Initial import.

1 files changed, 758 insertions, 0 deletions

diff --git a/chromium/tools/code_coverage/croc_test.py b/chromium/tools/code_coverage/croc_test.py
new file mode 100755
index 00000000000..7c2521ca3df
--- /dev/null
+++ b/chromium/tools/code_coverage/croc_test.py
@@ -0,0 +1,758 @@
+#!/usr/bin/env python
+# Copyright (c) 2011 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 Crocodile."""
+
+import os
+import StringIO
+import unittest
+import croc
+
+
+class TestCoverageStats(unittest.TestCase):
+  """Tests for croc.CoverageStats."""
+
+  def testAdd(self):
+    """Test Add()."""
+    c = croc.CoverageStats()
+
+    # Initially empty
+    self.assertEqual(c, {})
+
+    # Add items
+    c['a'] = 1
+    c['b'] = 0
+    self.assertEqual(c, {'a': 1, 'b': 0})
+
+    # Add dict with non-overlapping items
+    c.Add({'c': 5})
+    self.assertEqual(c, {'a': 1, 'b': 0, 'c': 5})
+
+    # Add dict with overlapping items
+    c.Add({'a': 4, 'd': 3})
+    self.assertEqual(c, {'a': 5, 'b': 0, 'c': 5, 'd': 3})
+
+
+class TestCoveredFile(unittest.TestCase):
+  """Tests for croc.CoveredFile."""
+
+  def setUp(self):
+    self.cov_file = croc.CoveredFile('bob.cc', group='source', language='C++')
+
+  def testInit(self):
+    """Test init."""
+    f = self.cov_file
+
+    # Check initial values
+    self.assertEqual(f.filename, 'bob.cc')
+    self.assertEqual(f.attrs, {'group': 'source', 'language': 'C++'})
+    self.assertEqual(f.lines, {})
+    self.assertEqual(f.stats, {})
+    self.assertEqual(f.local_path, None)
+    self.assertEqual(f.in_lcov, False)
+
+  def testUpdateCoverageEmpty(self):
+    """Test updating coverage when empty."""
+    f = self.cov_file
+    f.UpdateCoverage()
+    self.assertEqual(f.stats, {
+        'lines_executable': 0,
+        'lines_instrumented': 0,
+        'lines_covered': 0,
+        'files_executable': 1,
+    })
+
+  def testUpdateCoverageExeOnly(self):
+    """Test updating coverage when no lines are instrumented."""
+    f = self.cov_file
+    f.lines = {1: None, 2: None, 4: None}
+    f.UpdateCoverage()
+    self.assertEqual(f.stats, {
+        'lines_executable': 3,
+        'lines_instrumented': 0,
+        'lines_covered': 0,
+        'files_executable': 1,
+    })
+
+    # Now mark the file instrumented via in_lcov
+    f.in_lcov = True
+    f.UpdateCoverage()
+    self.assertEqual(f.stats, {
+        'lines_executable': 3,
+        'lines_instrumented': 0,
+        'lines_covered': 0,
+        'files_executable': 1,
+        'files_instrumented': 1,
+    })
+
+  def testUpdateCoverageExeAndInstr(self):
+    """Test updating coverage when no lines are covered."""
+    f = self.cov_file
+    f.lines = {1: None, 2: None, 4: 0, 5: 0, 7: None}
+    f.UpdateCoverage()
+    self.assertEqual(f.stats, {
+        'lines_executable': 5,
+        'lines_instrumented': 2,
+        'lines_covered': 0,
+        'files_executable': 1,
+        'files_instrumented': 1,
+    })
+
+  def testUpdateCoverageWhenCovered(self):
+    """Test updating coverage when lines are covered."""
+    f = self.cov_file
+    f.lines = {1: None, 2: None, 3: 1, 4: 0, 5: 0, 6: 1, 7: None}
+    f.UpdateCoverage()
+    self.assertEqual(f.stats, {
+        'lines_executable': 7,
+        'lines_instrumented': 4,
+        'lines_covered': 2,
+        'files_executable': 1,
+        'files_instrumented': 1,
+        'files_covered': 1,
+    })
+
+
+class TestCoveredDir(unittest.TestCase):
+  """Tests for croc.CoveredDir."""
+
+  def setUp(self):
+    self.cov_dir = croc.CoveredDir('/a/b/c')
+
+  def testInit(self):
+    """Test init."""
+    d = self.cov_dir
+
+    # Check initial values
+    self.assertEqual(d.dirpath, '/a/b/c')
+    self.assertEqual(d.files, {})
+    self.assertEqual(d.subdirs, {})
+    self.assertEqual(d.stats_by_group, {'all': {}})
+
+  def testGetTreeEmpty(self):
+    """Test getting empty tree."""
+    d = self.cov_dir
+    self.assertEqual(d.GetTree(), 'c/')
+
+  def testGetTreeStats(self):
+    """Test getting tree with stats."""
+    d = self.cov_dir
+    d.stats_by_group['all'] = croc.CoverageStats(
+        lines_executable=50, lines_instrumented=30, lines_covered=20)
+    d.stats_by_group['bar'] = croc.CoverageStats(
+        lines_executable=0, lines_instrumented=0, lines_covered=0)
+    d.stats_by_group['foo'] = croc.CoverageStats(
+        lines_executable=33, lines_instrumented=22, lines_covered=11)
+    # 'bar' group is skipped because it has no executable lines
+    self.assertEqual(
+        d.GetTree(),
+        'c/                               all:20/30/50   foo:11/22/33')
+
+  def testGetTreeSubdir(self):
+    """Test getting tree with subdirs."""
+    d1 = self.cov_dir = croc.CoveredDir('/a')
+    d2 = self.cov_dir = croc.CoveredDir('/a/b')
+    d3 = self.cov_dir = croc.CoveredDir('/a/c')
+    d4 = self.cov_dir = croc.CoveredDir('/a/b/d')
+    d5 = self.cov_dir = croc.CoveredDir('/a/b/e')
+    d1.subdirs = {'/a/b': d2, '/a/c': d3}
+    d2.subdirs = {'/a/b/d': d4, '/a/b/e': d5}
+    self.assertEqual(d1.GetTree(), 'a/\n  b/\n    d/\n    e/\n  c/')
+
+
+class TestCoverage(unittest.TestCase):
+  """Tests for croc.Coverage."""
+
+  def MockWalk(self, src_dir):
+    """Mock for os.walk().
+
+    Args:
+      src_dir: Source directory to walk.
+
+    Returns:
+      A list of (dirpath, dirnames, filenames) tuples.
+    """
+    self.mock_walk_calls.append(src_dir)
+    return self.mock_walk_return
+
+  def MockScanFile(self, filename, language):
+    """Mock for croc_scan.ScanFile().
+
+    Args:
+      filename: Path to file to scan.
+      language: Language for file.
+
+    Returns:
+      A list of executable lines.
+    """
+    self.mock_scan_calls.append([filename, language])
+    if filename in self.mock_scan_return:
+      return self.mock_scan_return[filename]
+    else:
+      return self.mock_scan_return['default']
+
+  def setUp(self):
+    """Per-test setup."""
+
+    # Empty coverage object
+    self.cov = croc.Coverage()
+
+    # Coverage object with minimal setup
+    self.cov_minimal = croc.Coverage()
+    self.cov_minimal.AddRoot('/src')
+    self.cov_minimal.AddRoot('c:\\source')
+    self.cov_minimal.AddRule('^_/', include=1, group='my')
+    self.cov_minimal.AddRule('.*\\.c$', language='C')
+    self.cov_minimal.AddRule('.*\\.c##$', language='C##')  # sharper than thou
+
+    # Data for MockWalk()
+    self.mock_walk_calls = []
+    self.mock_walk_return = []
+
+    # Data for MockScanFile()
+    self.mock_scan_calls = []
+    self.mock_scan_return = {'default': [1]}
+
+  def testInit(self):
+    """Test init."""
+    c = self.cov
+    self.assertEqual(c.files, {})
+    self.assertEqual(c.root_dirs, [])
+    self.assertEqual(c.print_stats, [])
+    self.assertEqual(c.rules, [])
+
+  def testAddRoot(self):
+    """Test AddRoot() and CleanupFilename()."""
+    c = self.cov
+
+    # Check for identity on already-clean filenames
+    self.assertEqual(c.CleanupFilename(''), '')
+    self.assertEqual(c.CleanupFilename('a'), 'a')
+    self.assertEqual(c.CleanupFilename('.a'), '.a')
+    self.assertEqual(c.CleanupFilename('..a'), '..a')
+    self.assertEqual(c.CleanupFilename('a.b'), 'a.b')
+    self.assertEqual(c.CleanupFilename('a/b/c'), 'a/b/c')
+    self.assertEqual(c.CleanupFilename('a/b/c/'), 'a/b/c/')
+
+    # Backslash to forward slash
+    self.assertEqual(c.CleanupFilename('a\\b\\c'), 'a/b/c')
+
+    # Handle relative paths
+    self.assertEqual(c.CleanupFilename('.'),
+                     c.CleanupFilename(os.path.abspath('.')))
+    self.assertEqual(c.CleanupFilename('..'),
+                     c.CleanupFilename(os.path.abspath('..')))
+    self.assertEqual(c.CleanupFilename('./foo/bar'),
+                     c.CleanupFilename(os.path.abspath('./foo/bar')))
+    self.assertEqual(c.CleanupFilename('../../a/b/c'),
+                     c.CleanupFilename(os.path.abspath('../../a/b/c')))
+
+    # Replace alt roots
+    c.AddRoot('foo')
+    self.assertEqual(c.CleanupFilename('foo'), '_')
+    self.assertEqual(c.CleanupFilename('foo/bar/baz'), '_/bar/baz')
+    self.assertEqual(c.CleanupFilename('aaa/foo'), 'aaa/foo')
+
+    # Alt root replacement is applied for all roots
+    c.AddRoot('foo/bar', '_B')
+    self.assertEqual(c.CleanupFilename('foo/bar/baz'), '_B/baz')
+
+    # Can use previously defined roots in cleanup
+    c.AddRoot('_/nom/nom/nom', '_CANHAS')
+    self.assertEqual(c.CleanupFilename('foo/nom/nom/nom/cheezburger'),
+                     '_CANHAS/cheezburger')
+
+    # Verify roots starting with UNC paths or drive letters work, and that
+    # more than one root can point to the same alt_name
+    c.AddRoot('/usr/local/foo', '_FOO')
+    c.AddRoot('D:\\my\\foo', '_FOO')
+    self.assertEqual(c.CleanupFilename('/usr/local/foo/a/b'), '_FOO/a/b')
+    self.assertEqual(c.CleanupFilename('D:\\my\\foo\\c\\d'), '_FOO/c/d')
+
+    # Cannot specify a blank alt_name
+    self.assertRaises(ValueError, c.AddRoot, 'some_dir', '')
+
+  def testAddRule(self):
+    """Test AddRule() and ClassifyFile()."""
+    c = self.cov
+
+    # With only the default rule, nothing gets kept
+    self.assertEqual(c.ClassifyFile('_/src/'), {})
+    self.assertEqual(c.ClassifyFile('_/src/a.c'), {})
+
+    # Add rules to include a tree and set a default group
+    c.AddRule('^_/src/', include=1, group='source')
+    self.assertEqual(c.ClassifyFile('_/src/'),
+                     {'include': 1, 'group': 'source'})
+    self.assertEqual(c.ClassifyFile('_/notsrc/'), {})
+    self.assertEqual(c.ClassifyFile('_/src/a.c'),
+                     {'include': 1, 'group': 'source'})
+
+    # Define some languages and groups
+    c.AddRule('.*\\.(c|h)$', language='C')
+    c.AddRule('.*\\.py$', language='Python')
+    c.AddRule('.*_test\\.', group='test')
+    self.assertEqual(c.ClassifyFile('_/src/a.c'),
+                     {'include': 1, 'group': 'source', 'language': 'C'})
+    self.assertEqual(c.ClassifyFile('_/src/a.h'),
+                     {'include': 1, 'group': 'source', 'language': 'C'})
+    self.assertEqual(c.ClassifyFile('_/src/a.cpp'),
+                     {'include': 1, 'group': 'source'})
+    self.assertEqual(c.ClassifyFile('_/src/a_test.c'),
+                     {'include': 1, 'group': 'test', 'language': 'C'})
+    self.assertEqual(c.ClassifyFile('_/src/test_a.c'),
+                     {'include': 1, 'group': 'source', 'language': 'C'})
+    self.assertEqual(c.ClassifyFile('_/src/foo/bar.py'),
+                     {'include': 1, 'group': 'source', 'language': 'Python'})
+    self.assertEqual(c.ClassifyFile('_/src/test.py'),
+                     {'include': 1, 'group': 'source', 'language': 'Python'})
+
+    # Exclude a path (for example, anything in a build output dir)
+    c.AddRule('.*/build/', include=0)
+    # But add back in a dir which matched the above rule but isn't a build
+    # output dir
+    c.AddRule('_/src/tools/build/', include=1)
+    self.assertEqual(c.ClassifyFile('_/src/build.c').get('include'), 1)
+    self.assertEqual(c.ClassifyFile('_/src/build/').get('include'), 0)
+    self.assertEqual(c.ClassifyFile('_/src/build/a.c').get('include'), 0)
+    self.assertEqual(c.ClassifyFile('_/src/tools/build/').get('include'), 1)
+    self.assertEqual(c.ClassifyFile('_/src/tools/build/t.c').get('include'), 1)
+
+  def testGetCoveredFile(self):
+    """Test GetCoveredFile()."""
+    c = self.cov_minimal
+
+    # Not currently any covered files
+    self.assertEqual(c.GetCoveredFile('_/a.c'), None)
+
+    # Add some files
+    a_c = c.GetCoveredFile('_/a.c', add=True)
+    b_c = c.GetCoveredFile('_/b.c##', add=True)
+    self.assertEqual(a_c.filename, '_/a.c')
+    self.assertEqual(a_c.attrs, {'include': 1, 'group': 'my', 'language': 'C'})
+    self.assertEqual(b_c.filename, '_/b.c##')
+    self.assertEqual(b_c.attrs,
+                     {'include': 1, 'group': 'my', 'language': 'C##'})
+
+    # Specifying the same filename should return the existing object
+    self.assertEqual(c.GetCoveredFile('_/a.c'), a_c)
+    self.assertEqual(c.GetCoveredFile('_/a.c', add=True), a_c)
+
+    # Filenames get cleaned on the way in, as do root paths
+    self.assertEqual(c.GetCoveredFile('/src/a.c'), a_c)
+    self.assertEqual(c.GetCoveredFile('c:\\source\\a.c'), a_c)
+
+    # TODO: Make sure that covered files require language, group, and include
+    # (since that checking is now done in GetCoveredFile() rather than
+    # ClassifyFile())
+
+  def testRemoveCoveredFile(self):
+    """Test RemoveCoveredFile()."""
+    # TODO: TEST ME!
+
+  def testParseLcov(self):
+    """Test ParseLcovData()."""
+    c = self.cov_minimal
+
+    c.ParseLcovData([
+        '# Ignore unknown lines',
+        # File we should include'
+        'SF:/src/a.c',
+        'DA:10,1',
+        'DA:11,0',
+        'DA:12,1   \n',  # Trailing whitespace should get stripped
+        'end_of_record',
+        # File we should ignore
+        'SF:/not_src/a.c',
+        'DA:20,1',
+        'end_of_record',
+        # Same as first source file, but alternate root
+        'SF:c:\\source\\a.c',
+        'DA:30,1',
+        'end_of_record',
+        # Ignore extra end of record
+        'end_of_record',
+        # Ignore data points after end of record
+        'DA:40,1',
+        # Instrumented but uncovered file
+        'SF:/src/b.c',
+        'DA:50,0',
+        'end_of_record',
+        # Empty file (instrumented but no executable lines)
+        'SF:c:\\source\\c.c',
+        'end_of_record',
+    ])
+
+    # We should know about three files
+    self.assertEqual(sorted(c.files), ['_/a.c', '_/b.c', '_/c.c'])
+
+    # Check expected contents
+    a_c = c.GetCoveredFile('_/a.c')
+    self.assertEqual(a_c.lines, {10: 1, 11: 0, 12: 1, 30: 1})
+    self.assertEqual(a_c.stats, {
+        'files_executable': 1,
+        'files_instrumented': 1,
+        'files_covered': 1,
+        'lines_instrumented': 4,
+        'lines_executable': 4,
+        'lines_covered': 3,
+    })
+    self.assertEqual(a_c.in_lcov, True)
+
+    b_c = c.GetCoveredFile('_/b.c')
+    self.assertEqual(b_c.lines, {50: 0})
+    self.assertEqual(b_c.stats, {
+        'files_executable': 1,
+        'files_instrumented': 1,
+        'lines_instrumented': 1,
+        'lines_executable': 1,
+        'lines_covered': 0,
+    })
+    self.assertEqual(b_c.in_lcov, True)
+
+    c_c = c.GetCoveredFile('_/c.c')
+    self.assertEqual(c_c.lines, {})
+    self.assertEqual(c_c.stats, {
+        'files_executable': 1,
+        'files_instrumented': 1,
+        'lines_instrumented': 0,
+        'lines_executable': 0,
+        'lines_covered': 0,
+    })
+    self.assertEqual(c_c.in_lcov, True)
+
+    # TODO: Test that files are marked as instrumented if they come from lcov,
+    # even if they don't have any instrumented lines.  (and that in_lcov is set
+    # for those files - probably should set that via some method rather than
+    # directly...)
+
+  def testGetStat(self):
+    """Test GetStat() and PrintStat()."""
+    c = self.cov
+
+    # Add some stats, so there's something to report
+    c.tree.stats_by_group = {
+        'all': {
+            'count_a': 10,
+            'count_b': 4,
+            'foo': 'bar',
+        },
+        'tests': {
+            'count_a': 2,
+            'count_b': 5,
+            'baz': 'bob',
+        },
+    }
+
+    # Test missing stats and groups
+    self.assertRaises(croc.CrocStatError, c.GetStat, 'nosuch')
+    self.assertRaises(croc.CrocStatError, c.GetStat, 'baz')
+    self.assertRaises(croc.CrocStatError, c.GetStat, 'foo', group='tests')
+    self.assertRaises(croc.CrocStatError, c.GetStat, 'foo', group='nosuch')
+
+    # Test returning defaults
+    self.assertEqual(c.GetStat('nosuch', default=13), 13)
+    self.assertEqual(c.GetStat('baz', default='aaa'), 'aaa')
+    self.assertEqual(c.GetStat('foo', group='tests', default=0), 0)
+    self.assertEqual(c.GetStat('foo', group='nosuch', default=''), '')
+
+    # Test getting stats
+    self.assertEqual(c.GetStat('count_a'), 10)
+    self.assertEqual(c.GetStat('count_a', group='tests'), 2)
+    self.assertEqual(c.GetStat('foo', default='baz'), 'bar')
+
+    # Test stat math (eval)
+    self.assertEqual(c.GetStat('count_a - count_b'), 6)
+    self.assertEqual(c.GetStat('100.0 * count_a / count_b', group='tests'),
+                     40.0)
+    # Should catch eval errors
+    self.assertRaises(croc.CrocStatError, c.GetStat, '100 / 0')
+    self.assertRaises(croc.CrocStatError, c.GetStat, 'count_a -')
+
+    # Test nested stats via S()
+    self.assertEqual(c.GetStat('count_a - S("count_a", group="tests")'), 8)
+    self.assertRaises(croc.CrocStatError, c.GetStat, 'S()')
+    self.assertRaises(croc.CrocStatError, c.GetStat, 'S("nosuch")')
+
+    # Test PrintStat()
+    # We won't see the first print, but at least verify it doesn't assert
+    c.PrintStat('count_a', format='(test to stdout: %s)')
+    # Send subsequent prints to a file
+    f = StringIO.StringIO()
+    c.PrintStat('count_b', outfile=f)
+    # Test specifying output format
+    c.PrintStat('count_a', format='Count A = %05d', outfile=f)
+    # Test specifing additional keyword args
+    c.PrintStat('count_a', group='tests', outfile=f)
+    c.PrintStat('nosuch', default=42, outfile=f)
+    self.assertEqual(f.getvalue(), ("""\
+GetStat('count_b') = 4
+Count A = 00010
+GetStat('count_a') = 2
+GetStat('nosuch') = 42
+"""))
+    f.close()
+
+  def testAddConfigEmpty(self):
+    """Test AddConfig() with empty config."""
+    c = self.cov
+    # Most minimal config is an empty dict; should do nothing
+    c.AddConfig('{} # And we ignore comments')
+
+  def testAddConfig(self):
+    """Test AddConfig()."""
+    c = self.cov
+    lcov_queue = []
+    addfiles_queue = []
+
+    c.AddConfig("""{
+        'roots' : [
+          {'root' : '/foo'},
+          {'root' : '/bar', 'altname' : 'BAR'},
+        ],
+        'rules' : [
+          {'regexp' : '^_/', 'group' : 'apple'},
+          {'regexp' : 're2', 'include' : 1, 'language' : 'elvish'},
+        ],
+        'lcov_files' : ['a.lcov', 'b.lcov'],
+        'add_files' : ['/src', 'BAR/doo'],
+        'print_stats' : [
+          {'stat' : 'count_a'},
+          {'stat' : 'count_b', 'group' : 'tests'},
+        ],
+        'extra_key' : 'is ignored',
+    }""", lcov_queue=lcov_queue, addfiles_queue=addfiles_queue)
+
+    self.assertEqual(lcov_queue, ['a.lcov', 'b.lcov'])
+    self.assertEqual(addfiles_queue, ['/src', 'BAR/doo'])
+    self.assertEqual(c.root_dirs, [['/foo', '_'], ['/bar', 'BAR']])
+    self.assertEqual(c.print_stats, [
+        {'stat': 'count_a'},
+        {'stat': 'count_b', 'group': 'tests'},
+    ])
+    # Convert compiled re's back to patterns for comparison
+    rules = [[r[0].pattern] + r[1:] for r in c.rules]
+    self.assertEqual(rules, [
+        ['^_/', {'group': 'apple'}],
+        ['re2', {'include': 1, 'language': 'elvish'}],
+    ])
+
+  def testAddFilesSimple(self):
+    """Test AddFiles() simple call."""
+    c = self.cov_minimal
+    c.add_files_walk = self.MockWalk
+    c.scan_file = self.MockScanFile
+
+    c.AddFiles('/a/b/c')
+    self.assertEqual(self.mock_walk_calls, ['/a/b/c'])
+    self.assertEqual(self.mock_scan_calls, [])
+    self.assertEqual(c.files, {})
+
+  def testAddFilesRootMap(self):
+    """Test AddFiles() with root mappings."""
+    c = self.cov_minimal
+    c.add_files_walk = self.MockWalk
+    c.scan_file = self.MockScanFile
+
+    c.AddRoot('_/subdir', 'SUBDIR')
+
+    # AddFiles() should replace the 'SUBDIR' alt_name, then match both
+    # possible roots for the '_' alt_name.
+    c.AddFiles('SUBDIR/foo')
+    self.assertEqual(self.mock_walk_calls,
+                     ['/src/subdir/foo', 'c:/source/subdir/foo'])
+    self.assertEqual(self.mock_scan_calls, [])
+    self.assertEqual(c.files, {})
+
+  def testAddFilesNonEmpty(self):
+    """Test AddFiles() where files are returned."""
+
+    c = self.cov_minimal
+    c.add_files_walk = self.MockWalk
+    c.scan_file = self.MockScanFile
+
+    # Add a rule to exclude a subdir
+    c.AddRule('^_/proj1/excluded/', include=0)
+
+    # Add a rule to exclude adding some fiels
+    c.AddRule('.*noscan.c$', add_if_missing=0)
+
+    # Set data for mock walk and scan
+    self.mock_walk_return = [
+        [
+            '/src/proj1',
+            ['excluded', 'subdir'],
+            ['a.c', 'no.f', 'yes.c', 'noexe.c', 'bob_noscan.c'],
+        ],
+        [
+            '/src/proj1/subdir',
+            [],
+            ['cherry.c'],
+        ],
+    ]
+
+    # Add a file with no executable lines; it should be scanned but not added
+    self.mock_scan_return['/src/proj1/noexe.c'] = []
+
+    c.AddFiles('/src/proj1')
+
+    self.assertEqual(self.mock_walk_calls, ['/src/proj1'])
+    self.assertEqual(self.mock_scan_calls, [
+        ['/src/proj1/a.c', 'C'],
+        ['/src/proj1/yes.c', 'C'],
+        ['/src/proj1/noexe.c', 'C'],
+        ['/src/proj1/subdir/cherry.c', 'C'],
+    ])
+
+    # Include files from the main dir and subdir
+    self.assertEqual(sorted(c.files), [
+        '_/proj1/a.c',
+        '_/proj1/subdir/cherry.c',
+        '_/proj1/yes.c'])
+
+    # Excluded dir should have been pruned from the mock walk data dirnames.
+    # In the real os.walk() call this prunes the walk.
+    self.assertEqual(self.mock_walk_return[0][1], ['subdir'])
+
+
+  def testEmptyTreeStats(self):
+    """Make sure we don't choke when absolutely nothing happened.
+
+    How we might hit this: bot compile error."""
+    c = self.cov_minimal
+    t = c.tree
+    t.stats_by_group['all'].AddDefaults()
+    self.assertEqual(t.stats_by_group, {
+        'all': { 'files_covered': 0,
+                 'files_instrumented': 0,
+                 'files_executable': 0,
+                 'lines_covered': 0,
+                 'lines_instrumented': 0,
+                 'lines_executable': 0 }})
+
+  def testUpdateTreeStats(self):
+    """Test UpdateTreeStats()."""
+
+    c = self.cov_minimal
+    c.AddRule('.*_test', group='test')
+
+    # Fill the files list
+    c.ParseLcovData([
+        'SF:/src/a.c',
+        'DA:10,1', 'DA:11,1', 'DA:20,0',
+        'end_of_record',
+        'SF:/src/a_test.c',
+        'DA:10,1', 'DA:11,1', 'DA:12,1',
+        'end_of_record',
+        'SF:/src/foo/b.c',
+        'DA:10,1', 'DA:11,1', 'DA:20,0', 'DA:21,0', 'DA:30,0',
+        'end_of_record',
+        'SF:/src/foo/b_test.c',
+        'DA:20,0', 'DA:21,0', 'DA:22,0',
+        'end_of_record',
+    ])
+    c.UpdateTreeStats()
+
+    t = c.tree
+    self.assertEqual(t.dirpath, '')
+    self.assertEqual(sorted(t.files), [])
+    self.assertEqual(sorted(t.subdirs), ['_'])
+    self.assertEqual(t.stats_by_group, {
+        'all': {
+            'files_covered': 3,
+            'files_executable': 4,
+            'lines_executable': 14,
+            'lines_covered': 7,
+            'lines_instrumented': 14,
+            'files_instrumented': 4,
+        },
+        'my': {
+            'files_covered': 2,
+            'files_executable': 2,
+            'lines_executable': 8,
+            'lines_covered': 4,
+            'lines_instrumented': 8,
+            'files_instrumented': 2,
+        },
+        'test': {
+            'files_covered': 1,
+            'files_executable': 2,
+            'lines_executable': 6,
+            'lines_covered': 3,
+            'lines_instrumented': 6,
+            'files_instrumented': 2,
+        },
+    })
+
+    t = t.subdirs['_']
+    self.assertEqual(t.dirpath, '_')
+    self.assertEqual(sorted(t.files), ['a.c', 'a_test.c'])
+    self.assertEqual(sorted(t.subdirs), ['foo'])
+    self.assertEqual(t.stats_by_group, {
+        'all': {
+            'files_covered': 3,
+            'files_executable': 4,
+            'lines_executable': 14,
+            'lines_covered': 7,
+            'lines_instrumented': 14,
+            'files_instrumented': 4,
+        },
+        'my': {
+            'files_covered': 2,
+            'files_executable': 2,
+            'lines_executable': 8,
+            'lines_covered': 4,
+            'lines_instrumented': 8,
+            'files_instrumented': 2,
+        },
+        'test': {
+            'files_covered': 1,
+            'files_executable': 2,
+            'lines_executable': 6,
+            'lines_covered': 3,
+            'lines_instrumented': 6,
+            'files_instrumented': 2,
+        },
+    })
+
+    t = t.subdirs['foo']
+    self.assertEqual(t.dirpath, '_/foo')
+    self.assertEqual(sorted(t.files), ['b.c', 'b_test.c'])
+    self.assertEqual(sorted(t.subdirs), [])
+    self.assertEqual(t.stats_by_group, {
+        'test': {
+            'files_executable': 1,
+            'files_instrumented': 1,
+            'lines_executable': 3,
+            'lines_instrumented': 3,
+            'lines_covered': 0,
+        },
+        'all': {
+            'files_covered': 1,
+            'files_executable': 2,
+            'lines_executable': 8,
+            'lines_covered': 2,
+            'lines_instrumented': 8,
+            'files_instrumented': 2,
+        },
+        'my': {
+            'files_covered': 1,
+            'files_executable': 1,
+            'lines_executable': 5,
+            'lines_covered': 2,
+            'lines_instrumented': 5,
+            'files_instrumented': 1,
+        }
+    })
+
+  # TODO: test: less important, since these are thin wrappers around other
+  # tested methods.
+  #     ParseConfig()
+  #     ParseLcovFile()
+  #     PrintTree()
+
+
+if __name__ == '__main__':
+  unittest.main()