten === 1)
     // Metrics don't update on every write
     assert(writeMetrics.shuffleBytesWritten == 0)
     // After 32 writes, metrics should update
@@ -64,7 +64,7 @@ class BlockObjectWriterSuite extends FunSuite {
       writer.write(Long.box(i))
     }
     assert(writeMetrics.shuffleBytesWritten > 0)
-    assert(writeMetrics.recordsWritten == 33)
+    assert(writeMetrics.recordsWritten === 33)
     writer.revertPartialWritesAndClose()
     assert(writeMetrics.shuffleBytesWritten == 0)
     assert(writeMetrics.recordsWritten == 0)
diff --git a/core/src/test/scala/org/apache/spark/util/JsonProtocolSuite.scala b/core/src/test/scala/org/apache/spark/util/JsonProtocolSuite.scala
index 86fe1005f1f57..7531abb82a16d 100644
--- a/core/src/test/scala/org/apache/spark/util/JsonProtocolSuite.scala
+++ b/core/src/test/scala/org/apache/spark/util/JsonProtocolSuite.scala
@@ -684,7 +684,7 @@ class JsonProtocolSuite extends FunSuite {
     if (hasHadoopInput) {
       val inputMetrics = new InputMetrics(DataReadMethod.Hadoop)
       inputMetrics.addBytesRead(d + e + f)
-      inputMetrics.addRecordsRead(if(hasRecords) (d + e + f) / 100 else -1)
+      inputMetrics.addRecordsRead(if (hasRecords) (d + e + f) / 100 else -1)
       t.setInputMetrics(Some(inputMetrics))
     } else {
       val sr = new ShuffleReadMetrics
@@ -692,19 +692,19 @@ class JsonProtocolSuite extends FunSuite {
       sr.incLocalBlocksFetched(e)
       sr.incFetchWaitTime(a + d)
       sr.incRemoteBlocksFetched(f)
-      sr.recordsRead = if(hasRecords) (b + d) / 100 else -1
+      sr.recordsRead = if (hasRecords) (b + d) / 100 else -1
       t.setShuffleReadMetrics(Some(sr))
     }
     if (hasOutput) {
       val outputMetrics = new OutputMetrics(DataWriteMethod.Hadoop)
       outputMetrics.setBytesWritten(a + b + c)
-      outputMetrics.recordsWritten = if(hasRecords) (a + b + c)/100 else -1
+      outputMetrics.recordsWritten = if (hasRecords) (a + b + c)/100 else -1
       t.outputMetrics = Some(outputMetrics)
     } else {
       val sw = new ShuffleWriteMetrics
       sw.incShuffleBytesWritten(a + b + c)
       sw.incShuffleWriteTime(b + c + d)
-      sw.recordsWritten = if(hasRecords) (a + b + c) / 100 else -1
+      sw.recordsWritten = if (hasRecords) (a + b + c) / 100 else -1
       t.shuffleWriteMetrics = Some(sw)
     }
     // Make at most 6 blocks