diff --git a/Dynamic-Programming/TrappingRainWater.js b/Dynamic-Programming/TrappingRainWater.js
index 2b3951fdb..bea568cbc 100644
--- a/Dynamic-Programming/TrappingRainWater.js
+++ b/Dynamic-Programming/TrappingRainWater.js
@@ -35,7 +35,7 @@ right maxes =     [3,3,3,3,3,3,3,2,2,2,1,0]
 water contained = [0,0,1,0,1,2,1,0,0,1,0,0] -> sum = 6
 */
 
-function trap (heights) {
+export const trap = (heights) => {
   const maxes = new Array(heights.length).fill(0)
 
   let leftMax = 0
@@ -59,5 +59,3 @@ function trap (heights) {
   }
   return maxes.reduce((a, b) => a + b, 0)
 }
-
-console.log(trap([0, 1, 0, 2, 1, 0, 1, 3, 2, 1, 2, 1])) // -> 6
diff --git a/Dynamic-Programming/tests/TrappingRainWater.test.js b/Dynamic-Programming/tests/TrappingRainWater.test.js
new file mode 100644
index 000000000..54437bd78
--- /dev/null
+++ b/Dynamic-Programming/tests/TrappingRainWater.test.js
@@ -0,0 +1,11 @@
+import { trap } from '../TrappingRainWater'
+
+describe('TrappingRainWater', () => {
+  it('expects 6 units of rain water are being trapped', () => {
+    expect(trap([0,1,0,2,1,0,1,3,2,1,2,1])).toBe(6)
+  })
+
+  it('expects 9 units of rain water are being trapped', () => {
+    expect(trap([4,2,0,3,2,5])).toBe(9)
+  })
+})