diff --git a/python/11_sorts/sorts.py b/python/11_sorts/sorts.py
index 127a647..aed133e 100644
--- a/python/11_sorts/sorts.py
+++ b/python/11_sorts/sorts.py
@@ -7,94 +7,99 @@
 
 from typing import List
 
+
 # 冒泡排序
 def bubble_sort(a: List[int]):
-    if len(a) <= 1: return
-    
-<<<<<<< HEAD
-    made_swap = False
-    for i in range(len(a)):
-=======
-    for i in range(len(a)):
+    length = len(a)
+    if length <= 1:
+        return
+
+    for i in range(length):
         made_swap = False
->>>>>>> upstream/master
-        for j in range(len(a) - i - 1):
-            if a[j] > a[j+1]:
-                a[j], a[j+1] = a[j+1], a[j]
+        for j in range(length - i - 1):
+            if a[j] > a[j + 1]:
+                a[j], a[j + 1] = a[j + 1], a[j]
                 made_swap = True
-        if not made_swap: break
+        if not made_swap:
+            break
+
 
 # 插入排序
 def insertion_sort(a: List[int]):
-    if len(a) <= 1: return
-    
-    for i in range(1, len(a)):
+    length = len(a)
+    if length <= 1:
+        return
+
+    for i in range(1, length):
         value = a[i]
         j = i - 1
         while j >= 0 and a[j] > value:
-            a[j+1] = a[j]
+            a[j + 1] = a[j]
             j -= 1
-        a[j+1] = value
+        a[j + 1] = value
+
 
 # 选择排序
 def selection_sort(a: List[int]):
-    if len(a) <= 1: return
-    
-    for i in range(len(a)):
+    length = len(a)
+    if length <= 1:
+        return
+
+    for i in range(length):
         min_index = i
         min_val = a[i]
-        for j in range(i, len(a)):
+        for j in range(i, length):
             if a[j] < min_val:
                 min_val = a[j]
                 min_index = j
         a[i], a[min_index] = a[min_index], a[i]
 
 
+def test_bubble_sort():
+    test_array = [1, 1, 1, 1]
+    bubble_sort(test_array)
+    assert test_array == [1, 1, 1, 1]
+    test_array = [4, 1, 2, 3]
+    bubble_sort(test_array)
+    assert test_array == [1, 2, 3, 4]
+    test_array = [4, 3, 2, 1]
+    bubble_sort(test_array)
+    assert test_array == [1, 2, 3, 4]
+
+
+def test_insertion_sort():
+    test_array = [1, 1, 1, 1]
+    insertion_sort(test_array)
+    assert test_array == [1, 1, 1, 1]
+    test_array = [4, 1, 2, 3]
+    insertion_sort(test_array)
+    assert test_array == [1, 2, 3, 4]
+    test_array = [4, 3, 2, 1]
+    insertion_sort(test_array)
+    assert test_array == [1, 2, 3, 4]
+
+
+def test_selection_sort():
+    test_array = [1, 1, 1, 1]
+    selection_sort(test_array)
+    assert test_array == [1, 1, 1, 1]
+    test_array = [4, 1, 2, 3]
+    selection_sort(test_array)
+    assert test_array == [1, 2, 3, 4]
+    test_array = [4, 3, 2, 1]
+    selection_sort(test_array)
+    assert test_array == [1, 2, 3, 4]
+
+
 if __name__ == "__main__":
-    array = [1, 1, 1, 1]
-    bubble_sort(array)
-    print(array)
-
-    array = [1, 2, 3, 4]
-    bubble_sort(array)
-    print(array)
-
-    array = [4, 3, 2, 1]
-    bubble_sort(array)
-    print(array)
-
     array = [5, 6, -1, 4, 2, 8, 10, 7, 6]
     bubble_sort(array)
     print(array)
 
-    array = [1, 1, 1, 1]
-    insertion_sort(array)
-    print(array)
-
-    array = [1, 2, 3, 4]
-    insertion_sort(array)
-    print(array)
-
-    array = [4, 3, 2, 1]
-    insertion_sort(array)
-    print(array)
-
     array = [5, 6, -1, 4, 2, 8, 10, 7, 6]
     insertion_sort(array)
     print(array)
 
-    array = [1, 1, 1, 1]
-    selection_sort(array)
-    print(array)
-
-    array = [1, 2, 3, 4]
-    selection_sort(array)
-    print(array)
-
-    array = [4, 3, 2, 1]
-    selection_sort(array)
-    print(array)
-
     array = [5, 6, -1, 4, 2, 8, 10, 7, 6]
     selection_sort(array)
-    print(array)
\ No newline at end of file
+    print(array)