Updated script to capture useful coverage stats.

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
index dc60d31b8d1ef45b88bff84d92c871505097bc7f..8500890703498679c76431b0ced124cd2101bc84 100755
--- a/build/android/emma_coverage_stats.py
+++ b/build/android/emma_coverage_stats.py
@@ -3,12 +3,29 @@
 # 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."""
+"""Generates incremental code coverage reports for Java code in Chromium.
 
+Usage:
+
+  build/android/coverage.py -v --out <output file path> --emma-dir
+    <EMMA file directory> --lines-for-coverage-file
+    <path to file containing lines for coverage>
+
+  Creates a JSON representation of the overall and file coverage stats and saves
+  this information to the specified output file.
+"""
+
+import argparse
 import collections
+import json
+import logging
 import os
+import re
+import sys
 from xml.etree import ElementTree
 
+from pylib.utils import run_tests_helper
+
 NOT_EXECUTABLE = -1
 NOT_COVERED = 0
 COVERED = 1
@@ -67,7 +84,7 @@ class _EmmaHtmlParser(object):
   _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.
+  # that displays all of the different classes within a package.
   _XPATH_SELECT_CLASS_ELEMENTS = './/BODY/TABLE[3]/TR/TD/A'
 
   # Selector to match all <tr> elements within the table containing Java source
@@ -158,7 +175,7 @@ class _EmmaHtmlParser(object):
     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.
+    # Example: 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
@@ -171,10 +188,10 @@ class _EmmaHtmlParser(object):
       coverage_file_link_elements = self._FindElements(
           package_emma_file_path, self._XPATH_SELECT_CLASS_ELEMENTS)
 
-      for coverage_file_element in coverage_file_link_elements:
+      for class_name_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)
+            self._emma_files_path, class_name_element.attrib['HREF'])
+        full_package_name = '%s.%s' % (package_name, class_name_element.text)
         package_to_emma[full_package_name] = emma_coverage_file_path
 
     return package_to_emma
@@ -194,3 +211,274 @@ class _EmmaHtmlParser(object):
       file_contents = f.read().decode('ISO-8859-1').encode('UTF-8')
       root = ElementTree.fromstring(file_contents)
       return root.findall(xpath_selector)
+
+
+class _EmmaCoverageStats(object):
+  """Computes code coverage stats for Java code using the coverage tool EMMA.
+
+  This class provides an API that allows users to capture absolute code coverage
+  and code coverage on a subset of lines for each Java source file. Coverage
+  reports are generated in JSON format.
+  """
+  # Regular expression to get package name from Java package statement.
+  RE_PACKAGE_MATCH_GROUP = 'package'
+  RE_PACKAGE = re.compile(r'package (?P<%s>[\w.]*);' % RE_PACKAGE_MATCH_GROUP)
+
+  def __init__(self, emma_file_base_dir, files_for_coverage):
+    """Initialize _EmmaCoverageStats.
+
+    Args:
+      emma_file_base_dir: String representing the path to the base directory
+        where EMMA HTML coverage files are stored, i.e. parent of index.html.
+      files_for_coverage: A list of Java source code file paths to get EMMA
+        coverage for.
+    """
+    self._emma_parser = _EmmaHtmlParser(emma_file_base_dir)
+    self._source_to_emma = self._GetSourceFileToEmmaFileDict(files_for_coverage)
+
+  def GetCoverageDict(self, lines_for_coverage):
+    """Returns a dict containing detailed coverage information.
+
+    Gets detailed coverage stats for each file specified in the
+    |lines_for_coverage| dict and the total incremental number of lines covered
+    and executable for all files in |lines_for_coverage|.
+
+    Args:
+      lines_for_coverage: A dict mapping Java source file paths to lists of line
+        numbers.
+
+    Returns:
+      A dict containing coverage stats for the given dict of files and lines.
+        Contains absolute coverage stats for each file, coverage stats for each
+        file's lines specified in |lines_for_coverage|, line by line coverage
+        for each file, and overall coverage stats for the lines specified in
+        |lines_for_coverage|.
+    """
+    file_coverage = {}
+    for file_path, line_numbers in lines_for_coverage.iteritems():
+      file_coverage[file_path] = self.GetCoverageDictForFile(
+          file_path, line_numbers)
+
+    covered_statuses = [s['incremental'] for s in file_coverage.itervalues()]
+    num_covered_lines = sum(s['covered'] for s in covered_statuses)
+    num_total_lines = sum(s['total'] for s in covered_statuses)
+    return {
+      'files': file_coverage,
+      'patch': {
+        'incremental': {
+          'covered': num_covered_lines,
+          'total': num_total_lines
+        }
+      }
+    }
+
+  def GetCoverageDictForFile(self, file_path, line_numbers):
+    """Returns a dict containing detailed coverage info for the given file.
+
+    Args:
+      file_path: The path to the Java source file that we want to create the
+        coverage dict for.
+      line_numbers: A list of integer line numbers to retrieve additional stats
+        for.
+
+    Returns:
+      A dict containing absolute, incremental, and line by line coverage for
+        a file.
+    """
+    total_line_coverage = self._GetLineCoverageForFile(file_path)
+    incremental_line_coverage = [line for line in total_line_coverage
+                                 if line.lineno in line_numbers]
+    line_by_line_coverage = [
+      {
+        'line': line.source,
+        'coverage': line.covered_status,
+        'changed': line.lineno in line_numbers,
+      }
+      for line in total_line_coverage
+    ]
+    total_covered_lines, total_lines = (
+        self.GetSummaryStatsForLines(total_line_coverage))
+    incremental_covered_lines, incremental_total_lines = (
+        self.GetSummaryStatsForLines(incremental_line_coverage))
+
+    file_coverage_stats = {
+      'absolute': {
+        'covered': total_covered_lines,
+        'total': total_lines
+      },
+      'incremental': {
+        'covered': incremental_covered_lines,
+        'total': incremental_total_lines
+      },
+      'source': line_by_line_coverage,
+    }
+    return file_coverage_stats
+
+  def GetSummaryStatsForLines(self, line_coverage):
+    """Gets summary stats for a given list of LineCoverage objects.
+
+    Args:
+      line_coverage: A list of LineCoverage objects.
+
+    Returns:
+      A tuple containing the number of lines that are covered and the total
+        number of lines that are executable, respectively
+    """
+    partially_covered_sum = 0
+    covered_status_totals = {COVERED: 0, NOT_COVERED: 0, PARTIALLY_COVERED: 0}
+    for line in line_coverage:
+      status = line.covered_status
+      if status == NOT_EXECUTABLE:
+        continue
+      covered_status_totals[status] += 1
+      if status == PARTIALLY_COVERED:
+        partially_covered_sum += line.fractional_line_coverage
+
+    total_covered = covered_status_totals[COVERED] + partially_covered_sum
+    total_lines = sum(covered_status_totals.values())
+    return total_covered, total_lines
+
+  def _GetLineCoverageForFile(self, file_path):
+    """Gets a list of LineCoverage objects corresponding to the given file path.
+
+    Args:
+      file_path: String representing the path to the Java source file.
+
+    Returns:
+      A list of LineCoverage objects, or None if there is no EMMA file
+        for the given Java source file.
+    """
+    if file_path in self._source_to_emma:
+      emma_file = self._source_to_emma[file_path]
+      return self._emma_parser.GetLineCoverage(emma_file)
+    else:
+      logging.warning(
+          'No code coverage data for %s, skipping.', file_path)
+      return None
+
+  def _GetSourceFileToEmmaFileDict(self, files):
+    """Gets a dict used to correlate Java source files with EMMA HTML files.
+
+    This method gathers the information needed to correlate EMMA HTML
+    files with Java source files. EMMA XML and plain text reports do not provide
+    line by line coverage data, so HTML reports must be used instead.
+    Unfortunately, the HTML files that are created are given garbage names
+    (i.e 1.html) so we need to manually correlate EMMA HTML files
+    with the original Java source files.
+
+    Args:
+      files: A list of file names for which coverage information is desired.
+
+    Returns:
+      A dict mapping Java source file paths to EMMA HTML file paths.
+    """
+    # Maps Java source file paths to package names.
+    # Example: /usr/code/file.java -> org.chromium.file.java.
+    source_to_package = {}
+    for file_path in files:
+      package = self.GetPackageNameFromFile(file_path)
+      if package:
+        source_to_package[file_path] = package
+      else:
+        logging.warning("Skipping %s because it doesn\'t have a package "
+                        "statement.", file_path)
+
+    # Maps package names to EMMA report HTML files.
+    # Example: org.chromium.file.java -> out/coverage/1a.html.
+    package_to_emma = self._emma_parser.GetPackageNameToEmmaFileDict()
+    # Finally, we have a dict mapping Java file paths to EMMA report files.
+    # Example: /usr/code/file.java -> out/coverage/1a.html.
+    source_to_emma = {source: package_to_emma.get(package)
+                      for source, package in source_to_package.iteritems()}
+    return source_to_emma
+
+  @staticmethod
+  def NeedsCoverage(file_path):
+    """Checks to see if the file needs to be analyzed for code coverage.
+
+    Args:
+      file_path: A string representing path to the file.
+
+    Returns:
+      True for Java files that exist, False for all others.
+    """
+    if os.path.splitext(file_path)[1] == '.java' and os.path.exists(file_path):
+      return True
+    else:
+      logging.debug(
+          'Skipping file %s, cannot compute code coverage.', file_path)
+      return False
+
+  @staticmethod
+  def GetPackageNameFromFile(file_path):
+    """Gets the full package name including the file name for a given file path.
+
+    Args:
+      file_path: String representing the path to the Java source file.
+
+    Returns:
+      A string representing the full package name with file name appended or
+        None if there is no package statement in the file.
+    """
+    with open(file_path) as f:
+      file_content = f.read()
+      package_match = re.search(_EmmaCoverageStats.RE_PACKAGE, file_content)
+      if package_match:
+        package = package_match.group(_EmmaCoverageStats.RE_PACKAGE_MATCH_GROUP)
+        file_name = os.path.basename(file_path)
+        return '%s.%s' % (package, file_name)
+      else:
+        return None
+
+
+def GenerateCoverageReport(line_coverage_file, out_file_path, coverage_dir):
+  """Generates a coverage report for a given set of lines.
+
+  Writes the results of the coverage analysis to the file specified by
+  |out_file_path|.
+
+  Args:
+    line_coverage_file: The path to a file which contains a dict mapping file
+      names to lists of line numbers. Example: {file1: [1, 2, 3], ...} means
+      that we should compute coverage information on lines 1 - 3 for file1.
+    out_file_path: A string representing the location to write the JSON report.
+    coverage_dir: A string representing the file path where the EMMA
+      HTML coverage files are located (i.e. folder where index.html is located).
+  """
+  with open(line_coverage_file) as f:
+    potential_files_for_coverage = json.load(f)
+  files_for_coverage = {f: lines
+                        for f, lines in potential_files_for_coverage.iteritems()
+                        if _EmmaCoverageStats.NeedsCoverage(f)}
+  if not files_for_coverage:
+    logging.info('No Java files requiring coverage were included in %s.',
+                 line_coverage_file)
+    return
+
+  code_coverage = _EmmaCoverageStats(coverage_dir, files_for_coverage.keys())
+  coverage_results = code_coverage.GetCoverageDict(
+      files_for_coverage)
+
+  with open(out_file_path, 'w+') as out_status_file:
+    json.dump(coverage_results, out_status_file)
+
+
+def main():
+  argparser = argparse.ArgumentParser()
+  argparser.add_argument('--out', required=True, type=str,
+                         help='Report output file path.')
+  argparser.add_argument('--emma-dir', required=True, type=str,
+                         help='EMMA HTML report directory.')
+  argparser.add_argument('--lines-for-coverage-file', required=True, type=str,
+                         help='File containing a JSON object. Should contain a '
+                         'dict mapping file names to lists of line numbers of '
+                         'code for which coverage information is desired.')
+  argparser.add_argument('-v', '--verbose', action='count',
+                         help='Print verbose log information.')
+  args = argparser.parse_args()
+  run_tests_helper.SetLogLevel(args.verbose)
+  GenerateCoverageReport(args.lines_for_coverage_file, args.out, args.emma_dir)
+
+
+if __name__ == '__main__':
+  sys.exit(main())