Merge branch 'add-random-number-function' of https://github.com/kaaqu…

…ist/feel-scala into kaaquist-add-random-number-function
camunda · Oct 6, 2022 · ad33eab · ad33eab
2 parents 4258847 + e96dcd1
commit ad33eab
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diff --git a/docs/docs/reference/builtin-functions/feel-built-in-functions-numeric.md b/docs/docs/reference/builtin-functions/feel-built-in-functions-numeric.md
@@ -254,3 +254,16 @@ even(5)
 even(2)
 // true
 ```
+
+## random number()
+
+Returns number between 0 and 1
+
+- parameters: 
+  - NaN
+- result: number
+
+```js
+random number()
+// 0.9701618132579795
+```
diff --git a/src/main/scala/org/camunda/feel/impl/builtin/NumericBuiltinFunctions.scala b/src/main/scala/org/camunda/feel/impl/builtin/NumericBuiltinFunctions.scala
@@ -14,6 +14,7 @@ import org.camunda.feel.syntaxtree.{
 }
 
 import scala.math.BigDecimal.RoundingMode
+import scala.util.Random
 
 object NumericBuiltinFunctions {
 
@@ -32,7 +33,8 @@ object NumericBuiltinFunctions {
     "round up" -> List(roundUpFunction),
     "round down" -> List(roundDownFunction),
     "round half up" -> List(roundHalfUpFunction),
-    "round half down" -> List(roundHalfDownFunction)
+    "round half down" -> List(roundHalfDownFunction),
+    "random number" -> List(randomNumberFunction)
   )
 
   private def decimalFunction = builtinFunction(
@@ -164,4 +166,10 @@ object NumericBuiltinFunctions {
       case List(ValNumber(n), ValNumber(scale)) =>
         round(n, scale, RoundingMode.HALF_DOWN)
     })
+
+  private def randomNumberFunction =
+    builtinFunction(params = List(), invoke = {
+      case List() =>
+        ValNumber(Random.nextDouble())
+    })
 }
diff --git a/src/test/scala/org/camunda/feel/impl/builtin/BuiltinNumberFunctionTest.scala b/src/test/scala/org/camunda/feel/impl/builtin/BuiltinNumberFunctionTest.scala
@@ -17,6 +17,7 @@
 package org.camunda.feel.impl.builtin
 
 import org.camunda.feel.impl.FeelIntegrationTest
+import org.camunda.feel.syntaxtree
 import org.camunda.feel.syntaxtree._
 import org.scalatest.matchers.should.Matchers
 import org.scalatest.flatspec.AnyFlatSpec
@@ -259,4 +260,17 @@ class BuiltinNumberFunctionsTest
     eval(" round half down(-1.126, 2) ") should be(ValNumber(-1.13))
   }
 
+
+  "A random number() function" should "return a number" in {
+
+    eval(" random number() ") shouldBe a [ValNumber]
+  }
+
+  it should "return a number between 0.0 and 1.0 " in {
+
+    eval(" random number() ") match {
+      case ValNumber(x) => x should (be >= BigDecimal(0) and be <= BigDecimal(1))
+      case other => fail()
+    }
+  }
 }