Travis CI: Add more flake8 tests (keon#512)

* Travis CI: Add more flake8 tests

* Use ==/!= to compare str, bytes, and int literals

Identity is not the same thing as equality in Python.

* Use ==/!= to compare str, bytes, and int literals

Author: cclauss

.travis.yml

@@ -16,7 +16,7 @@ install:
     - pip install -r test_requirements.txt
 before_script:
     # stop the build if there are Python syntax errors or undefined names
-    - flake8 . --count --select=E901,E999,F821,F822,F823 --show-source --statistics
+    - flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
     # exit-zero treats all errors as warnings.  The GitHub editor is 127 chars wide
     - flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
 script:

algorithms/arrays/move_zeros.py

@@ -13,7 +13,7 @@ def move_zeros(array):
     zeros = 0
 
     for i in array:
-        if i is 0:  # not using `not i` to avoid `False`, `[]`, etc.
+        if i == 0:  # not using `not i` to avoid `False`, `[]`, etc.
             zeros += 1
         else:
             result.append(i)

algorithms/tree/red_black_tree/red_black_tree.py

@@ -93,10 +93,10 @@ def fix_insert(self, node):
             return
             # case 2 the parent color is black, do nothing
         # case 3 the parent color is red
-        while node.parent and node.parent.color is 1:
+        while node.parent and node.parent.color == 1:
             if node.parent is node.parent.parent.left:
                 uncle_node = node.parent.parent.right
-                if uncle_node and uncle_node.color is 1:
+                if uncle_node and uncle_node.color == 1:
                     # case 3.1 the uncle node is red
                     # then set parent and uncle color is black and grandparent is red
                     # then node => node.parent
@@ -118,7 +118,7 @@ def fix_insert(self, node):
                 self.right_rotate(node.parent.parent)
             else:
                 uncle_node = node.parent.parent.left
-                if uncle_node and uncle_node.color is 1:
+                if uncle_node and uncle_node.color == 1:
                     # case 3.1 the uncle node is red
                     # then set parent and uncle color is black and grandparent is red
                     # then node => node.parent