diff --git a/scala/build.sbt b/scala/build.sbt
index 6710bb4..9972b7f 100644
--- a/scala/build.sbt
+++ b/scala/build.sbt
@@ -2,5 +2,6 @@ lazy val root = (project in file("."))
   .settings(
     name := "algo-scala",
     version := "1.0",
-    scalaVersion := "2.12.8"
+    scalaVersion := "2.12.8",
+    libraryDependencies += "org.scalatest" %% "scalatest" % "3.0.5" % "test"
   )
diff --git a/scala/src/main/scala/ch05_array/ArrayDemo.scala b/scala/src/main/scala/ch05_array/ArrayDemo.scala
new file mode 100644
index 0000000..73b5e7d
--- /dev/null
+++ b/scala/src/main/scala/ch05_array/ArrayDemo.scala
@@ -0,0 +1,53 @@
+package ch05_array
+
+class ArrayDemo(capacity: Int) {
+
+  var data: Array[Char] = new Array[Char](capacity)
+  var length: Int = 0
+
+  def find(index: Int): Char = {
+    if (index < 0 || index > length) {
+      return 0.toChar
+    }
+    data(index)
+  }
+
+  def insert(index: Int, value: Char): Boolean = {
+    if (length == capacity) {
+      return false
+    }
+
+    if (index < 0 || index >= capacity) {
+      return false
+    }
+
+    for (i <- length until index by -1) {
+      data(i) = data(i - 1)
+    }
+    data(index) = value
+    length += 1
+
+    true
+  }
+
+  def delete(index: Int): Char = {
+    if (length == 0) {
+      throw new IllegalStateException("array is empty")
+    }
+    if (index >= length) {
+      throw new IllegalStateException("index out of range, current data length is " + length)
+    }
+    val result = data(index)
+    for (i <- index until length-1) {
+      data(i) = data(i + 1)
+    }
+
+    length -= 1
+    result
+  }
+
+  def print: String = {
+    data.subSequence(0, length).toString
+  }
+
+}
diff --git a/scala/src/main/scala/11_sorts/Sorts.scala b/scala/src/main/scala/ch11_sorts/Sorts.scala
similarity index 95%
rename from scala/src/main/scala/11_sorts/Sorts.scala
rename to scala/src/main/scala/ch11_sorts/Sorts.scala
index dfce2d7..bf110d3 100644
--- a/scala/src/main/scala/11_sorts/Sorts.scala
+++ b/scala/src/main/scala/ch11_sorts/Sorts.scala
@@ -1,4 +1,6 @@
-import scala.util.control.Breaks._
+package ch11_sorts
+
+import scala.util.control.Breaks.{break, breakable}
 
 /**
   * 冒泡排序、插入排序、选择排序
diff --git a/scala/src/main/scala/15_bsearch/BSearch.scala b/scala/src/main/scala/ch15_bsearch/BSearch.scala
similarity index 95%
rename from scala/src/main/scala/15_bsearch/BSearch.scala
rename to scala/src/main/scala/ch15_bsearch/BSearch.scala
index 0c8d0b4..2165938 100644
--- a/scala/src/main/scala/15_bsearch/BSearch.scala
+++ b/scala/src/main/scala/ch15_bsearch/BSearch.scala
@@ -1,3 +1,5 @@
+package ch15_bsearch
+
 object BSearch {
     def search(nums: Array[Int], target: Int): Int = {
         var low = 0
@@ -12,7 +14,7 @@ object BSearch {
                 return mid
             }
         }
-        
+
         return -1
     }
 }
diff --git a/scala/src/main/scala/15_bsearch/BSearchRecursive.scala b/scala/src/main/scala/ch15_bsearch/BSearchRecursive.scala
similarity index 85%
rename from scala/src/main/scala/15_bsearch/BSearchRecursive.scala
rename to scala/src/main/scala/ch15_bsearch/BSearchRecursive.scala
index b14a706..ca7befc 100644
--- a/scala/src/main/scala/15_bsearch/BSearchRecursive.scala
+++ b/scala/src/main/scala/ch15_bsearch/BSearchRecursive.scala
@@ -1,20 +1,22 @@
+package ch15_bsearch
+
 object BSearchRecursive {
     def search(nums: Array[Int], target: Int): Int = {
         return searchInternal(nums, target, 0, nums.length - 1)
     }
-    
+
     def searchInternal(nums:Array[Int], target: Int, low: Int, high: Int): Int = {
         if(low <= high){
             val mid = low + ((high - low) >> 2)
             if(nums(mid) > target){
                 searchInternal(nums, target, low, mid - 1)
-            } else if (nums(mid) < target){                
+            } else if (nums(mid) < target){
                 searchInternal(nums, target, mid + 1, high)
             } else {
                 return mid
             }
         }else{
-            return -1    
+            return -1
         }
     }
 }
diff --git a/scala/src/test/scala/ch05_array/ArrayDemoSpec.scala b/scala/src/test/scala/ch05_array/ArrayDemoSpec.scala
new file mode 100644
index 0000000..98691ba
--- /dev/null
+++ b/scala/src/test/scala/ch05_array/ArrayDemoSpec.scala
@@ -0,0 +1,67 @@
+package ch05_array
+
+import org.scalatest.{FlatSpec, Matchers}
+
+class ArrayDemoSpec extends FlatSpec with Matchers {
+
+  behavior of "ArrayDemoTest"
+
+  it should "find value after insert" in {
+    val demo = new ArrayDemo(10)
+    assert(demo.insert(0, 'a'))
+    assert(demo.insert(1, 'b'))
+    assert(demo.insert(2, 'c'))
+    assert(demo.insert(3, 'd'))
+    assert(demo.insert(4, 'e'))
+    demo.print should equal("abcde")
+
+    assert(demo.insert(2, 'x'))
+    demo.print should equal("abxcde")
+  }
+
+  it should "not insert value if capacity is full " in {
+    val demo = new ArrayDemo(10)
+    for (i <- Range(0, 10)) {
+      demo.insert(i, (i + 97).toChar)
+    }
+
+    assert(!demo.insert(1, 'a'))
+  }
+
+  it should "not insert if index is negative" in {
+    val demo = new ArrayDemo(10)
+    assert(!demo.insert(-1, 'a'))
+  }
+
+  it should "not insert if index is exceed capacity" in {
+    val demo = new ArrayDemo(10)
+    assert(!demo.insert(10, 'a'))
+    assert(!demo.insert(11, 'a'))
+  }
+
+  it should "not find after delete" in {
+    val demo = new ArrayDemo(10)
+    assert(demo.insert(0, 'a'))
+    assert(demo.insert(1, 'b'))
+    assert(demo.insert(2, 'c'))
+    assert(demo.insert(3, 'd'))
+    assert(demo.insert(4, 'e'))
+    demo.print should equal("abcde")
+
+
+    assert(demo.insert(2, 'x'))
+    demo.print should equal("abxcde")
+
+    demo.delete(2) should equal('x')
+    demo.find(2) should not equal ('x')
+    demo.print should equal("abcde")
+  }
+
+  it should "not delete for empty array" in {
+    val demo = new ArrayDemo(10)
+    assertThrows[IllegalStateException] {
+      demo.delete(2) should equal('x')
+    }
+  }
+
+}