Added coverage script and tests.

build/android/emma_coverage_stats.py

Index: build/android/emma_coverage_stats.py
diff --git a/build/android/emma_coverage_stats.py b/build/android/emma_coverage_stats.py
new file mode 100755
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+++ b/build/android/emma_coverage_stats.py
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+#!/usr/bin/python
+# Copyright 2015 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.
+
+"""Generates incremental code coverage reports for Java code in Chromium."""
+
+import collections
+import os
+from xml.etree import ElementTree
+
+NOT_EXECUTABLE = -1
+NOT_COVERED = 0
+COVERED = 1
+PARTIALLY_COVERED = 2
+
+# Coverage information about a single line of code.
+LineCoverage = collections.namedtuple(
+    'LineCoverage',
+    ['lineno', 'source', 'covered_status', 'fractional_line_coverage'])
+
+
+class _EmmaHtmlParser(object):
+  """Encapsulates HTML file parsing operations.
+
+  This class contains all operations related to parsing HTML files that were
+  produced using the EMMA code coverage tool.
+
+  Example HTML:
+
+  Package links:
+    <a href="_files/1.html">org.chromium.chrome</a>
+    This is returned by the selector |XPATH_SELECT_PACKAGE_ELEMENTS|.
+
+  Class links:
+    <a href="1e.html">DoActivity.java</a>
+    This is returned by the selector |XPATH_SELECT_CLASS_ELEMENTS|.
+
+  Line coverage data:
+    <tr class="p">
+       <td class="l" title="78% line coverage (7 out of 9)">108</td>
+       <td title="78% line coverage (7 out of 9 instructions)">
+         if (index < 0 || index = mSelectors.size()) index = 0;</td>
+    </tr>
+    <tr>
+       <td class="l">109</td>
+       <td> </td>
+    </tr>
+    <tr class="c">
+       <td class="l">110</td>
+       <td>        if (mSelectors.get(index) != null) {</td>
+    </tr>
+    <tr class="z">
+       <td class="l">111</td>
+       <td>            for (int i = 0; i < mSelectors.size(); i++) {</td>
+    </tr>
+    Each <tr> element is returned by the selector |XPATH_SELECT_LOC|.
+
+    We can parse this to get:
+      1. Line number
+      2. Line of source code
+      3. Coverage status (c, z, or p)
+      4. Fractional coverage value (% out of 100 if PARTIALLY_COVERED)
+  """
+  # Selector to match all <a> elements within the rows that are in the table
+  # that displays all of the different packages.
+  _XPATH_SELECT_PACKAGE_ELEMENTS = './/BODY/TABLE[4]/TR/TD/A'
+
+  # Selector to match all <a> elements within the rows that are in the table
+  # that displays all of the different packages within a class.
+  _XPATH_SELECT_CLASS_ELEMENTS = './/BODY/TABLE[3]/TR/TD/A'
+
+  # Selector to match all <tr> elements within the table containing Java source
+  # code in an EMMA HTML file.
+  _XPATH_SELECT_LOC = './/BODY/TABLE[4]/TR'
+
+  # Children of HTML elements are represented as a list in ElementTree. These
+  # constants represent list indices corresponding to relevant child elements.
+
+  # Child 1 contains percentage covered for a line.
+  _ELEMENT_PERCENT_COVERED = 1
+
+  # Child 1 contains the original line of source code.
+  _ELEMENT_CONTAINING_SOURCE_CODE = 1
+
+  # Child 0 contains the line number.
+  _ELEMENT_CONTAINING_LINENO = 0
+
+  # Maps CSS class names to corresponding coverage constants.
+  _CSS_TO_STATUS = {'c': COVERED, 'p': PARTIALLY_COVERED, 'z': NOT_COVERED}
+
+  # UTF-8 no break space.
+  _NO_BREAK_SPACE = '\xc2\xa0'
+
+  def __init__(self, emma_file_base_dir):
+    """Initializes _EmmaHtmlParser.
+
+    Args:
+      emma_file_base_dir: Path to the location where EMMA report files are
+        stored. Should be where index.html is stored.
+    """
+    self._base_dir = emma_file_base_dir
+    self._emma_files_path = os.path.join(self._base_dir, '_files')
+    self._index_path = os.path.join(self._base_dir, 'index.html')
+
+  def GetLineCoverage(self, emma_file_path):
+    """Returns a list of LineCoverage objects for the given EMMA HTML file.
+
+    Args:
+      emma_file_path: String representing the path to the EMMA HTML file.
+
+    Returns:
+      A list of LineCoverage objects.
+    """
+    line_tr_elements = self._FindElements(
+        emma_file_path, self._XPATH_SELECT_LOC)
+    line_coverage = []
+    for tr in line_tr_elements:
+      # Get the coverage status.
+      coverage_status = self._CSS_TO_STATUS.get(tr.get('CLASS'), NOT_EXECUTABLE)
+      # Get the fractional coverage value.
+      if coverage_status == PARTIALLY_COVERED:
+        title_attribute = (tr[self._ELEMENT_PERCENT_COVERED].get('TITLE'))
+        # Parse string that contains percent covered: "83% line coverage ...".
+        percent_covered = title_attribute.split('%')[0]
+        fractional_coverage = int(percent_covered) / 100.0
+      else:
+        fractional_coverage = 1.0
+
+      # Get the line number.
+      lineno_element = tr[self._ELEMENT_CONTAINING_LINENO]
+      # Handles oddly formatted HTML (where there is an extra <a> tag).
+      lineno = int(lineno_element.text or
+                   lineno_element[self._ELEMENT_CONTAINING_LINENO].text)
+      # Get the original line of Java source code.
+      raw_source = tr[self._ELEMENT_CONTAINING_SOURCE_CODE].text
+      utf8_source = raw_source.encode('UTF-8')
+      source = utf8_source.replace(self._NO_BREAK_SPACE, ' ')
+
+      line = LineCoverage(lineno, source, coverage_status, fractional_coverage)
+      line_coverage.append(line)
+
+    return line_coverage
+
+  def GetPackageNameToEmmaFileDict(self):
+    """Returns a dict mapping Java packages to EMMA HTML coverage files.
+
+    Parses the EMMA index.html file to get a list of packages, then parses each
+    package HTML file to get a list of classes for that package, and creates
+    a dict with this info.
+
+    Returns:
+      A dict mapping string representation of Java packages (with class
+        names appended) to the corresponding file paths of EMMA HTML files.
+    """
+    # These <a> elements contain each package name and the path of the file
+    # where all classes within said package are listed.
+    package_link_elements = self._FindElements(
+        self._index_path, self._XPATH_SELECT_PACKAGE_ELEMENTS)
+    # Maps file path of package directory (EMMA generated) to package name.
+    # Ex. emma_dir/f.html: org.chromium.chrome.
+    package_links = {
+      os.path.join(self._base_dir, link.attrib['HREF']): link.text
+      for link in package_link_elements if 'HREF' in link.attrib
+    }
+
+    package_to_emma = {}
+    for package_emma_file_path, package_name in package_links.iteritems():
+      # These <a> elements contain each class name in the current package and
+      # the path of the file where the coverage info is stored for each class.
+      coverage_file_link_elements = self._FindElements(
+          package_emma_file_path, self._XPATH_SELECT_CLASS_ELEMENTS)
+
+      for coverage_file_element in coverage_file_link_elements:
+        emma_coverage_file_path = os.path.join(
+            self._emma_files_path, coverage_file_element.attrib['HREF'])
+        full_package_name = '%s.%s' % (package_name, coverage_file_element.text)
+        package_to_emma[full_package_name] = emma_coverage_file_path
+
+    return package_to_emma
+
+  def _FindElements(self, file_path, xpath_selector):
+    """Reads a HTML file and performs an XPath match.
+
+    Args:
+      file_path: String representing the path to the HTML file.
+      xpath_selector: String representing xpath search pattern.
+
+    Returns:
+      A list of ElementTree.Elements matching the given XPath selector.
+        Returns an empty list if there is no match.
+    """
+    with open(file_path) as f:
+      file_contents = f.read().decode('ISO-8859-1').encode('UTF-8')
+      root = ElementTree.fromstring(file_contents)
+      return root.findall(xpath_selector)