From 710a68cec27a94c2df10d8b4022a755a94a5443b Mon Sep 17 00:00:00 2001
From: Kazuaki Ishizaki <ishizaki@jp.ibm.com>
Date: Sun, 8 Apr 2018 20:26:31 +0200
Subject: [PATCH] [SPARK-23892][TEST] Improve converge and fix lint error in
 UTF8String-related tests

## What changes were proposed in this pull request?

This PR improves test coverage in `UTF8StringSuite` and code efficiency in `UTF8StringPropertyCheckSuite`.

This PR also fixes lint-java issue in `UTF8StringSuite` reported at [here](https://github.com/apache/spark/pull/20995#issuecomment-379325527)

```[ERROR] src/test/java/org/apache/spark/unsafe/types/UTF8StringSuite.java:[28,8] (imports) UnusedImports: Unused import - org.apache.spark.unsafe.Platform.```

## How was this patch tested?

Existing UT

Author: Kazuaki Ishizaki <ishizaki@jp.ibm.com>

Closes #21000 from kiszk/SPARK-23892.
---
 .../java/org/apache/spark/unsafe/types/UTF8StringSuite.java  | 5 ++---
 .../spark/unsafe/types/UTF8StringPropertyCheckSuite.scala    | 2 +-
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/common/unsafe/src/test/java/org/apache/spark/unsafe/types/UTF8StringSuite.java b/common/unsafe/src/test/java/org/apache/spark/unsafe/types/UTF8StringSuite.java
index 2c08535a16..42dda30480 100644
--- a/common/unsafe/src/test/java/org/apache/spark/unsafe/types/UTF8StringSuite.java
+++ b/common/unsafe/src/test/java/org/apache/spark/unsafe/types/UTF8StringSuite.java
@@ -25,7 +25,6 @@ import java.nio.charset.StandardCharsets;
 import java.util.*;
 
 import com.google.common.collect.ImmutableMap;
-import org.apache.spark.unsafe.Platform;
 import org.apache.spark.unsafe.memory.ByteArrayMemoryBlock;
 import org.apache.spark.unsafe.memory.OnHeapMemoryBlock;
 import org.junit.Test;
@@ -53,8 +52,8 @@ public class UTF8StringSuite {
 
     assertTrue(s1.contains(s2));
     assertTrue(s2.contains(s1));
-    assertTrue(s1.startsWith(s1));
-    assertTrue(s1.endsWith(s1));
+    assertTrue(s1.startsWith(s2));
+    assertTrue(s1.endsWith(s2));
   }
 
   @Test
diff --git a/common/unsafe/src/test/scala/org/apache/spark/unsafe/types/UTF8StringPropertyCheckSuite.scala b/common/unsafe/src/test/scala/org/apache/spark/unsafe/types/UTF8StringPropertyCheckSuite.scala
index 62d4176d00..48004e812a 100644
--- a/common/unsafe/src/test/scala/org/apache/spark/unsafe/types/UTF8StringPropertyCheckSuite.scala
+++ b/common/unsafe/src/test/scala/org/apache/spark/unsafe/types/UTF8StringPropertyCheckSuite.scala
@@ -164,7 +164,7 @@ class UTF8StringPropertyCheckSuite extends FunSuite with GeneratorDrivenProperty
     def padding(origin: String, pad: String, length: Int, isLPad: Boolean): String = {
       if (length <= 0) return ""
       if (length <= origin.length) {
-        if (length <= 0) "" else origin.substring(0, length)
+        origin.substring(0, length)
       } else {
         if (pad.length == 0) return origin
         val toPad = length - origin.length