[SPARK-14025][STREAMING][WEBUI] Fix streaming job descriptions on the event timeline

## What changes were proposed in this pull request?

Removed the extra `<a href=...>...</a>` for each streaming job's description on the event timeline.

### [Before]
![before](https://cloud.githubusercontent.com/assets/15843379/13898653/0a6c1838-ee13-11e5-9761-14bb7b114c13.png)

### [After]
![after](https://cloud.githubusercontent.com/assets/15843379/13898650/012b8808-ee13-11e5-92a6-64aff0799c83.png)

## How was this patch tested?

test suits, manual checks (see screenshots above)

Author: Liwei Lin <proflin.me@gmail.com>
Author: proflin <proflin.me@gmail.com>

Closes #11845 from lw-lin/description-event-line.

1 files changed, 65 insertions, 9 deletions

diff --git a/core/src/test/scala/org/apache/spark/ui/UIUtilsSuite.scala b/core/src/test/scala/org/apache/spark/ui/UIUtilsSuite.scala
index bc8a5d494d..58beaf103c 100644
--- a/core/src/test/scala/org/apache/spark/ui/UIUtilsSuite.scala
+++ b/core/src/test/scala/org/apache/spark/ui/UIUtilsSuite.scala
@@ -17,43 +17,95 @@
 
 package org.apache.spark.ui
 
-import scala.xml.Elem
+import scala.xml.{Node, Text}
 
 import org.apache.spark.SparkFunSuite
 
 class UIUtilsSuite extends SparkFunSuite {
   import UIUtils._
 
-  test("makeDescription") {
+  test("makeDescription(plainText = false)") {
     verify(
       """test <a href="/link"> text </a>""",
       <span class="description-input">test <a href="/link"> text </a></span>,
-      "Correctly formatted text with only anchors and relative links should generate HTML"
+      "Correctly formatted text with only anchors and relative links should generate HTML",
+      plainText = false
     )
 
     verify(
       """test <a href="/link" text </a>""",
       <span class="description-input">{"""test <a href="/link" text </a>"""}</span>,
-      "Badly formatted text should make the description be treated as a streaming instead of HTML"
+      "Badly formatted text should make the description be treated as a string instead of HTML",
+      plainText = false
     )
 
     verify(
       """test <a href="link"> text </a>""",
       <span class="description-input">{"""test <a href="link"> text </a>"""}</span>,
-      "Non-relative links should make the description be treated as a string instead of HTML"
+      "Non-relative links should make the description be treated as a string instead of HTML",
+      plainText = false
     )
 
     verify(
       """test<a><img></img></a>""",
       <span class="description-input">{"""test<a><img></img></a>"""}</span>,
-      "Non-anchor elements should make the description be treated as a string instead of HTML"
+      "Non-anchor elements should make the description be treated as a string instead of HTML",
+      plainText = false
     )
 
     verify(
       """test <a href="/link"> text </a>""",
       <span class="description-input">test <a href="base/link"> text </a></span>,
       baseUrl = "base",
-      errorMsg = "Base URL should be prepended to html links"
+      errorMsg = "Base URL should be prepended to html links",
+      plainText = false
+    )
+  }
+
+  test("makeDescription(plainText = true)") {
+    verify(
+      """test <a href="/link"> text </a>""",
+      Text("test  text "),
+      "Correctly formatted text with only anchors and relative links should generate a string " +
+      "without any html tags",
+      plainText = true
+    )
+
+    verify(
+      """test <a href="/link"> text1 </a> <a href="/link"> text2 </a>""",
+      Text("test  text1   text2 "),
+      "Correctly formatted text with multiple anchors and relative links should generate a " +
+      "string without any html tags",
+      plainText = true
+    )
+
+    verify(
+      """test <a href="/link"><span> text </span></a>""",
+      Text("test  text "),
+      "Correctly formatted text with nested anchors and relative links and/or spans should " +
+      "generate a string without any html tags",
+      plainText = true
+    )
+
+    verify(
+      """test <a href="/link" text </a>""",
+      Text("""test <a href="/link" text </a>"""),
+      "Badly formatted text should make the description be as the same as the original text",
+      plainText = true
+    )
+
+    verify(
+      """test <a href="link"> text </a>""",
+      Text("""test <a href="link"> text </a>"""),
+      "Non-relative links should make the description be as the same as the original text",
+      plainText = true
+    )
+
+    verify(
+      """test<a><img></img></a>""",
+      Text("""test<a><img></img></a>"""),
+      "Non-anchor elements should make the description be as the same as the original text",
+      plainText = true
     )
   }
 
@@ -82,8 +134,12 @@ class UIUtilsSuite extends SparkFunSuite {
   }
 
   private def verify(
-      desc: String, expected: Elem, errorMsg: String = "", baseUrl: String = ""): Unit = {
-    val generated = makeDescription(desc, baseUrl)
+      desc: String,
+      expected: Node,
+      errorMsg: String = "",
+      baseUrl: String = "",
+      plainText: Boolean): Unit = {
+    val generated = makeDescription(desc, baseUrl, plainText)
     assert(generated.sameElements(expected),
       s"\n$errorMsg\n\nExpected:\n$expected\nGenerated:\n$generated")
   }