1 files changed, 75 insertions, 0 deletions
diff --git a/catapult/devil/devil/utils/decorators_test.py b/catapult/devil/devil/utils/decorators_test.py
new file mode 100755
index 00000000..f81974ac
--- /dev/null
+++ b/catapult/devil/devil/utils/decorators_test.py
@@ -0,0 +1,75 @@
+#!/usr/bin/env python
+# Copyright 2021 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Unit tests for decorators.py."""
+
+import unittest
+
+from devil.utils import decorators
+
+
+class MemoizeDecoratorTest(unittest.TestCase):
+
+  def testFunctionExceptionNotMemoized(self):
+    """Tests that |Memoize| decorator does not cache exception results."""
+
+    class ExceptionType1(Exception):
+      pass
+
+    class ExceptionType2(Exception):
+      pass
+
+    @decorators.Memoize
+    def raiseExceptions():
+      if raiseExceptions.count == 0:
+        raiseExceptions.count += 1
+        raise ExceptionType1()
+
+      if raiseExceptions.count == 1:
+        raise ExceptionType2()
+    raiseExceptions.count = 0
+
+    with self.assertRaises(ExceptionType1):
+      raiseExceptions()
+    with self.assertRaises(ExceptionType2):
+      raiseExceptions()
+
+  def testFunctionResultMemoized(self):
+    """Tests that |Memoize| decorator caches results."""
+
+    @decorators.Memoize
+    def memoized():
+      memoized.count += 1
+      return memoized.count
+    memoized.count = 0
+
+    def notMemoized():
+      notMemoized.count += 1
+      return notMemoized.count
+    notMemoized.count = 0
+
+    self.assertEquals(memoized(), 1)
+    self.assertEquals(memoized(), 1)
+    self.assertEquals(memoized(), 1)
+
+    self.assertEquals(notMemoized(), 1)
+    self.assertEquals(notMemoized(), 2)
+    self.assertEquals(notMemoized(), 3)
+
+  def testFunctionMemoizedBasedOnArgs(self):
+    """Tests that |Memoize| caches results based on args and kwargs."""
+
+    @decorators.Memoize
+    def returnValueBasedOnArgsKwargs(a, k=0):
+      return a + k
+
+    self.assertEquals(returnValueBasedOnArgsKwargs(1, 1), 2)
+    self.assertEquals(returnValueBasedOnArgsKwargs(1, 2), 3)
+    self.assertEquals(returnValueBasedOnArgsKwargs(2, 1), 3)
+    self.assertEquals(returnValueBasedOnArgsKwargs(3, 3), 6)
+
+
+if __name__ == '__main__':
+  unittest.main()