Kinetic test at unity3d - apply initial forces and stop rigidbody2d at random time

KineticTest.cs

using UnityEngine;
using System.Collections;
using UnityTest;

/// <summary>
/// 
/// Kinetic test.
/// 
/// some usefull info here http://www.moaisnippets.info/using-box2d-impulses-to-move-objects
/// impulse = mass * velocity;
/// 
/// you have to use ForceMode2D.Impulse  to apply impulse to the body.
/// ForceMode2D.Force - assume you apply impulse at FixedDeltaTime amount of time
/// </summary>

public class KineticTest : MonoBehaviour {
	public Vector2 StartForce = new Vector2(1000,0);
	public float TestTimeoutMin = 0.5f;
	public float TestTimeoutMax = 0.7f;
	// Use this for initialization
	public float FloatEpsilon = 0.01f;
	
	IAssertionComponentConfigurator startSpeed;
	IAssertionComponentConfigurator endSpeed;
	void Awake(){
		FloatComparer startAbsSpeed = AssertionComponent.Create<FloatComparer>(out startSpeed, (UnityTest.CheckMethod)0, gameObject, "Rigidbody2D.velocity.x", 0.0f);
		startAbsSpeed.floatingPointError = FloatEpsilon;
		startAbsSpeed.compareTypes = FloatComparer.CompareTypes.Greater;


		FloatComparer endAbsSpeed = AssertionComponent.Create<FloatComparer>(out endSpeed, (UnityTest.CheckMethod)0, gameObject, "Rigidbody2D.velocity.x", 0.0f);
		endAbsSpeed.floatingPointError = FloatEpsilon;
		endAbsSpeed.compareTypes = FloatComparer.CompareTypes.Equal;
	}

	void Start(){
		StartCoroutine(DoStart());
	}

	IEnumerator DoStart () {
		float velocityX;
		yield return new WaitForSeconds(0.1f);
		rigidbody2D.AddForce(StartForce);
		yield return new WaitForSeconds(Random.Range(TestTimeoutMin, TestTimeoutMax));
		velocityX = rigidbody2D.velocity.x;
		float impulseX = velocityX  * rigidbody2D.mass;
		Assertions.CheckAssertions(startSpeed as AssertionComponent);
		rigidbody2D.AddForce(new Vector2( -impulseX, 0.0f), ForceMode2D.Impulse); //try Force it won't work 

		yield return null;	
		Assertions.CheckAssertions(endSpeed as AssertionComponent);
	}

}