Add coverage

tools/telemetry/third_party/coverage/tests/helpers.py

+# Licensed under the Apache License: http://www.apache.org/licenses/LICENSE-2.0
+# For details: https://bitbucket.org/ned/coveragepy/src/default/NOTICE.txt
+
+"""Helpers for coverage.py tests."""
+
+import subprocess
+
+
+def run_command(cmd):
+    """Run a command in a sub-process.
+
+    Returns the exit status code and the combined stdout and stderr.
+
+    """
+    proc = subprocess.Popen(
+        cmd, shell=True,
+        stdin=subprocess.PIPE, stdout=subprocess.PIPE,
+        stderr=subprocess.STDOUT
+        )
+    output, _ = proc.communicate()
+    status = proc.returncode
+
+    # Get the output, and canonicalize it to strings with newlines.
+    if not isinstance(output, str):
+        output = output.decode('utf-8')
+    output = output.replace('\r', '')
+
+    return status, output
+
+
+class CheckUniqueFilenames(object):
+    """Asserts the uniqueness of file names passed to a function."""
+    def __init__(self, wrapped):
+        self.filenames = set()
+        self.wrapped = wrapped
+
+    @classmethod
+    def hook(cls, cov, method_name):
+        """Replace a method with our checking wrapper."""
+        method = getattr(cov, method_name)
+        hook = cls(method)
+        setattr(cov, method_name, hook.wrapper)
+        return hook
+
+    def wrapper(self, filename, *args, **kwargs):
+        """The replacement method.  Check that we don't have dupes."""
+        assert filename not in self.filenames, (
+            "File name %r passed to %r twice" % (filename, self.wrapped)
+            )
+        self.filenames.add(filename)
+        ret = self.wrapped(filename, *args, **kwargs)
+        return ret