diff --git a/tools/releasetools/test_verity_utils.py b/tools/releasetools/test_verity_utils.py
index 1cc539f..d02bc7f 100644
--- a/tools/releasetools/test_verity_utils.py
+++ b/tools/releasetools/test_verity_utils.py
@@ -47,25 +47,22 @@
     }
 
     self.hash_algorithm = "sha256"
-    self.fixed_salt = \
-        "aee087a5be3b982978c923f566a94613496b417f2af592639bc80d141e34dfe7"
-    self.expected_root_hash = \
-        "0b7c4565e87b1026e11fbab91c0bc29e185c847a5b44d40e6e86e461e8adf80d"
+    self.fixed_salt = (
+        "aee087a5be3b982978c923f566a94613496b417f2af592639bc80d141e34dfe7")
+    self.expected_root_hash = (
+        "0b7c4565e87b1026e11fbab91c0bc29e185c847a5b44d40e6e86e461e8adf80d")
 
-  def _create_simg(self, raw_data):
+  def _CreateSimg(self, raw_data):  # pylint: disable=no-self-use
     output_file = common.MakeTempFile()
     raw_image = common.MakeTempFile()
     with open(raw_image, 'wb') as f:
       f.write(raw_data)
 
     cmd = ["img2simg", raw_image, output_file, '4096']
-    p = common.Run(cmd)
-    p.communicate()
-    self.assertEqual(0, p.returncode)
-
+    common.RunAndCheckOutput(cmd)
     return output_file
 
-  def _generate_image(self):
+  def _GenerateImage(self):
     partition_size = 1024 * 1024
     prop_dict = {
         'partition_size': str(partition_size),
@@ -79,11 +76,11 @@
     self.assertIsNotNone(verity_image_builder)
     adjusted_size = verity_image_builder.CalculateMaxImageSize()
 
-    raw_image = ""
+    raw_image = bytearray(adjusted_size)
     for i in range(adjusted_size):
-      raw_image += str(i % 10)
+      raw_image[i] = ord('0') + i % 10
 
-    output_file = self._create_simg(raw_image)
+    output_file = self._CreateSimg(raw_image)
 
     # Append the verity metadata.
     verity_image_builder.Build(output_file)
@@ -92,7 +89,7 @@
 
   @SkipIfExternalToolsUnavailable()
   def test_CreateHashtreeInfoGenerator(self):
-    image_file = sparse_img.SparseImage(self._generate_image())
+    image_file = sparse_img.SparseImage(self._GenerateImage())
 
     generator = CreateHashtreeInfoGenerator(
         'system', image_file, self.prop_dict)
@@ -103,7 +100,7 @@
 
   @SkipIfExternalToolsUnavailable()
   def test_DecomposeSparseImage(self):
-    image_file = sparse_img.SparseImage(self._generate_image())
+    image_file = sparse_img.SparseImage(self._GenerateImage())
 
     generator = VerifiedBootVersion1HashtreeInfoGenerator(
         self.partition_size, 4096, True)
@@ -114,7 +111,7 @@
 
   @SkipIfExternalToolsUnavailable()
   def test_ParseHashtreeMetadata(self):
-    image_file = sparse_img.SparseImage(self._generate_image())
+    image_file = sparse_img.SparseImage(self._GenerateImage())
     generator = VerifiedBootVersion1HashtreeInfoGenerator(
         self.partition_size, 4096, True)
     generator.DecomposeSparseImage(image_file)
@@ -131,12 +128,12 @@
   def test_ValidateHashtree_smoke(self):
     generator = VerifiedBootVersion1HashtreeInfoGenerator(
         self.partition_size, 4096, True)
-    generator.image = sparse_img.SparseImage(self._generate_image())
+    generator.image = sparse_img.SparseImage(self._GenerateImage())
 
     generator.hashtree_info = info = HashtreeInfo()
-    info.filesystem_range = RangeSet(data=[0, 991232 / 4096])
+    info.filesystem_range = RangeSet(data=[0, 991232 // 4096])
     info.hashtree_range = RangeSet(
-        data=[991232 / 4096, (991232 + 12288) / 4096])
+        data=[991232 // 4096, (991232 + 12288) // 4096])
     info.hash_algorithm = self.hash_algorithm
     info.salt = self.fixed_salt
     info.root_hash = self.expected_root_hash
@@ -147,12 +144,12 @@
   def test_ValidateHashtree_failure(self):
     generator = VerifiedBootVersion1HashtreeInfoGenerator(
         self.partition_size, 4096, True)
-    generator.image = sparse_img.SparseImage(self._generate_image())
+    generator.image = sparse_img.SparseImage(self._GenerateImage())
 
     generator.hashtree_info = info = HashtreeInfo()
-    info.filesystem_range = RangeSet(data=[0, 991232 / 4096])
+    info.filesystem_range = RangeSet(data=[0, 991232 // 4096])
     info.hashtree_range = RangeSet(
-        data=[991232 / 4096, (991232 + 12288) / 4096])
+        data=[991232 // 4096, (991232 + 12288) // 4096])
     info.hash_algorithm = self.hash_algorithm
     info.salt = self.fixed_salt
     info.root_hash = "a" + self.expected_root_hash[1:]
@@ -161,12 +158,12 @@
 
   @SkipIfExternalToolsUnavailable()
   def test_Generate(self):
-    image_file = sparse_img.SparseImage(self._generate_image())
+    image_file = sparse_img.SparseImage(self._GenerateImage())
     generator = CreateHashtreeInfoGenerator('system', 4096, self.prop_dict)
     info = generator.Generate(image_file)
 
-    self.assertEqual(RangeSet(data=[0, 991232 / 4096]), info.filesystem_range)
-    self.assertEqual(RangeSet(data=[991232 / 4096, (991232 + 12288) / 4096]),
+    self.assertEqual(RangeSet(data=[0, 991232 // 4096]), info.filesystem_range)
+    self.assertEqual(RangeSet(data=[991232 // 4096, (991232 + 12288) // 4096]),
                      info.hashtree_range)
     self.assertEqual(self.hash_algorithm, info.hash_algorithm)
     self.assertEqual(self.fixed_salt, info.salt)