[Predator] Move ``FilterStackBuffer`` from stack parser to ``AddFilteredStack`` of stacktrace buffe…

appengine/findit/crash/test/stacktrace_test.py

 # Copyright 2016 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.
 
 from common.dependency import Dependency
 from crash.stacktrace import CallStack
 from crash.stacktrace import CallStackBuffer
 from crash.stacktrace import StackFrame
 from crash.stacktrace import Stacktrace
 from crash.stacktrace import StacktraceBuffer
@@ skipping 184 matching lines @@
 
     stack1 = CallStack(0, frame_list1, None, None)
     stack2 = CallStack(1, frame_list2, None, None)
     stacktrace = Stacktrace((stack1, stack2), stack1)
     for stack in stacktrace:
       self.assertEqual(len(stack), 1)
 
 
 class StacktraceBufferTest(StacktraceTestSuite):
 
+  def _DummyFilter(self, stack_buffer):  # pragma: no cover
+    return stack_buffer
+
   def testStacktraceBufferWithoutSignature(self):
     """Tests using least priority stack as crash_stack without  signature."""
     frame_list1 = [
         StackFrame(0, 'src/', 'func', 'file0.cc', 'src/file0.cc', [32])]
-
     frame_list2 = [
         StackFrame(0, 'src/', 'func2', 'file0.cc', 'src/file0.cc', [32])]
 
     stack1 = CallStackBuffer(0, frame_list=frame_list1)
     stack2 = CallStackBuffer(1, frame_list=frame_list2)
     stacktrace = StacktraceBuffer([stack1, stack2]).ToStacktrace()
 
     self._VerifyTwoCallStacksEqual(stacktrace.crash_stack, stack1.ToCallStack())
 
   def testStacktraceBufferWithSignature(self):
     """Tests using stack with signature as crash_stack with signature."""
     frame_list1 = [
         StackFrame(0, 'src/', 'func', 'file0.cc', 'src/file0.cc', [32])]
 
     frame_list2 = [
         StackFrame(0, 'src/', 'signature_func2', 'f.cc', 'src/f.cc', [32])]
 
     stack1 = CallStackBuffer(0, frame_list=frame_list1)
     stack2 = CallStackBuffer(1, frame_list=frame_list2)
     stacktrace = StacktraceBuffer([stack1, stack2], 'signature').ToStacktrace()
 
     self._VerifyTwoCallStacksEqual(stacktrace.crash_stack, stack2.ToCallStack())
 
+  def testAddFitleredStackWithNoFilters(self):
+    """Tests that ``AddFilteredStack`` returns None if there is no filters."""
+    frame_list = [
+        StackFrame(0, 'src/', 'func', 'file0.cc', 'src/file0.cc', [32]),
+        StackFrame(0, 'src/', 'func2', 'file0.cc', 'src/file0.cc', [32])]
+    stack_buffer = CallStackBuffer(0, frame_list=frame_list)
+    stacktrace_buffer = StacktraceBuffer()
+    stacktrace_buffer.AddFilteredStack(stack_buffer)
+    self.assertEqual(len(stacktrace_buffer.stacks), 1)
+
+  def testFilterInfinityPriorityStackBuffer(self):
+    """Tests that ``AddFilteredStack`` returns None for inf priority stack."""
+    stack_buffer = CallStackBuffer(priority=float('inf'))
+    stacktrace_buffer = StacktraceBuffer(filters=[self._DummyFilter])
+    stacktrace_buffer.AddFilteredStack(stack_buffer)
+    self.assertEqual(len(stacktrace_buffer.stacks), 0)
+
+  def testFilterEmptyStackBuffer(self):
+    """Tests that ``AddFilteredStack`` returns None for empty stack buffer."""
+    stack_buffer = CallStackBuffer(frame_list=[])
+    stacktrace_buffer = StacktraceBuffer(filters=[self._DummyFilter])
+    stacktrace_buffer.AddFilteredStack(stack_buffer)
+    self.assertEqual(len(stacktrace_buffer.stacks), 0)
+
+  def testFilterAllFrames(self):
+    """Tests that ``AddFilteredStack`` filters all frames and resturns None."""
+    frame_list = [
+        StackFrame(0, 'src/', 'func', 'file0.cc', 'src/file0.cc', [32]),
+        StackFrame(0, 'src/', 'func2', 'file0.cc', 'src/file0.cc', [32])]
+    stack_buffer = CallStackBuffer(0, frame_list=frame_list)
+
+    def _MockFilterAllFrames(stack_buffer):
+      stack_buffer.frames = None
+      return stack_buffer
+
+    stacktrace_buffer = StacktraceBuffer(filters=[_MockFilterAllFrames])
+    stacktrace_buffer.AddFilteredStack(stack_buffer)
+    self.assertEqual(len(stacktrace_buffer.stacks), 0)
+
+  def testFilterSomeFrames(self):
+    """Tests that ``AddFilteredStack`` filters some frames."""
+    frame_list = [
+        StackFrame(0, 'src/', 'func', 'file0.cc', 'src/file0.cc', [32]),
+        StackFrame(0, 'src/', 'func2', 'file0.cc', 'src/file0.cc', [32])]
+    stack_buffer = CallStackBuffer(0, frame_list=frame_list)
+
+    def _MockKeepFirstFrame(stack):
+      stack.frames = stack.frames[:1]
+      return stack
+
+    stacktrace_buffer = StacktraceBuffer(filters=[_MockKeepFirstFrame])
+    stacktrace_buffer.AddFilteredStack(stack_buffer)
+    self._VerifyTwoCallStacksEqual(
+        stacktrace_buffer.stacks[0],
+        CallStackBuffer(stack_buffer.priority, frame_list=frame_list[:1]))
+
   def testEmptyStacktraceBufferToStacktrace(self):
-    """Tests ``ToStacktrace`` returns None for empty stacktrace buffer."""
+    """Tests that ``ToStacktrace`` returns None for empty stacktrace buffer."""
     self.assertIsNone(StacktraceBuffer([]).ToStacktrace())