EditorWindowからコルーチンを実行させるコードサンプル

TestCoroutineWindow.cs

namespace hoge
{
    using UnityEngine;
    using UnityEditor;
    using System.Collections;
    using System.Reflection;

    public class TestCoroutineWindow : EditorWindow
    {
        public TestMonobehaviour targetObject;
        
        [MenuItem("EditorWindow/EditorWindowからコルーチンを実行させるサンプル")]
        static void Open()
        {
            GetWindow<TestCoroutineWindow>();
        }

        void OnGUI()
        {
            this.targetObject = (TestMonobehaviour) EditorGUILayout.ObjectField(this.targetObject, typeof(TestMonobehaviour), true);

            if (GUILayout.Button("コルーチン実行"))
            {
                this.ExecCoroutine();
            }
        }

        void ExecCoroutine()
        {
            // メソッドを取り出す
            var component = targetObject.GetComponent<TestMonobehaviour>();
            var flag = BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance;
            var method = typeof(TestMonobehaviour).GetMethod("TestCoroutine", flag);

            // StartCoroutineを取り出す
            var argumentTypes = new System.Type[] { typeof(IEnumerator) };
            var startCoroutine = typeof(TestMonobehaviour).GetMethod("StartCoroutine", argumentTypes);

            // メソッドを実行してIEnumeratorを取得
            object[] parameters = new object[0]{};
            var coroutine = method.Invoke(component, parameters);

            // コルーチン実行
            startCoroutine.Invoke(component, new object[] { coroutine });
        }
        
    }
}

TestMonobehaviour.cs

namespace hoge
{
    using UnityEngine;
    using System.Collections;

    public class TestMonobehaviour : MonoBehaviour
    {
        private IEnumerator TestCoroutine()
        {
            Debug.Log("TestCoroutine Start");   
            yield return new WaitForSeconds(1f);
            Debug.Log("TestCoroutine Done");
        }
    }
}