Merge pull request #1524 from yadavan88/remove-element

Code for removing element from a list

Author: dominiqueplante

scala-core-collections-modules/scala-core-collections-4/src/test/scala/com/baeldung/scala/removeelement/RemoveMatchingElementUnitTest.scala

@@ -0,0 +1,118 @@
+package com.baeldung.scala.removeelement
+
+import org.scalatest.flatspec.AnyFlatSpec
+import org.scalatest.matchers.should.Matchers
+import org.scalatest.prop.TableDrivenPropertyChecks
+
+import scala.collection.mutable.{ArrayBuffer, ListBuffer}
+
+class RemoveMatchingElementUnitTest
+  extends AnyFlatSpec
+  with Matchers
+  with TableDrivenPropertyChecks {
+
+  //format: off
+  val firstMatchTable = Table(
+    ("input", "elementToRemove", "expected"),
+    (List("abc", "def", "xyz", "abc"), "abc" ,List("def", "xyz", "abc")),
+    (List("abc", "def", "xyz", "abc"), "abcd" ,List("abc", "def", "xyz", "abc")),
+    (List.empty[String], "abcd" ,List.empty[String]),
+  )
+
+  val allMatchTable = Table(
+    ("input", "elementToRemove", "expected"),
+    (List("abc", "def", "xyz", "abc"), "abc", List("def", "xyz")),
+    (List("abc", "def", "xyz", "abc"), "abcd", List("abc", "def", "xyz", "abc")),
+    (List.empty[String], "abcd", List.empty[String]),
+  )
+  //format on
+
+  // on immutable collections
+  it should "remove first match using span" in {
+    forAll(firstMatchTable) { (input, ele, exp) =>
+      val (part1, part2)= input.span(_ != ele)
+      val result = part1 ++ part2.drop(1)
+      result shouldBe exp
+    }
+  }
+
+  it should "remove first match using pattern matching" in {
+    forAll(firstMatchTable) { (input, ele, exp) =>
+      val result = input match {
+        case `ele` :: sub => sub
+        case sub => sub
+      }
+      result shouldBe exp
+    }
+  }
+
+  it should "remove all matches using partition" in {
+    forAll(allMatchTable) { (input, ele, exp) =>
+      val (part1, _) = input.partition(_ != ele)
+      val result = part1
+      result shouldBe exp
+    }
+  }
+
+  // on mutable collections
+  it should "remove first match from mutable list" in {
+    val buffer = ListBuffer[String]("abc", "def", "xyz", "def")
+    buffer -= "def"
+    buffer shouldBe ListBuffer[String]("abc", "xyz", "def")
+  }
+
+  it should "remove all matches from mutable list using filterInPlace" in {
+    val buffer = ListBuffer[String]("abc", "def", "xyz", "def")
+    buffer.filterInPlace(_ != "def")
+    buffer shouldBe ListBuffer[String]("abc", "xyz")
+  }
+
+  it should "remove all matches from mutable list using filter" in {
+    val list = List("abc", "def", "xyz", "def")
+    val filteredList = list.filter(_ != "def")
+    filteredList shouldBe List("abc", "xyz")
+    list.filterNot(_ == "def") shouldBe List("abc", "xyz")
+    // on ListBuffer
+    val buffer = ListBuffer[String]("abc", "def", "xyz", "def")
+    val newBuffer = buffer.filter(_ != "def")
+    newBuffer shouldBe ListBuffer[String]("abc", "xyz")
+  }
+
+  // remove multiple matches
+  it should "remove all matches using collect" in {
+    forAll(allMatchTable) { (input, ele, exp) =>
+      val result = input.collect {
+        case e if e != ele => e
+      }
+      result shouldBe exp
+    }
+  }
+
+  it should "remove all matches using filter" in {
+    forAll(allMatchTable) { (input, ele, exp) =>
+      val result = input.filter(_ != ele)
+      result shouldBe exp
+      val result2 = input.filterNot(_ == ele)
+      result2 shouldBe exp
+    }
+  }
+
+  it should "remove all matches using recursion" in {
+    forAll(allMatchTable) { (input, ele, exp) =>
+      val result = input.foldLeft(List.empty[String])((acc,i) => if(i != ele) acc :+ i else acc)
+      result shouldBe exp
+    }
+  }
+
+  it should "remove all matches from mutable ListBuffer" in {
+    val buffer = ListBuffer[String]("abc", "def", "xyz", "def")
+    buffer.filterInPlace(_ != "def")
+    buffer shouldBe ListBuffer[String]("abc", "xyz")
+  }
+
+  it should "remove all matches from mutable ArrayBuffer" in {
+    val buffer = ArrayBuffer[String]("abc", "def", "xyz", "def")
+    buffer.filterInPlace(_ != "def")
+    buffer shouldBe ListBuffer[String]("abc", "xyz")
+  }
+}