added index_of_with_escape function

tests/test_private.py

@@ -1,6 +1,6 @@
 import unittest
 
-from pwo import retry, async_retry, async_test, AsyncQueueIterator, aenumerate
+from pwo import retry, async_retry, async_test, AsyncQueueIterator, aenumerate, index_of_with_escape
 from asyncio import Queue
 
 
@@ -93,3 +93,35 @@ class PrivateTest(unittest.TestCase):
         self.assertEqual(queue_size, processed)
 
 
+class TestIndexOfWithEscape(unittest.TestCase):
+
+    def run_test_case(self, haystack, needle, escape, expected_solution):
+        solution = []
+        i = 0
+        while True:
+            i = index_of_with_escape(haystack, needle, escape, i, len(haystack))
+            if i < 0:
+                break
+            solution.append(i)
+            i += 1
+        self.assertEqual(solution, expected_solution)
+
+    def test_simple(self):
+        self.run_test_case(" dsds $sdsa \\$dfivbdsf \\\\$sdgsga", '$', '\\', [6, 25])
+
+    def test_simple2(self):
+        self.run_test_case("asdasd$$vdfv$", '$', '$', [12])
+
+    def test_no_needle(self):
+        self.run_test_case("asdasd$$vdfv$", '#', '\\', [])
+
+    def test_escaped_needle(self):
+        self.run_test_case("asdasd$$vdfv$#sdfs", '#', '$', [])
+
+    def test_not_escaped_needle(self):
+        self.run_test_case("asdasd$$#vdfv$#sdfs", '#', '$', [8])
+
+    def test_special_case(self):
+        self.run_test_case("\n${sys:user.home}${env:HOME}", ':', '\\', [6, 22])
+
+